Lisa Ernoul

Angela Wardell-Johnson

Loïc Willm

Arnaud Béchet

Olivier Boutron

Raphaël Mathevet

Stephan Arnassant

Alain Sandoz

Participatory mapping: Exploring landscape values associated with an iconic species

Participatory mapping provides a way to collate a wide range of landscape values providing a visual representation to inform conservation planning. We tested the use of an iconic species, the Greater Flamingo, as a lens for participatory mapping to render explicit the socio-cultural values attributed in a landscape. Spatial information on six landscape values in a biodiversity hotspot, the Camargue Biosphere Reserve (southern France) was collected from 113 participants through surveys, interviews and workshops. This data was geolocated through a SoftGIS methodology to map and quantify the overlap of bivariate hotspots identifying value concurrence. The most frequent values recorded through total number of polygons and surface areas were wilderness and recreation. The least frequently mapped values were economic loss and biodiversity.

There was frequent concurrence between biodiversity and aesthetic values especially in wetlands (lagoons, salt flats and sea). There was also frequent concurrence between biodiversity and recreational values with more overlap in sites with easy access (along roads and public areas). Our results show that using an iconic species is an effective way to render explicit spatial variations in the values attributed to a landscape and to identify concurrence of values, thus enabling integration of multiple landscape values in conservation planning how to cite :

Introduction

Human wildlife con icts are increasing and new pathways are needed to mitigate them in order to conciliate biodiversity conservation with human livelihoods and human well-being [START_REF] Redpath | Understanding and managing conservation conflicts[END_REF]. Increased public participation in planning and management that integrates socio-cultural values could e ectively overcome this challenge [START_REF] Cole | Limits of acceptable change and natural resources planning: When is LAC useful, when is it not? United states department of agriculture forest service general technical report[END_REF][START_REF] Ernoul | Governance in integrated coastal zone management: A social networks analysis of cross-scale collaboration[END_REF]. Engaging civil society through participatory surveys on landscape values (Brown & Weber, 2011a;[START_REF] Wardell-Johnson | A sense of place: Valuing landscapes in the condamine headwaters[END_REF] provides a promising avenue to integrate social and ecological values for con ict mitigation.

Visualization techniques such as mapping are useful tools for environmental management. They can be used to prioritize investments and foster strategic planning [START_REF] Pettit | Identifying strengths and weaknesses of landscape visualisation for effective communication of future alternatives[END_REF]. The same landscape can be valued for multiple reasons, creating overlaps or hotspots of values [START_REF] Stephenson | The Cultural Values Model: An integrated approach to values in landscapes[END_REF]. Participatory GIS provides a unique approach for engaging civil society in decision-making by integrating local knowledge with complex spatial information [START_REF] Lasimbang | Participatory community mapping: A gender perspective[END_REF][START_REF] Sieber | Public participation geographic information systems: A literature review and framework[END_REF]. SoftGIS approaches gather and analyze local experiential knowledge integrating GIS with quantitative techniques [START_REF] Rantanen | The SoftGIS approach to local knowledge[END_REF]. This process generates information from individuals and populations about the way they value their own living environment, providing local communities (and local knowledge sources) with an active voice in planning and management [START_REF] Kahila-Tani | Let the citizens map-public participation GIS as a planning support system in the Helsinki master plan process[END_REF]. This participatory mapping of landscape values has drawn on approaches developed by Brown et al. [START_REF] Brown | The relationship between place attachment and landscape values: Toward mapping place attachment[END_REF][START_REF] Brown | Public participation GIS: A new method for national park planning[END_REF][START_REF] Brown | Mapping spatial attributes in survey research for natural resource Management: Methods and applications[END_REF] in which 14 landscape values were identi ed and tested: aesthetic, biodiversity, cultural, learning, therapeutic, spiritual, future, economic, historic, recreation, l ife sustaining, subsistence, intrinsic and wilderness values. This valuation scheme retrieves positive (i.e. bene ts obtained from landscapes) and negative values (i.e. degrading processes or threats) [START_REF] Raymond | Mapping community values for natural capital and ecosystem services[END_REF].Species, landscapes, and ecosystems are valued di erently by individuals and across human populations. Landscapes are important for socio-cultural and ecological values [START_REF] Martínez Pastur | Spatial patterns of cultural ecosystem services provision in Southern Patagonia[END_REF][START_REF] Van Riper | Capturing multiple values of ecosystem services shaped by environmental worldviews: A spatial analysis[END_REF] and understanding the overlap of these values can help conservation professionals to design strategies to address potential valueconflicts [START_REF] Bryan | Comparing spatially explicit ecological and social values for natural areas to identify effective conservation Strategies: Spatial comparison of social and ecological values[END_REF][START_REF] Moore | Identifying conflict potential in a coastal and marine environment using participatory mapping[END_REF]. Iconic species are widely used as symbols to stimulate conservation awareness and action [START_REF] Simberloff | Flagships, umbrellas, and keystones: Is single-species management passé in the landscape era?[END_REF]. Marketing and communication experts have used these values to advance conservation objectives [START_REF] Douglas | Flagships or Battleships: Deconstructing the relationship between social conflict and conservation flagship species[END_REF]. Although there has been an increasing amount of work on landscape value analysis (see [START_REF] Moore | Identifying conflict potential in a coastal and marine environment using participatory mapping[END_REF][START_REF] Ramirez-Gomez | Participatory mapping to identify indigenous community use zones: Implications for conservation planning in southern Suriname[END_REF][START_REF] Zolkafli | Bridging the knowledge divide between public and experts using PGIS for land use planning in Malaysia[END_REF], mapping has not previously focused on an iconic species to identify concurrence of social and ecological landscape values in relation to conservation management. Given that conservation planning and management should account for the values expressed by the local human populations (Brown & Weber, 2012) within a landscape context [START_REF] Ernoul | Adapting international conservation strategies to local context: Perceptions of biodiversity values and management responsibility in two mediterranean deltas[END_REF], we tested the use of participatory values mapping using flamingos as a proxy to reveal spatial variations in landscape valuation. The Greater Flamingo (Phoenicopterus roseus, hereafter flamingo) is an iconic species for the Camargue (Rhône Delta) in southern France [START_REF] Johnson | The greater flamingo (T & a poyser)[END_REF]. Flamingos have thrived in the Camargue landscapes for over six centuries but concerns raised in the 1960s resulted in a conservation program to support breeding in the Camargue. The program was a success and increased the flamingo population across the Mediterranean basin [START_REF] Johnson | The greater flamingo (T & a poyser)[END_REF]; however, global changes and conflicts with other land-uses have the potential to compromise this success [START_REF] Béchet | Global economy interacts with climate change to jeopardize species conservation: The case of the greater flamingo in the mediterranean and west Africa[END_REF]. This research aimed to identify value hotspots linked to flamingos in the Camargue to support effective conservation planning and landscape management. The results demonstrate the value of focusing on an iconic species as a lens for participatory mapping in conservation planning.

Methodology

Study area and species

The Camargue is a Biosphere Reserve (UNESCO) recognized for its human and ecological landscape values. It is also one of the largest wetlands in the Mediterranean basin and recognized as important in the staging, wintering and breeding of water birds (Ramsar, 1986, p. 4). The delta forms a triangle of 150 000 ha encompassing three distinct management zones: Grande Camargue, Petite Camargue and the Plan du Bourg (Fig. 1).

The greater flamingo's range spans Africa, the Middle East and Southern Europe. It is in Annex 1 of the Wild Birds Directive of the European Union (European Union, 2009) and in Appendix II of the Bern Convention (strictly protected speies) (Council of Europe, 1979).

