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Convoy

A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used in a non-military sense, for example when driving through remote areas.

Age of Sail
Naval convoys have been in use for centuries, with examples of merchant ships traveling under naval protection dating to the 12th century. The use of organized naval convoys dates from when ships began to be separated into specialist classes and national navies were established.

By the French Revolutionary Wars of the late 18th century, effective naval convoy tactics had been developed to ward off pirates and privateers. Some convoys contained several hundred merchant ships. The most enduring system of convoys were the Spanish treasure fleets, that sailed from the 1520s until 1790.

When merchant ships sailed independently, a privateer could cruise a shipping lane and capture ships as they passed. Ships sailing in convoy presented a much smaller target: a convoy was as hard to find as a single ship. Even if the privateer found a convoy and the wind was favourable for an attack, it could still hope to capture only a handful of ships before the rest managed to escape, and a small escort of warships could easily thwart it. As a result of the convoy system's effectiveness, wartime insurance premiums were consistently lower for ships that sailed in convoys.

Many naval battles in the Age of Sail were fought around convoys, including:
 * The Battle of Portland (1653)
 * The Battle of Ushant (1781)
 * The Battle of Dogger Bank (1781)
 * The Glorious First of June (1794)
 * The Battle of Pulo Aura (1804)

By the end of the Napoleonic Wars, the Royal Navy had in place a sophisticated convoy system to protect merchant ships. Losses of ships travelling out of convoy, however, were so high that no merchant ship was allowed to sail unescorted.

World War I
In the early 20th century, the dreadnought changed the balance of power in convoy battles. Steaming faster than merchant ships and firing at long ranges, a single battleship could destroy many ships in a convoy before the others could scatter over the horizon. To protect a convoy against a capital ship required providing it with an escort of another capital ship, at very high opportunity cost (i.e. potentially tying down multiple capital ships to defend different convoys against one opponent ship).

Battleships were the main reason that the British Admiralty did not adopt convoy tactics at the start of the first Battle of the Atlantic in World War I. But the German capital ships had been bottled up in the North Sea, and the main threat to shipping came from U-boats. From a tactical point of view, World War I–era submarines were similar to privateers in the age of sail. These submarines were only a little faster than the merchant ships they were attacking, and capable of sinking only a small number of vessels in a convoy because of their limited supply of torpedoes and shells. The Admiralty took a long time to respond to this change in the tactical position, and in April 1917 convoys were trialled, before being officially introduced in the Atlantic in September 1917.

Other arguments against convoys were raised. The primary issue was the loss of productivity, as merchant shipping in convoy has to travel at the speed of the slowest vessel in the convoy and spent a considerable amount of time in ports waiting for the next convoy to depart. Further, large convoys were thought to overload port resources.

Actual analysis of shipping losses in World War I disproved all these arguments, at least so far as they applied to transatlantic and other long-distance traffic. Ships sailing in convoys were far less likely to be sunk, even when not provided with an escort. The loss of productivity due to convoy delays was small compared with the loss of productivity due to ships being sunk. Ports could deal more easily with convoys because they tended to arrive on schedule and so loading and unloading could be planned.

In his book On the Psychology of Military Incompetence, Norman Dixon suggested that the hostility towards convoys in the naval establishment were in part caused by a (sub-conscious) perception of convoys as effeminating, due to warships having to care for civilian merchant ships. Convoy duty also exposes the escorting warships to the sometimes hazardous conditions of the North Atlantic, with only rare occurrences of visible achievement (i.e. fending off a submarine assault).

Atlantic
The British adopted a convoy system, initially voluntary and later compulsory for almost all merchant ships, the moment that World War II was declared. Each convoy consisted of between 30 and 70 mostly unarmed merchant ships. Canadian, and later American, supplies were vital for Britain to continue its war effort. The course of the Battle of the Atlantic was a long struggle as the Germans developed anti-convoy tactics and the British developed counter-tactics to thwart the Germans.