The species is not globally threatened, but it is considered of conservation concern given its dependence on a limited number of wetlands [START_REF] Johnson | The greater flamingo (T & a poyser)[END_REF]). An artificial breeding island was constructed in the salt pans of Salin-de-Giraud in 1970 in response to concerns about a declining flamingo population in the Mediterranean basin. The island created ideal breeding conditions in the Camargue, increasing the breeding population to an average of 13 000 pairs per year [START_REF] Béchet | Anthropogenic and environmental determinants of Greater Flamingo Phoenicopterus roseus breeding numbers and productivity in the Camargue (Rhone delta, southern France)[END_REF][START_REF] Béchet | Greater flamingos stop breeding in the Camargue (souther France) in 2007, for the first time in 38 years; the beginning of a new era? In flamingo[END_REF][START_REF] Bechet | Global economy interacts with climate change to jeopardize species conservation: The case of the greater flamingo in the mediterranean and west Africa[END_REF]. Despite abundant natural habitat, flamingos have evolved their behavior in response to improved foraging condi tions in agricultural fields. This has resulted in significant economic loss for rice producers, causing local conflicts between environmental and economic priorities [START_REF] Ernoul | Diagnostic de l'échec de la contractualisation des mesures agri-environnementales pour réduire les incursions des Flamants dans les rizières de Camargue (France)[END_REF][START_REF] Ernoul | Limits to agri-environmental schemes uptake to mitigate human-wildlife conflict: Lessons learned from flamingos in the Camargue, southern France[END_REF][START_REF] Tourenq | Are ricefields a good alternative to natural marshes for waterbird communities in the Camargue, southern France?[END_REF].

A series of global changes have impacted the breeding colony over the last decade including the reduction of salt production [START_REF] Béchet | Global economy interacts with climate change to jeopardize species conservation: The case of the greater flamingo in the mediterranean and west Africa[END_REF], changes in ownership of parts of the salt pans [START_REF] Ernoul | Representing the greater flamingo in southern France: A semantic analysis of newspaper articles showing change over time[END_REF] and agricultural intensification [START_REF] Pernollet | Seed density and waterfowl use of rice fields in Camargue, France: Seed density and use of rice fields by ducks[END_REF] exacerbating humanflamingo conflicts. These changes have caused greater variation in annual and seasonal water levels, reducing flamingo breeding conditions some years. In 2014, water levels around the flamingo island were so low that terrestrial predators (i.e. fox) were able to reach the colony causing flamingos to abandon their breeding site in Salin-de-Giraud and relocate to Aigues-Mortes (Fig. 1). In 2015, new hydraulic infrastructure and heavy winter rains restored the conditions and the flamingo colony returned to breed successfully in the salt pans of Salin-de-Giraud. The vulnerability of this iconic species to a range of humaninduced conditions demonstrates the need to understand the potential conflicts in land-use and landscape value for conservation planning to be effective.

Sample

Although only 25 participants are necessary for polygon analysis in participatory mapping [START_REF] Brown | An evaluation of the use of points versus polygons in public participation geographic information systems using quasi-experimental design and Monte Carlo simulation[END_REF], we increased our sample size to include a larger representation of stakeholder groups and geographic zones. An effort was made to ensure participation of landusers and socioprofessional groups (rice farmers, hunters, herders, tourism industry, site managers, scientists and local government authorities) with interest in the three zones of the Camargue (Greater Camargue, Lesser Camargue and the Plan du Bourg). We applied three approaches for collecting spatial information: participatory workshops (with open participation and meetings publicized in local newspapers), internet surveys (distributed by the Natural Regional Park of the Camargue (PNRC) and the Tour du Valat Mediterranean Wetlands Research Institute (TdV)) and face-to-face delivery by the researchers. The first two approaches are considered volunteer geographic information (Brown, Weber, & de Bie, 2014a) as compared to the face-to-face delivery which sampled participants strategically to ensure a population cross-section based on interests, socio-professional occupation or geographic location (Wardell- Johnson, 2011, pp. 15-29). The participants in workshops and face-to-face delivery used a facilitated mapping approach while the internet participants used a self-administered approach. Participatory workshops were organized by the PNRC in three villages: Salin-de-Giraud, Mas Thibert and Grau-du-Roi (Fig. 1). There were between 8 and 15 participants in each workshop (total of 28 participants). The workshops began with an introduction to flamingo conservation in the Camargue by a local expert (AB), then each participant completed a facilitated questionnaire and values-mapping.

Internet surveys provided the opportunity for a 'volunteer public' to participate in the study outside the immediate influence of other respondents present in a group work setting (Brown, Kelly, & Whitall, 2014b). Information was made available through the TdV and the PNRC. A total of 52 individuals participated in the internet survey. To ensure the representation of all of the identified interests, socio-professional groups and geographic sectors, we delivered the survey face-to-face for the categories that were under-represented (geographic and socio-professional). The individuals were selected through local social networks. Face-to-face delivery attracted 33 individual responses. In total, 113 individuals participated in the mapping with socio-demographic information collected for each participant.

Values mapping of the iconic species

We used a values mapping methodology developed by [START_REF] Brown | Public participation GIS: A new method for use in national forest planning[END_REF] and tested by members of the team both in Australia (Wardell- [START_REF] Wardell-Johnson | A sense of place: Valuing landscapes in the condamine headwaters[END_REF] and in the Camargue (Ernoul & WardellJohnson, 2014). A subset of the 14 values was selected for its relevance to flamingos and the potential to delineate these values on a map geographically within the landscape. Four values (Recreation, Aesthetic, Biodiversity and Economic) were selected for this study along with two additional values: wilderness, and economic risks which were Required to reflect issues at stake in the Camargue (Table 1).

Maptionnaire (https://maptionnaire.com) was used in all workshop settings, face-to-face questionnaire deliveries and internet surveys to map values. Maptionnaire is an interactive cloud service that creates, analyzes and publishes map-based questionnaires with an editing tool (Kahila & Kyttä, 2009). This online software provided access to multiple map scales, customizable cartography and base map features. The online interaction requires no additional translation, reducing needs for digitization that often result in spatial error [START_REF] Brown | Evaluation of an online (opt-in) panel for public participation geographic information systems surveys[END_REF]. Additional time and logistics were required to find appropriate workshop locations with internet access for the use of online software. Each participant had the opportunity to create a polygon delimiting an area corresponding to one or more of the selected values (not limited to the Camargue geographical area). No limits were given for the size or number of polygons for each value. Participants could choose not to map one or several values.

Data analysis

We superimposed all value-polygons (579) identified by the participants over a vector cell grid (500 m by 500 m), creating vector cells of 25 ha for each value using MapInfo version 15. We then calculated the number of polygons inclu ded for each value in each vector cell. A rasterization of the total amount of polygons per value and per vector cell was computed, creating heat maps. Heat -maps use color combinations to represent scores from matrix outputs of multi-criteria analyses [START_REF] Karimi | Methods and participatory approaches for identifying social-ecological hotspots[END_REF]. Bivariate maps were produced for the values to identify value hotspots. Each value is represented by a unique color on each axe (Fig. 2). The axis represents a value or number of polygons. The diagonal represents identical values for each variable and is the result of the combination of the representative colors for each variable taken individually. Using the bivariate maps, we calculated the spatial concurrence of each combination of values two by two (as identified by at least half of the participants) [START_REF] Karimi | Methods and participatory approaches for identifying social-ecological hotspots[END_REF]. Each value is represented by a unique color on each axe (Fig. 2). The axis represents the percentage of participants which have included the given quadrat within their polygon for each value. The diagonal represents identical values for each variable and is the result of the combination of the representative colors for each vari able taken individually.

Principal component analysis was used to convert the mapped polygons into a set of values of line arly uncorrelated variables. Because the components are linear combinations, the component scores were then statistically analyzed. Using GeoDa, we determined the Eig envectors values for each of the landscape values (https:// geodacenter.github.io/index.html) to calculate the relationship between values. Finally we compared the results for each delivery approach.

Tableau 1List and definitions of the landscape values used in the mapping exercise in the Camargue (based on Brown & Reed, 2009).

Figure 2 Conceptual model of bivariate heat maps used in the Camargue

Results

We characterize the participants in groups according to their sociodemographic information (3.1), then we show the relative spatial attribute of each landscape value (3.2) and evaluate the spatial concurrence of bivariate hotspots (3.3). Finally we compare the results obtained according to the three participatory mapping approaches.

Socio-demographic description of participants

Of the 113 individuals that participated in the research, 31% were from a workshop setting, 32% through face-to-face deliveries and 37% through the internet site. There was a slightly higher participation of female participants (Females: 56%, Males: 44%) (Table 2). The majority (86%) of the participants were working age (between 25 and 64 years) with only a minimal participation from the retired community (8%). Most participants were residents in the Camargue (49%), Arles (26%) or within a 30 km radius of Arles (28%). The environmental sector (30%) was the most represented socio-professional group, followed by researchers (12%), services (including taxi drivers, nurses, waitresses, accountants) (12%) and private businesses (10%). Given the similarity in polygon distribution and concurrence for the three different methodological approaches, we integrated all of the data for spatial analysis.

Spatial attributes of landscape values

The most frequently mapped values were wilderness and recreation (polygons and surface area) (Fig. 3). The least frequently mapped values were economic loss and biodiversity (polygons and surface area).

Evaluation of landscape values hotspots

We mapped and quantified the spatial concurrence for each pair of landscape variables to determine geographic overlap between values (Fig. 4a andb,c,d ande).

Economic risks were mainly identified in fresh water zones in association with rice production. Economic gain was primarily located in coastal towns (Aigues-Mortes, Saintes-Maries de la Mer and Salin-de-Giraud), coastal zones and protected areas with organized tourism or commerce (Fig. 4a). Aesthetic values spanned most of the Camargue landscape, with strong concurrence between recreational and aesthetic values in coastal zones, areas accessible to the public, beaches and roads surrounding protected areas (Fig. 4b). The highest levels of concurrence in recreational and wilderness values were in the zones surrounding the accessible protected areas (Fig. 4c). There was a stronger wilderness value in protected areas and a higher recreational value in the coastal areas and main towns. There was a high concurrence between biodiversity and aesthetic values, especially in wetlands (lagoons, salt flats and sea) (Fig. 4d). Aesthetic value comprised a larger area than biodiversity value. There were no areas with biodiversity value that did not also have an aesthetic value. There was a strong concurrence between biodiversity and recreational values with stronger overlap in the areas with easy access (along roads and public areas) (Fig. 4e). The coastal zone had higher value for recreation when compared to biodiversity value.

Figure 3Number of polygons and total area of polygons delimiting the location of the values attributed to landscape used by flamingos in

the Camargue (surface areas are given in km2).

Tableau 2 Socio-demographic information on the participants involved in the landscape values mapping exercise in the Camargue

Bivariate maps and spatial concurrence (Table 3) demonstrated strongest overlap between biodiversity and aesthetic values (43%), followed by aesthetic and wilderness values (42%), and then biodiversity and wilderness values (41%). Recreational values had the least correlation (17%) with economic gain as compared to the other values.

There was very little concurrence between economic loss and other variables, with the exception of economic loss and biodiver sity (18%). The PCA analysis carried out using the GeoDa software showed the following trends (Eigenvector values > 0,5): PC1: Recreation (0.55), E conomic gain (0.56), Biodiversity (0.57), PC2: Economic loss (0.8), Aesthetic (-0.66), PC3: Economic loss (-0.57), Aesthetic (0.81), PC4: Recreation (-0.76), Economic gain (0.63) and PC5: Economic gain (0.52), Biodiversity (0.8). The squared correlations showed strong links between Recreation (0.87), Economic gain (0.9) and Biodiversity (0.92) in PC1 as opposed to Economic loss (0.63) in PC2. This indicated a strong positive relationship in the perception for recreational, biodiversity and aesthetic values.

The comparison of number of polygons selected according to the three survey approaches (workshop, face-to-face delivery and internet), allowed us to weight the contribution of each survey approach (Fig. 5). Workshop participants consistently designated more polygons followed by face-to-face delivery and internet participants. This was mostly likely the result of interactions with other participants in the workshop setting. Thus the workshop setting could reflect a more generalized valuing. However, considering that concurrence between values did not change according to survey approach, the generalized valuing did not nuance the individual values in a landscape context but offered strength through methodological triangulation in instrument delivery.

Discussion and conclusions

Using geographic information systems to map landscape values has been tested and shown to be effective for landscape planning [START_REF] Gallo | Exploring urban parks and their peripheral food environments using a case study approach: Young people and obesogenic environments[END_REF][START_REF] Moore | Identifying conflict potential in a coastal and marine environment using participatory mapping[END_REF][START_REF] Ramirez-Gomez | Participatory mapping to identify indigenous community use zones: Implications for conservation planning in southern Suriname[END_REF]. Here, participatory mapping was used to test the worth of using iconic species in understanding the co-occurrence of individual values in a landscape. The values-mapping of iconic species stimulates public participation potentially generating management approaches that integrate ecological needs of the species (and associated habitats and ecosystems) to complement the values of the human population.

We found that landscape values focusing on an iconic species were not randomly distributed, but rather created a pattern of hotspots in very specific locations. This correlates with similar participatory mapping research focusing on landscapes in general [START_REF] Brown | Public participation GIS: A new method for use in national forest planning[END_REF][START_REF] Kahila-Tani | Let the citizens map-public participation GIS as a planning support system in the Helsinki master plan process[END_REF]. Weighting the values by the number of responses per pixel, allowed us to determine which landscape categories were most frequently valued for each site. The maps demonstrated that aesthetic value is predominant in more accessible areas (along roadways and beaches) indicating that human access is a key to this value. The link between aesthetics and access could be attributed to the fact that when people can visit a site, they are exposed to the beauty (or lack of) in that place. Land with restricted access does not allow people to visit, thus the aesthetic values are not nominated. This would indicate that if areas are managed for aesthetics, recreation and wilderness, attention must also be given to ensure some access to human populations to support the other values. The relationship between aesthetics and accessibility conveys an important message for land manager s: increasing public access could increase values associated with those places but must be appropriately managed so as not to threaten other values such as wilderness or biodiversity [START_REF] Bennett | Why local people do not support conservation: Community perceptions of marine protected area livelihood impacts, governance and management in Thailand[END_REF].

The identification of hotspots provides a way to quantify, visualize, and geo-locate the values underpinning management options by integrating multiple landscape values. Similar to [START_REF] Harrison | Linkages between biodiversity attributes and ecosystem services: A systematic review[END_REF], we identified larger surface areas and higher density of polygons for aesthetics, recreation and wilderness. These values were often linked together in our research; however, Qiu, Linderg & Nielsen (2013) suggest that the relationship may not always be positively correlated. The economic losses due to biodiversity conservation [START_REF] Sukumar | The Asian Elphant: Ecology and management[END_REF] or restricted recreational activities [START_REF] Mclachlan | Sandy beach conservation and recreation: Guidelines for optimising management strategies for multi-purpose use[END_REF] are often cited as causes of conservation conflict [START_REF] Brown | Assessing the value of public lands using public participation GIS (PPGIS) and social landscape metrics[END_REF]. In our research, we clearly identified concurrence between biodiversity and economic loss and biodiversity and recreation. These hotspots can alert land managers to potential areas of conflict. Integration of participatory processes in decision-making could reduce these risks and promote effective engagement of socioeconomic systems and improve mitigation actions [START_REF] Jones | The study of human values in understanding and managing social-ecological systems[END_REF]. Mapping landscape values provides land managers with planning tools and evidence to minimize land-use conflict and to develop more effective conservation planning.

Economic gain and economic risk values are often a point of contention for land management [START_REF] Zia | Cross-Scale value trade-offs in managing social-ecological Systems: The politics of scale in ruaha national park, Tanzania[END_REF]. Despite increasing recognition of the importance of economic contributions of public land protected for biodiversity values, few studies document the soci o-economic value of protected areas [START_REF] Heagney | Socio-economic benefits from protected areas in southeastern Australia[END_REF]. Further research into the links between economic values and economic risks on both public protected lands and private lands would provide useful information for site managers to understand conflicts related to biodiversity and economic value. This would be an effective means of minimizing perceived economic risk relating to biodiversity conservation in landscapes with multiple uses such as Biosphere reserves.

Similar to previous work by Brown et al. (2014), we found that workshop participants (volunteer and facilitated participants) con sistently selected more polygons for each landscape value compared to internet (volunteer and self -administered) and face-to-face delivery (selected and facilitated) approaches. However, despite the difference in polygon numbers, there were not important differences in landscape value concurrence with the three approaches. Given the importance of tourism in the Camargue, it is important to note t hat our sampling methodology did not include tourists. Future studies considering tourist values in the Camargue would be a valuable complement to these re sults.

Effective planning for conservation of biodiversity requires approaches that integrate the plurality of stakeholder values. Iconic species distil the characteristics of socio-ecological interdependence, providing significant value to integrative conservation strategies in regional planning and management design [START_REF] Mathevet | Protected areas and their surrounding territory: Socioecological systems in the context of ecological solidarity[END_REF]. In conclusion, our study demonstrates that iconic species are a useful lens for participatory mapping of landscape values and could potentially spur interest and focus attention in con servation planning for other sites.

Figure 1 .