The capability of a heavily armed warship against a convoy was dramatically illustrated by the fate of Convoy HX 84. On November 5, 1940, the German heavy cruiser GERMAN CRUISER Admiral Scheer encountered the convoy. Maiden, Trewellard, and Kenbame Head were quickly destroyed, and Beaverford and Fresno City falling afterwards. Only the sacrifices of the armed merchant cruiser HMS Jervis Bay (F40) and the freighter Beaverford to stall the Scheer, in addition to failing light, allowed the rest of the convoy to escape.

The deterrence value of a battleship in protecting a convoy was also dramatically illustrated when the German light battleships (referred by some as battlecruisers) GERMAN BATTLESHIP Scharnhorst and GERMAN BATTLESHIP Gneisenau, mounting 11 in guns, came upon an eastbound British convoy (HX 106, with 41 ships) in the North Atlantic on February 8, 1941. When the Germans detected the slow but well-protected battleship HMS Ramillies (07) escorting the convoy, they fled the scene rather than risk damage from her 15 in guns.

The enormous number of vessels involved and the frequency of engagements meant that statistical techniques could be applied to evaluate tactics: an early use of operational research in war.

Prior to overt participation in World War II, the US was actively engaged in convoys with the British in the North Atlantic Ocean, primarily supporting British activities in Iceland.

After Germany declared war on the US, the US Navy decided not to organize convoys on the American eastern seaboard. US Fleet Admiral Ernest King ignored advice on this subject from the British, as he had formed a poor opinion of the Royal Navy early in his career. The result was what the U-boat crews called their Second Happy Time, which did not end until convoys were introduced.

Pacific
In the Pacific Theater of World War II, Japanese merchant ships rarely traveled in convoys. Japanese destroyers were generally deficient in antisubmarine weaponry compared to their Allied counterparts, and the Japanese navy did not develop an inexpensive convoy escort like the Allies' destroyer escort/frigate until it was too late. In the early part of the conflict, American submarines in the Pacific were ineffective as they suffered from timid tactics, faulty torpedoes, and poor deployment, while there were only small numbers of British and Dutch boats. U.S. Admiral Charles A. Lockwood's efforts, coupled with strenuous complaints from his captains, rectified these problems and U.S. submarines became much more successful by war's end. As a result, the Japanese merchant fleet was largely destroyed by the end of the war. Japanese submarines, unlike their U.S. and German equivalents, focused on U.S. battle fleets rather than merchant convoys, and while they did manage some early successes, sinking two U.S. carriers, they failed to significantly inhibit the invasion convoys carrying troops and equipment in support of the U.S. island-hopping campaign.

Several notable battles in the South Pacific involved Allied bombers interdicting Japanese troopship convoys which were often defended by Japanese fighters, notable Guadalcanal (13 November 1942), Rabaul (5 January 1943), and the Battle of the Bismarck Sea (2–4 March 1943).

At the Battle off Samar, the effectiveness of the U.S. Navy's escorts was demonstrated when they managed to defend their troop convoy from a much larger and more powerful Japanese battle-fleet. The Japanese force comprised four battleships and numerous heavy cruisers, while the U.S. force consisted of escort carriers, destroyers, and destroyer escorts. Large numbers of American aircraft (albeit without much anti-ship ordnance other than torpedoes) and aggressive tactics of the destroyers (with their radar-directed gunfire) allowed the U.S. to sink three Japanese heavy cruisers at the cost of one escort carrier and three destroyers.

Tactics
The German anti-convoy tactics included:
 * long-range surveillance aircraft to find convoys;
 * strings of U-boats (wolfpacks) that could be directed onto a convoy by radio;
 * breaking the British naval codes;
 * improved anti-ship weapons, including magnetic detonators and sonic homing torpedoes.

The Allied responses included:
 * air raids on the U-boat bases at Brest and La Rochelle;
 * converted merchant ships, e.g., Merchant aircraft carriers, Catapult Aircraft Merchantman and armed merchant cruisers
 * Q-ships, submarine-hunters disguised as unarmed merchant ships to lure submarines into an attack
 * more convoy escorts, including cheaply produced yet effective destroyer escorts/frigates (as corvettes were meant as a stopgap), and escort carriers;
 * fighter aircraft (carried by escort carriers and merchant aircraft carriers) that would drive off German bombers and attack U-boats
 * long-range aircraft patrols to find and attack U-boats;
 * improved anti-submarine weapons such as the hedgehog;
 * larger convoys, allowing more escorts per convoy as well as the extraction of enough escorts to form hunter-killer support groups that were not attached to a particular convoy
 * allocating vessels to convoys according to speed, so that faster ships were less exposed.