 1 Figure 1. Location of the study site (total surface area is 860 km2 of land and 343 km2 of marine protected area).

Tableau 3

 3 Spatial concurrence of landscape values in Camargue (values with the highest spatial concurrence are highlighted in yellow and lowest are shown in blue).

Figure 4 a

 4 Figure 4 a: Bivariate heat map of economic loss (blue) and economic gain (pink) landscape values in Camargue. b: Bivariate heat map of aesthetic (blue) and recreation (pink) landscape values in Camargue. c: Bivariate heat map of wilderness (blue) and recreation (p

Acknowledgments

This study was funded by the Fondation de France, Fondation MAVA and Fondation Tour du Valat. We thank Tatiana Fuentes, Katia Lombardini and Camille Muranyi-Kovacs for their support in the participatory workshops.


Paul Acker

Charlotte Francesiaz

Arnaud Béchet

Nicolas Sadoul

Catherine M Lessells

Agata S Pijl

Aurélien Besnard

Insights on dispersal and recruitment paradigms: sexand age-dependent variations in a nomadic breeder

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

When and where animals breed are 'two sides of the same coin' [START_REF] Ens | The despotic distribution and deferred maturity: two sides of the same coin[END_REF]) that shape short-and long-term fitness prospects [START_REF] Bowler | Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics[END_REF][START_REF]Early development, recruitment and life history trajectory in long-lived birds[END_REF]. Recruitment to a breeding population and dispersal are thus pivotal and intimately linked processes in life histories. They also have major consequences on population dynamics and gene flow [START_REF] Charlesworth | Evolution in age-structured populations[END_REF][START_REF] Bowler | Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics[END_REF].

Early recruitment should be selected when it maximizes the expected number of breeding attempts over the lifespan [START_REF] Charlesworth | Evolution in age-structured populations[END_REF]. However, delayed recruitment may be favoured when it limits the cost of first reproduction (e.g., [START_REF] Desprez | Age-specific cost of first reproduction in female southern elephant seals[END_REF]) and allows behavioural maturation (gains in competitive or foraging skills) to increase the chance of acquiring a breeding site of good quality and producing offspring [START_REF] Charlesworth | Evolution in age-structured populations[END_REF][START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF]). Prospecting, competing, and queuing for good-quality sites may also result in recruitment delays [START_REF] Ens | The despotic distribution and deferred maturity: two sides of the same coin[END_REF][START_REF] Boulinier | The use of conspecific reproductive success for breeding patch selection in terrestrial migratory species[END_REF].

Heterogeneity in individual tactics may yield substantial variations in recruitment age; this is commonly observed in most long-lived animals (e.g., birds: [START_REF] Becker | The role of intrinsic factors for the recruitment process in long-lived birds[END_REF][START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF]mammals: Martin and FestaBianchet 2012;[START_REF] Desprez | Age-specific cost of first reproduction in female southern elephant seals[END_REF]reptiles: Congdon et al. 1993). The optimal recruitment age depends on individual competitive abilities and habitat quality (which may depend on density, food availability, etc.) and their interaction (birds: [START_REF] Van De Pol | Variation in habitat choice and delayed reproduction: adaptive queuing strategies or individual quality differences?[END_REF][START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF]mammals: Komers et al. 1997;[START_REF] Gaillard | Temporal variation in fitness components and population dynamics of large herbivores[END_REF]. In addition, due to asymmetric costs of reproduction [START_REF] Th | The evolution of parental care[END_REF]e.g., in birds: Williams 2005; mammals: [START_REF] Michener | Differential costs of reproductive effort for male and female richardson's ground squirrels[END_REF], sex differences in recruitment age might evolve through different optimal ages of behavioural maturity [START_REF] Kim | Effects of recruiting age on senescence, lifespan and lifetime reproductive success in a long-lived seabird[END_REF].

Dispersal is expected to be a response to inbreeding risk, competition, and spatiotemporal variability in breeding habitat quality [START_REF] Hamilton | Dispersal in stable habitats[END_REF][START_REF] Mcpeek | The evolution of dispersal in spatially and temporally varying environments[END_REF]reviewed in Bowler and Benton 2005). However, dispersal entails costs (reviewed in [START_REF] Bonte | Costs of dispersal[END_REF]) such as energetic expenditure, time spent in prospection or transfer, predation or damage risk, and opportunity costs of choosing another breeding site (e.g., loss of familiarity-including dominance on a territory).

These costs and benefits of dispersal may also depend on individual characteristics [START_REF] Bowler | Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics[END_REF][START_REF] Bonte | Costs of dispersal[END_REF]. Higher natal than breeding dispersal and sexbiased dispersal can be favoured through kin competition or inbreeding avoidance [START_REF] Greenwood | Mating systems, philopatry and dispersal in birds and mammals[END_REF][START_REF] Perrin | Local competition, inbreeding, and the evolution of sex-biased dispersal[END_REF]. Proximate explanations for decreased dispersal propensity with age are generally an increase in competitiveness or advantages from territory ownership with age and experience [START_REF] Greenwood | Mating systems, philopatry and dispersal in birds and mammals[END_REF][START_REF] Bowler | Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics[END_REF][START_REF] Piper | Making habitat selection more "familiar": a review[END_REF]). Proximate explanations for sex-biased dispersal are generally mating system characteristics: one sex being more involved in the acquisition and maintenance of a territory (e.g., males in most birds; females in most mammals: [START_REF] Greenwood | Mating systems, philopatry and dispersal in birds and mammals[END_REF][START_REF] Trochet | Evolution of sexbiased dispersal[END_REF]. Accordingly, the territorial sex benefits more from remaining in the same familiar location than from dispersing, while the other sex benefits more from dispersing to search for other mating opportunities (and to avoid kin competition and inbreeding).

To date, most recruitment and dispersal studies have focused on species that evolved in relatively stable environments in which breeding patch quality does not vary much over the timescale of an individual's life. Such environments provide sufficient habitat predictability to promote fidelity to breeding patches and year-to-year territory ownership within the patch (e.g., over many taxa, and theoretical model [START_REF] Switzer | Site fidelity in predictable and unpredictable habitats[END_REF]in birds: McNicholl 1975;[START_REF] Acker | Breeding habitat selection across spatial scales: is grass always greener on the other side?[END_REF]in mammals: Lurz et al. 1997). This context often including some spatiotemporal heterogeneity of the environment-entails harsh competition for acquiring and maintaining ownership on a high-quality territory (e.g., in birds and mammals [START_REF] Cadiou | Prospecting in the kittiwake, Rissa tridactyla: different behavioral patterns and the role of squatting in recruitment[END_REF][START_REF] Kokko | Competition for breeding sites and site-dependent population regulation in a highly colonial seabird, the common guillemot Uria aalge[END_REF][START_REF] Vanpé | Age-specific variation in male breeding success of a territorial ungulate species, the European roe deer[END_REF][START_REF] Stockley | Female competition and its evolutionary consequences in mammals[END_REF]. This is a major constraint inducing asymmetry in costs of dispersal or recruitment, which drives the sex-and age-dependent variations exposed above.

In contrast, such cost asymmetry may be relaxed when there is no advantage in breeding on the same patch over the years: that is, in unstable, ephemeral environments where year-to-year predictability of habitat quality is weak, such as temporary wetlands [START_REF] Mcnicholl | Larid site tenacity and group adherence in relation to habitat[END_REF][START_REF] Béchet | Global economy interacts with climate change to jeopardize species conservation: the case of the greater flamingo in the Mediterranean and West Africa[END_REF] or (semi-)arid regions [START_REF] Dean | The distribution and biology of nomadic birds in the Karoo, South Africa[END_REF]. High dispersal propensity is then expected [START_REF] Travis | Habitat persistence, habitat availability and the evolution of dispersal[END_REF][START_REF] Friedenberg | Experimental evolution of dispersal in spatiotemporally variable microcosms[END_REF] with the possible evolution of 'nomadic breeding' patterns (mostly described in birds; e.g., in [START_REF] Greenwood | The natal and breeding dispersal of birds[END_REF][START_REF] Crawford | Breeding nomadism in southern African seabirds-constraints, causes and conservation[END_REF].

Here, we assessed the extent of individual variation in dispersal and recruitment in a colonial bird with a nomadic breeding strategy. In avian colonial species, breeding terri-tories are reduced to the nest site and separated from undefended foraging resources [START_REF] Evans | Information use in colonial living[END_REF]. These territories are still heterogeneous in quality, due to, e.g., predation risk or parasite infestation [START_REF] Boulinier | Spatial and temporal variation of factors affecting breeding habitat quality in colonial birds: some consequences for dispersal and habitat selection[END_REF]. The most dispersal-prone species are typically found breeding in unstable habitats such as islets or banks in lagoons and rivers where droughts or floods frequently occur [START_REF] Mcnicholl | Larid site tenacity and group adherence in relation to habitat[END_REF][START_REF] Oro | Comparing demographic parameters for philopatric and immigrant individuals in a longlived bird adapted to unstable habitats[END_REF]. We focused on such a species, the slender-billed gull (Chroicocephalus genei) and analyzed the life histories of 3479 individuals (2392 genetically sexed, 1289 males and 1103 females) over 13 years along the French Mediterranean coast. We used multievent capture-recapture models taking breeding status uncertainty into account [START_REF] Pradel | Multievent: an extension of multistate capturerecapture models to uncertain states[END_REF] to investigate the effect of breeding status (pre-breeder or breeder), age, and sex on dispersal and recruitment at a regional scale (i.e., over all colonies of the study area).

In nomadic breeders, including slender-billed gulls, the costs of dispersal and early recruitment associated with competitiveness or local familiarity for territory maintenance over the years should be largely relaxed. Though individuals still have to obtain a mate and breeding territory, ownership is not maintained over the years: territories do not bear any long-standing value (see [START_REF] Piper | Making habitat selection more "familiar": a review[END_REF]. Furthermore, breeding nomadism should induce low risk of kin competition and inbreeding. Assuming that competition for holding a breeding territory over the years has, indeed, a prevailing role in individual variations in dispersal and recruitment as emphasized above, we expected (H1) age or sex differences in dispersal propensity to be attenuated and, perhaps, absent (see [START_REF] Greenwood | The natal and breeding dispersal of birds[END_REF]. We further expected (H2) low recruitment delays and low variation in recruitment age, and potentially (H3) sex-biased recruitment driven by asymmetry in costs of reproduction rather than by asymmetry in costs of territoriality. In the slender-billed gull, which is monogamous with biparental care [START_REF] Besnard | Evolution de l'élevage des poussins en crèche chez les laridés[END_REF], females might recruit later due to the costs of egg production that would not be compensated for in males by territoriality costs.

Materials and methods Study area and species

The slender-billed gull distribution extends from Western India to Senegal, the Caspian, Black, and Mediterranean Seas [START_REF] Del Hoyo | Handbook of the birds of the world[END_REF]). In the Western Mediterranean, strong immigration and emigration drive population dynamics and generate substantial variations in annual breeding numbers [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF][START_REF] Sanz-Aguilar | Living on the edge: demography of the slender-billed gull in the western mediterranean[END_REF]. Slender-billed gulls breed on isolated islands in temporary wetlands, brackish lagoons, and saltpans. Just after hatching, chicks leave the nest to join a crèche, a behaviour considered to be an adaptation to water-level unpredictability throughout the breeding season [START_REF] Besnard | A model for the evolution of crèching behaviour in gulls[END_REF]. Because chick rearing occurs in crèches and nests are closely packed [START_REF] Fasola | Nest habitat selection by eight synoptic species of Mediterranean Gulls and Terns[END_REF], heterogeneity in nest-territory quality is reduced to a simple risk gradient from the edge to the core of the nesting area during incubation (e.g., due to predation: [START_REF] Brunton | Impacts of predators: center nests are less successful than edge nests in a large nesting colony of Least Terns[END_REF].

From 1998 to 2010, exhaustive survey of the French Mediterranean coast allowed locating all slender-billed gull colonies. We defined a 'colony' as the group of breeding gulls at a single island site in a given year. Over 1998-2010, 2-10 colony sites were occupied each year. A total of 60 colonies were recorded on 45 different sites (Fig. 1), with a high colony-site turnover rate (i.e., between-years change in occupied sites resulting from establishment or desertion; [START_REF] Erwin | Colony site dynamics and habitat use in Atlantic coast seabirds[END_REF]) of 0.82 (Online Appendix S1). Because almost all colony sites were abandoned from 1 year to the next, it was impracticable to consider individual variation in site-specific dispersal rates. We thus combined all colonies as a single breeding location to explore recruitment and dispersal in and out of the study area. Annual breeding population size in the area varied over 209-877 pairs and reproductive success varied over 0.11-1.26 fledged chicks per nest (average: 0.72; Online Appendix S1: Fig. S1; [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF].

Data collection

From 1997 onward, more than 90% of slender-billed gulls born in France have been marked just before fledging with rings bearing an alphanumeric code (easily readable with a telescope up to 100 m; [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF]. To date, the oldest bird in our data set is 20 years old (the age of the ringing-resighting programme), but slender-billed gulls can probably live even longer as do larids of similar size (oldest recorded individuals are usually ca. 30 years old: [START_REF] Fransson | EURING list of longevity records for European birds[END_REF]; and see Table 1). Sex was genetically determined from a down or feather sample using standard molecular techniques [START_REF] Griffiths | A DNA test to sex most birds[END_REF]. Resightings including behavioural observations were conducted from blinds at each colony every day during several hours from arrival to departure of the birds. Apart from one colony in 2003, each colony was intensively monitored. An individual may have been resighted several times per season, but all these observations were collapsed into a single annual resighting. To build capture-recapture histories, resightings were coded as a function of behavioural observations providing the highest level of information on breeding status (see below).

Modelling

We used multievent capture-recapture models [START_REF] Pradel | Multievent: an extension of multistate capturerecapture models to uncertain states[END_REF] to investigate recruitment to the study area and dispersal through temporary emigration (i.e., dispersal was modelled as the probability of leaving and coming back to the study area where ringing and resighting occurred; [START_REF] Schaub | Estimating survival and temporary emigration in the multistate capturerecapture framework[END_REF]Fig. 2, Online Appendix S2).

Each year, an individual was distinguished as being in one of the following states: (a) pre-breeder (individual that has not yet reproduced) inside the study area, (b) pre-breeder outside the area, (c) breeder inside the area, (d) breeder outside the area, or (e) dead or permanently emigrated. We then sequenced the inter-annual transition between states into three successive steps (i.e., transition probability was expressed as a product of conditional probabilities) following the natural order of post-breeding census: (i) local survival, (ii) movement (i.e., temporary emigration), and (iii) local recruitment (Fig. 2).

Multievent models allow dealing with imperfect detection and uncertainty in breeding state assessment during field observation [START_REF] Pradel | Multievent: an extension of multistate capturerecapture models to uncertain states[END_REF]. Within this framework, individual states are not directly observed but can be inferred from observation events (Fig. 2). Each annual occasion in an individual's capture-recapture history was coded as one of five possible observation events, reflecting to some extent its underlying breeding status (breeding or non-breeding): (i) 'not resighted', (ii) 'certain non-breeder' (only fledglings at ringing), (iii) 'uncertain breeder' (individuals observed alive but without any expected breeding behaviour), (iv) 'possible breeder' (individuals either manipulating nest material, attempting copulation, begging to, being fed by, or feeding another adult, or being begged by or accompanying a chick), and (v) 'certain breeder' (individuals incubating, replacing its partner at the nest or feeding a chick) (see Fig. 2). For each individual state, the probability of each observation event was modelled as a product of conditional probabilities: detection (i.e., resighting probability) and assignment (i.e., probability of being assigned to one of the four categories regarding breeding status assessment; Fig. 2) All capture-recapture histories started when the chick was ringed in the study area. To cope with identifiability issues due to the absence of resightings outside the study area [START_REF] Schaub | Estimating survival and temporary emigration in the multistate capturerecapture framework[END_REF], we considered that an individual had equal chances of local survival in step (i) whatever its location during the breeding season. In step (ii), an individual may stay in, emigrate from, stay outside or immigrate to the study area, depending on its previous location. In step (iii), pre-breeders may become breeders from age 2 (no individual in this species was ever observed breeding before that age). They could only recruit locally or remain pre-breeder (i.e., recruitment outside the study area was not modelled). Once recruited, individuals remain in the breeder state (i.e., reproductive skipping was not modelled: we assumed that already recruited individuals breeding or skipping the breeding attempt make similar decisions concerning attendance of breeding grounds inside or outside the area).

Goodness of fit

Because goodness-of-fit tests are currently not available for multievent capture-recapture models, we tested the goodness of fit of the Cormack-Jolly-Seber model (i.e., full-time dependence on survival and detection probability without multiple states and events; [START_REF] Pradel | Principles and interest of GOF tests for multistate capture-recapture models[END_REF] to our data using U-CARE v2.3.2 (Choquet et al. 2009a;Online Appendix S3). As in the previous analyses [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF], we found strong heterogeneity that may be due to transience (if local survival is agedependent; [START_REF] Pradel | Principles and interest of GOF tests for multistate capture-recapture models[END_REF]) and nonrandom temporary emigration (if the probability of being inside or outside the study area depends on the previous location; [START_REF] Schaub | Estimating survival and temporary emigration in the multistate capturerecapture framework[END_REF]). The disparities from the Cormack-Jolly-Seber hypotheses were handled using at least two age classes (first year and second year of life) in survival and temporary emigration parameters [START_REF] Pradel | Principles and interest of GOF tests for multistate capture-recapture models[END_REF][START_REF] Schaub | Estimating survival and temporary emigration in the multistate capturerecapture framework[END_REF]; Online Appendix S2, S3). Furthermore, there was no reason for heterogeneity in detection probability. Indeed, resighting is very easy: there is no obstructing vegetation, individuals hang at the periphery of the colony when they do not incubate, and birds are very active around the crèche.

6 One might question whether dispersal decisions are taken by groups of individuals from the same colony and how it could bias dispersal estimates. This issue remains unconsidered in the literature and falls beyond the scope of our paper. Nonetheless, a bias might exist if groups are assorted according to a variable of interest. Obviously, no colony is assorted by sex or breeding status. Colonies might be assorted by age, but this effect is probably diluted among the many cohorts and colonies constituting the data set. Further, analyses of dyadic associations in this data set suggest low group tenacity [START_REF] Francesiaz | Familiarity drives social philopatry in an obligate colonial breeder with weak interannual breeding-site fidelity[END_REF]).

Inference and model selection

Analyses were conducted using E-SURGE v1.8.19 (Choquet et al. 2009b). Model selection relied on the corrected Akaike Information Criterion (AICc; [START_REF] Johnson | Model selection in ecology and evolution[END_REF]. We considered the best model being the one with the lowest AICc. When there were nested models with AICc differing by less than 2 units, we selected the one with the lowest number of parameters to be as conservative as possible [START_REF] Burnham | Model selection and multimodel inference: a practical information-theoretic approach[END_REF]. Model building followed a step-wise approach. First, we conducted the analyses on the complete data set (3479 individuals) to select the best timeconstant model with agedependence, taking advantage of the largest data set as possible. This was done by reducing possible variations first on survival, and then on dispersal, recruitment, and finally on detection. Then, we conducted analyses on a reduced data set containing only individuals of known sex (2392 individuals, 1289 males and 1103 females): we fitted the model previously selected and started from this to select sex effects. The complete list of models is given in Online Appendix S4. At each step of model selection, we also selected time-varying models to check whether or not temporal variations revealed major differences that would have called into question the results from the timeconstant models (see Online Appendix S5).

When analyzing the complete data set, depending on the model, we considered 2-4 age classes in survival rates (e.g., two classes: age 1, >age 2; three classes: age 1, age 2, and >age 3), 2-4 age classes in dispersal (which also depends on individual breeding state; see above) and 1-5 age classes in recruitment (excluding yearlings which do not recruit). Numbers of age classes were chosen following conclusions from goodness-of-fit tests (see above; Online Appendix S3), prior analyses [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF]) and findings in larids of similar size (Table 1). We first assumed equal detection for pre-breeders and breeders (age-dependent temporary emigration accounts for the absence of yearlings from the study area-often observed in larids; e.g., [START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF][START_REF] Szostek | Immigrants are attracted by local pre-breeders and recruits in a seabird colony[END_REF]. We tested for different detection probabilities in pre-breeders and breeders over a subset of best models (Online Appendix S4), because they could have differences in colony attendance inducing differences in detection. When analyzing the reduced data set (sexed individuals), we compared multiple models and considered additive or multiplicative effects of sex on biologically relevant groupings of age classes (Online Appendix S4).

Results

All AICc values and comparisons are given in Online Appendix S4. Parameter estimates from the best models in each selection step are given in Online Appendix S5, S6. Time-varying models indicated strong temporal variations in survival and movement, but not in recruitment probability. However, they provided the same conclusions on age-and sex-dependence. For clarity, we thus only present results from time-constant models (see Online Appendix S5 for time-varying models). Parameter estimates are given with 95% confidence intervals ('95% CI').

Complete data set (sexed and unsexed individuals)

The best model without time variation (Model 1, Table 2) had two age classes for survival, four for dispersal, and three for recruitment. This model had AICc lower by 183.7 compared to the model with the minimum numbers of age classes (two age classes for survival and dispersal, one for recruitment: see "Materials and methods"; Model 101, Online Appendix S4: Table S1). Detection was independent of breeding status.

Dispersal propensity decreased with age, and breeders (i.e., already recruited in the study area) were much more philopatric than pre-breeders. The emigration probability of pre-breeders was very high at age 1 but then decreased until age 3 (Fig. 3a). Pre-breeder immigration probability was low and continuously decreased from age 2 to 4 and older (Fig. 3b). Accordingly, pre-breeders present in the area but not recruiting at age 3 were very likely to leave and came back only in small numbers sometimes many years after their emigration. For pre-breeders that survived, the probability of being inside the study area (see Online Appendix S7) increased from 0.13 to 0.39 from age 2 to 4, and then fell close to zero for older individuals (Fig. 3c). The emigration rate of breeders was lower than their immigration rate (Fig. 3a,b). For breeders that survived, the probability of being inside the study area decreased with age, from 0.95 the year after recruitment to 0.79 several years afterwards (Fig. 3c).

The bulk of recruitment ranged over 2-3 (mostly 3) years old (Fig. 3d). A quarter of pre-breeders alive and present in the study area at age 2 recruited at that age; this recruitment rate was much higher (ca. 0.9) at age 3, and similar at age 4 and older (Fig. 3d). These rates are conditional on being alive and inside the study area (Fig. 2): they must be integrated with dispersal to properly figure recruitment of locally born individuals (see Online Appendix S7). Given temporary emigration, the probability of being alive and recruiting in the natal area was 0.05 at age 2, 0.18 at age 3, falling to 0.004 at age 4 and continuing to decrease afterward (Fig. 3d).

First-year survival probability was higher than what is commonly found in larids of similar size (Table 1), but the estimate was fairly imprecise [0.77 (0.30,0.96)]. Two complementary models in which we fixed first-year survival at 0.5 or 0.95 slightly modified pre-breeder dispersal probabilities (Online Appendix S6: Table S8), but other parameters were not impacted, so that our conclusions on age-dependent dispersal and recruitment remained unchanged. Detection was very high [0.86 (0.83,0.88)] and assignment probabilities were consistent regarding the observer's ability to assess breeding status (see Online Appendix S8).

A1,≥ 2 A[1,2],≥ 3 A1,2,≥ 3 A1,≥ 2 A1,≥ 2 A1,≥ 2 A1,≥ 2 A1,≥ 2 A1,≥ 2 E × A1,2,3,≥ 4 E × A1,2,3,≥ 4 E × A1,2,3,≥ 4 E ×A1,2,3,≥ 4 E × A1,2,3,≥ 4 E × A1,2,3,≥ 4 E × (A1,2,3,≥ 4 + S) E × (A1,2,3,≥ 4 + S) E × (A1,2,3,≥ 4 + S) E × (A1,2,3,≥ 4 + S) E × (A1,2,3,≥ 4 + S)

Reduced data set (sexed individuals)

In the time-constant model applied to the reduced data set (Model 6, Table 2), estimates were very similar to what was previously obtained (Model 1), with larger confidence inter-vals (Online Appendix S6: Table S7). First-year survival probability was very poorly estimated [0.997 (0,1)]. In a complementary model with the first-year survival fixed at 0.77 (value from Model 1), estimates were even more similar to Model 1 (Online Appendix S6: Table S8).

Males recruited later and dispersed slightly more than females (Model 6 vs. Model 7, AICc difference: 9.49, Table 2). The best models showed no sex bias in survival. There was a sex difference in movement probability, which was irrespective of movement direction [emigration or immigration; estimate of the difference had 95% CI excluding zero: 0.19 (0.02, 0.36) on the logit scale]. Movement probability was slightly higher for males [e.g., pre-breeder emigration at age 1 was 0.88 (0.86, 0.89) for males and 0.85 (0.83, 0.87) for females; Online Appendix S6]. There was also a sex difference in recruitment probability at age 2 and 3 [estimate of the difference had 95% CI excluding zero: 0.88 (0.27, 1.50) on the logit scale]. Local recruitment probability was higher for males [at age 2: 0.31 (0.22, 0.42), at age 3: 0.92 (0.84, 0.96)] than for females [at age 2: 0.16 (0.10, 0.25), at age 3: 0.83 (0.72, 0.90)]. S7), from which probabilities of being in the study area were derived (Online Appendix S7)

Discussion

Because the slender-billed gull is socially and seasonally monogamous, and nomadically breeding, we suggested that the lack of breeding site tenacity and year-to-year territory ownership might induce no difference in dispersal according to age or sex (H1), and a limited delay in recruitment age (H2) with females recruiting later than males (H3). Our results are in accordance with these predictions: (H2) recruitment presented low delay and (H3) males recruited earlier than females. In contrast (with H1), we found that temporary emigration was higher in pre-breeders than in breeders and decreased with age, and males had a slightly higher tendency to disperse outside the study area than females. These results suggest that other mechanisms than those associated with competition for holding a breeding territory over the years shape betweenindividual variations in dispersal and recruitment.

Variability in recruitment age

Age at first reproduction is commonly quite variable in long-lived species occupying relatively stable habitats. In these species, few individuals recruit early and recruitment is spread over several age classes (e.g., [START_REF] Becker | The role of intrinsic factors for the recruitment process in long-lived birds[END_REF][START_REF] Kim | Effects of recruiting age on senescence, lifespan and lifetime reproductive success in a long-lived seabird[END_REF][START_REF] Martin | Determinants and consequences of age of primiparity in bighorn ewes[END_REF][START_REF] Desprez | Age-specific cost of first reproduction in female southern elephant seals[END_REF]. In colonial larids that have about the same size and lifespan as the slender-billed gull, reproduction can begin at age 2, but most recruitment occurs at age 3-6 and may spread even later (Table 1). In the slenderbilled gull, recruitment in the natal area occurs earlier and shows a much narrower spread over age classes (very few recruitment at age 2, most at age 3, and almost no at older ages).

In relatively stable habitats, year-to-year colony-site tenacity strengthens the importance of nest-site differences, which implies prospecting, contesting, and eventually queuing for good-quality habitats; a competitive process that may expand over several years [START_REF] Becker | The role of intrinsic factors for the recruitment process in long-lived birds[END_REF][START_REF] Van De Pol | Variation in habitat choice and delayed reproduction: adaptive queuing strategies or individual quality differences?[END_REF][START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF]). Nomadic breeders are not constrained by such long-standing competition, which may explain the lower recruitment delays in slender-billed gulls (compared to other species, Table 1). Alternatively, the apparent larger recruitment delays in species in stable habitats might result from the relatively small spatial scale of most studies (one or a few close colonies), whereas we studied recruitment at a regional scale spanning over several hundred kilometres. For instance, in a metapopulation of black-headed gulls, recruitment in the largest colony (probably saturated but of high quality) occurred later (age 2-5) than in smaller colonies (probably less competitive but of lower quality: age 2-4; [START_REF] Grosbois | La dispersion: trait d'histoire de vie et paramètre démographique: étude empirique dans une population de mouette rieuse[END_REF]. Accordingly, if one ignores small patches and focuses only on large, saturated patches where competition for territories is stronger, recruitment age is likely to be overestimated.

A decrease in breeding density may thus enhance accessibility to breeding sites, therefore, anticipating recruitment (see, e.g., [START_REF] Crespin | Recruitment to a seabird population depends on environmental factors and on population size[END_REF]. Density dependence is unlikely to operate in the slender-billed gull in our study area: observations do not suggest that nesting space is limiting in the colony sites, and breeding pairs on a colony site are usually 100-300 (maximum observed: 722) which is low compared to ca. 6000 pairs in Sfax, Tunisia [START_REF] Sanz-Aguilar | Living on the edge: demography of the slender-billed gull in the western mediterranean[END_REF]. The absence of year-to-year territory ownership and the low heterogeneity in nest-site quality within the colony clearly relax the competition for nest sites. This is also suggested by the low levels of aggression in crèching larids inhabiting unstable habitats compared with non crèching larids in relatively stable habitats [START_REF] Besnard | First quantitative comparison of aggression between crèching and non-crèching larid species[END_REF]). The remaining variability in recruitment age which we detected might stem from slight individual differences in behavioural maturation (e.g., gain in competitive and foraging skills), mating, and synchronization with the group [START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF]), which can be expected in most animal taxa [START_REF] Charlesworth | Evolution in age-structured populations[END_REF].

Moreover, we modelled recruitment only inside the study area in locally born individuals. It is, however, likely that part of recruitment occurs outside this area, so that actual recruitment might be even less delayed than what our results indicate. This would be in line with findings in the Audouin's gull (Ichthyaetus audouinü), another larid thought to have evolved in unstable habitats. In this species, [START_REF] Oro | Comparing demographic parameters for philopatric and immigrant individuals in a longlived bird adapted to unstable habitats[END_REF] showed no difference in recruitment rates between immigrants and native individuals in the largest colony. Similarly, recruitment rates of slender-billed gulls might be identical in the natal or immigration area.

Breeding status and age-dependence in dispersal

Yearlings were very likely to be outside the study area, corroborating the fact that immature larids are usually absent from the breeding grounds (e.g., [START_REF] Aubry | Habitat selection, age-specific recruitment and reproductive success in a long-lived seabird[END_REF][START_REF] Szostek | Immigrants are attracted by local pre-breeders and recruits in a seabird colony[END_REF]). In addition, and even when excluding yearlings, temporary emigration was lower in breeders than in pre-breeders at the regional scale modelled here (Fig. 3). Breeder emigration was higher at age 3 than at age 4 and older (although this was unclear in time-constant models, it was confirmed by time-varying models; Fig. 3, Online Appendix S5). Overall, breeders were much more regionally philopatric than we expected, though they were not philopatric to the colony site. Nevertheless, permanent emigration is strongly suspected in slender-billed gulls because of the low local survival estimates [START_REF] Doxa | Inferring dispersal dynamics from local population demographic modelling: the case of the slender-billed gull in France[END_REF]; and see Table 1). Such an increase in philopatry with age or experience is a usual pattern in non-nomadic larids of similar size (at the colony scale: Table 1), as well as in many animals, and can be explained by increased competitive abilities which ease territory acquisition and maintenance [START_REF] Bowler | Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics[END_REF]. Even when a habitat is unstable at the local scale, older individuals may benefit from spatial knowledge of potential foraging and breeding zones that do not radically change over the years at the regional scale (e.g., [START_REF] Bradshaw | Loyalty pays: potential life history consequences of fidelity to marine foraging regions by southern elephant seals[END_REF][START_REF] Wakefield | Long-term individual foraging site fidelity-why some gannets don't change their spots[END_REF], which should favour a decrease in dispersal propensity with age. Here, this idea is also supported by the clear tendency of slender-billed gulls to use the same wetland complex in the Camargue over the years (Fig. 1).

Sex bias in dispersal

The animal literature have suggested that kin competition and inbreeding risk weakly explain which sex disperses the most (and they may be avoided through kin recognition), but territoriality has remained a major explanatory factor [START_REF] Trochet | Evolution of sexbiased dispersal[END_REF]. In bird species inhabiting relatively stable environments (or at least non-nomadic breeders), males usually disperse less than females (see, e.g., in larids: Table 1), because breeding habitat predictability provide them with benefits in holding the same territory over the years [START_REF] Greenwood | The natal and breeding dispersal of birds[END_REF]. In contrast, our results suggest that slender-billed gull males moved in and out of the study area slightly more often than did females. Even if the difference was small as expected, it was significant and deserves attention.

Interestingly, in slender-billed gull fledglings, the sex ratio at ringing was slightly imbalanced [46% females out of 2392 sexed individuals (X² = 14.32, P < 0.001) over the study period, with the same trend in most years: Online Appendix S9]. As we detected no sex effect on survival, this bias should persist in all age classes. In most animal taxa, lower availability of females is expected to strengthen male-male competition for mating [START_REF] Jirotkul | Operational sex ratio influences female preference and male-male competition in guppies[END_REF], thus promoting female choosiness [START_REF] Berglund | The operational sex ratio influences choosiness in a pipefish[END_REF], a behaviour known to favour male dispersal [START_REF] Kokko | Lonely hearts or sex in the city? Density-dependent effects in mating systems[END_REF]. In addition, higher regional philopatry could offer females a familiarity advantage [START_REF] Piper | Making habitat selection more "familiar": a review[END_REF] in acquiring feeding experience in the area (e.g., [START_REF] Bradshaw | Loyalty pays: potential life history consequences of fidelity to marine foraging regions by southern elephant seals[END_REF], especially in regard to investment in egg laying [START_REF] Williams | Mechanisms underlying the costs of egg produc tion[END_REF]; and see below). More generally in animal taxa, a similar reasoning could be applied to explain sex-biased dispersal, based on asymmetry in the costs induced by parental investment or even secondary sexual traits [START_REF] Trochet | Evolution of sexbiased dispersal[END_REF].

Sex bias in recruitment

We predicted later female recruitment due to costs of egg laying which would not be (over)compensated by costs of holding a breeding territory over the years for males. In non nomadic larids having a similar size as the slender-billed gull, both male and female biases have been reported in recruitment age (Table 1). Although rarely documented in the animal literature, sexbiased recruitment has been suggested to result from unbalanced sex ratio, as the surplus of one sex strengthens intrasexual competition and reduces access to reproduction [START_REF] Mills | The influence of age and pair-bond on the breeding biology of the red-billed gull Larus novaehollandiae scopulinus[END_REF][START_REF] Becker | The role of intrinsic factors for the recruitment process in long-lived birds[END_REF]. However, slender-billed gull males recruited earlier than the outnumbered females, so that competition for mating cannot drive sex-dependence in recruitment in this case. In many birds, including larids, laying date gets earlier with age and is negatively correlated with breeding success (Forslund and Pürt 1995;[START_REF] Arnold | Seasonal declines in reproductive success of the common tern Sterna hirundo: timing or parental quality?[END_REF]). This may stem from experience-driven improvements in performance (Bos-man et al. 2013). In slender-billed gulls, egg laying is highly synchronous, taking place within less than 15 days [START_REF] Besnard | Evolution de l'élevage des poussins en crèche chez les laridés[END_REF]. Such synchronization is explained by crèching behaviour: late-born chicks are unable to join the crèche when it leaves the colony site and consequently die [START_REF] Besnard | Evolution de l'élevage des poussins en crèche chez les laridés[END_REF]. This context of asymmetry in reproductive costs suggests that unsynchronized young females (that lay too late) may be prone to delaying recruitment to ensure chick survival through synchronous laying with older, experienced individuals. More generally in animal taxa, asymmetry in reproductive costs [START_REF] Th | The evolution of parental care[END_REF] should not be neglected among the forces that are likely to produce sex differences in recruitment patterns.

Conclusion

Our study invites to revisit recruitment and dispersal paradigms in long-lived species that were mostly elaborated from the study of species incurring territorial costs associated with year-to-year territory maintenance and notably facing competition resulting from density-dependence. Here, we showed that a nomadically breeding bird species with absence of year-to-year territory holding exhibited a few differences in dispersal between sexes and had almost no delay and variation in recruitment age. Nonetheless, remaining variations in recruitment age and state-dependent dispersal (here, a delay in female recruitment, a slight male-biased dispersal, and increased dispersal with age) suggest the role of other ecological processes such as sex ratio imbalance, asymmetric costs of reproduction, and benefits of regional familiarity.

Figure

  Figure 1Locations of slender-billed gull colonies in France over 1997-2012. Panel b is a zoom of the box in panel a: the Camargue wetlands. Shaded zones: marshes, white zone: Mediterranean Sea, squares: main cities. Colony sites (circles) are labelled with years of occupation. Scaling made several sites undistinguishable, which explains why less than 45 sites appear here and why the same year sometimes appears more than once next to a point

Figure 2

 2 Figure 2 Diagram of fates from one breeding season (t) to the next (t + 1). Grey boxes: unobservable states (dead or outside the study area); white boxes: observable states (inside the area). Dotted arrows: (portions of) paths leading to absence of resighting; filled arrows: paths leading to assignment of a category of assessed breeding status. Arrow subscripts specify the associated probability (if none, probability is 1): survival rate (ϕ), emigration rate (Sio), immigration rate (Soi), recruitment rate (r), detection probability (p), assignment probability (ae, with 'e' the observation event). Newborns are only observed as 'certain non-breeder'; older individuals are no longer observed as such. Pre-breeders cannot be observed as 'certain breeder' (they have no behaviour relatable to breeding with certainty.

Figure 3

 3 Figure 3 Age-dependent a emigration, b immigration, c presence in the study area, and d recruitment. Circles: pre-breeders; squares: breeders. Individual histories start at birth in the study area: pre-breeder emigration occurs only from age 1, prebreeder immigration from age 4. In panel c, 'k': age 0 for pre-breeders and recruitment age for breeders. In panel d, filled circles: recruitment rate conditional on being alive in the study are (i.e., parameter in the model), open circles: recruitment rate for any locally born individual (not conditional on being alive in the area), line: proportion of new recruits among alive breeders (in or out the study area). Segments indicate 95% confidence intervals. Parameter estimates are from Model 1 (Online Appendix S6: TableS7), from which probabilities of being in the study area were derived (Online Appendix S7)

Table 2

 2 Summary of time-constant model selection

	Data	Step	Covariates included	Model Parameter variation		K	ΔAICc	WAICc
					9 5	S	r	p
	I	i	Age	1	A1,≥ 2 A1,≥
				2	2
				3
				4
				5
	II	ii	Age	6
		iii	Age, sex	7
				8
				9
				10
				11

  Only the five best models in each selection step are given. This summary indicates how survival (q5), movement (S), local recruitment (r), and detection (p) probabilities vary with the covariates considered (A age; S sex) and individual states (E pre-breeder inside the area, pre-breeder outside the area, breeder inside the area and breeder outside the area). '.' indicates no variation. With the complete data set (I), 73 models were compared (step i). With the reduced data set (II, only sexed individuals), 40 models were compared: we first (step ii) fitted the best age-dependent structure selected in step i (Model 1), then (step iii) selected the best sex-dependent model. '×' designates interactions, '+' designates additive effects. Subscripts specify age-class divisions and combinations. K is the number of parameters, ΔAICc is the difference in corrected Akaike Information Criterion to the best model for each data set, wAICc is the corresponding AICc weights. Parameter estimates from model 1, 6, and 7 are given in Online Appendix S6: Table7

	A2,3,≥	4	.	19	0	0.23
	A2,3,4,≥ . 5		20	1.32	0.12
	A2,3,≥ 4	E		20	1.43	0.11
	A2,3,≥ 4	.		19	1.78	0.10
	A2,3,≥ 4	.		20	1.99	0.09
	A2,3,≥ 4	.		19	9.49	0
	A2,3,≥ 4 + A[2:3] × S A2,3 × S + A≥ 4	. .	21 22	0 1.66	0.39 0.17
	A2,3,≥ 4 + S	.	21	2.57	0.11
	A2,3,≥ 4 × S	.	23	3.05	0.08
	A2,≥ 4 + A3 × S	.	21	3.61	0.06

Acknowledgements

We are grateful to the many volunteers, ring-ers, and students who assisted with captures and observations at the colonies, and in particular to Christophe Pin who has been instrumental in maintaining the ring-resighting effort on the long-term. We are also grateful to Roger Pradel for his useful advice about E-SURGE and multievent modelling. The monitoring of the slender-billed gull was funded by Tour du Valat, the non-profit organisation Les Amis du Marais du Vigueirat, and the MAVA foundation. This work was supported by the French Laboratory of Excellence project 'TULIP' (ANR-10-LABX-41; ANR-11-IDEX-0002-02).

Author contribution statement PA, CF, and A Besnard formulated the ideas; PA and CF performed the analyses and wrote the manuscript; NS conceived the monitoring study. NS and A Béchet were responsible for data collection; ASP performed genetic sexing; A Besnard, A Béchet, CML, and NS provided editorial advice. PA and CF have contributed equally to the work.