They were also aided by
 * improved sonar (ASDIC) allowing escort vessels to better track U-boats;
 * breaking the German naval cipher;
 * improved radar and radio direction finding allowing planes to find and destroy U-boats;
 * improved escort anti-submarine tactics developed by the Western Approaches Tactical Unit

Convoy battles
Many naval battles of World War II were fought around convoys, including:
 * Convoy PQ 16, May 1942
 * Convoy PQ 17, June–July 1942
 * Convoy PQ 18, September 1942
 * Operation Pedestal, August 1942
 * The Naval Battle of Guadalcanal, November 1942
 * The Battle of the Barents Sea, December 1942
 * The Battle of the Bismarck Sea, March 1943

The convoy prefix indicates the route of the convoy. For example, 'PQ' would be Iceland to Northern Russia and 'QP' the return route.

Analysis
The success of convoys as an anti-submarine tactic during the world wars can be ascribed to several reasons related to U-boat capabilities, the size of the ocean and convoy escorts.

In practice, Type VII and Type IX U-boats were limited in their capabilities. Submerged speed and endurance was limited and not suited for overhauling many ships. Even a surfaced U-boat could take several hours to gain an attack position. Torpedo capacity was also restricted to around fourteen (Type VII) or 24 (Type IX), thus limiting the number of attacks that could be made, particularly when multiple firings were necessary for a single target. There was a real problem for the U-boats and their adversaries in finding each other; with a tiny proportion of the ocean in sight, without intelligence or radar, warships and even aircraft would be fortunate in coming across a submarine. The Royal Navy and later the United States Navy each took time to learn this lesson. Conversely, a U-boat's radius of vision was even smaller and had to be supplemented by regular long-range reconnaissance flights.

For both major allied navies, it had been difficult to grasp that, however large a convoy, its "footprint" (the area within which it could be spotted) was far smaller than if the individual ships had traveled independently. In other words, a submarine had less chance of finding a single convoy than if it were scattered as single ships. Moreover, once an attack had been made, the submarine would need to regain an attack position on the convoy. If, however, an attack were thwarted by escorts, even if the submarine had escaped damage, it would have to remain submerged for its own safety and might only recover its position after many hours' hard work. U-boats patrolling areas with constant and predictable flows of sea traffic, such as the United States Atlantic coast in early 1942, could dismiss a missed opportunity in the certain knowledge that another would soon present itself.

The destruction of submarines required their discovery, an improbable occurrence on aggressive patrols, by chance alone. Convoys, however, presented irresistible targets and could not be ignored. For this reason, the U-boats presented themselves as targets to the escorts with increasing possibility of destruction. In this way, the Ubootwaffe suffered severe losses, for little gain, when pressing pack attacks on well-defended convoys.

Post-World War II

The largest convoy effort since World War II was Operation Earnest Will, the U.S. Navy's 1987–88 escort of reflagged Kuwaiti tankers in the Persian Gulf during the Iran–Iraq War.

In the present day, convoys are used as a tactic by navies to deter pirates off the coast of Somalia from capturing unarmed civilian freighters who would otherwise pose easy targets if they sailed alone.

Humanitarian aid convoys
The word "convoy" is also associated with groups of road vehicles being driven, mostly by volunteers, to deliver humanitarian aid, supplies, and—a stated objective in some cases—"solidarity".

In the 1990s these convoys became common traveling from Western Europe to countries of the former Yugoslavia, in particular Bosnia and Kosovo, to deal with the aftermath of the wars there. They also travel to countries where standards of care in institutions such as orphanages are considered low by Western European standards, such as Romania; and where other disasters have led to problems, such as around the Chernobyl disaster in Belarus and Ukraine.

The convoys are made possible partly by the relatively small geographic distances between the stable and affluent countries of Western Europe, and the areas of need in Eastern Europe and, in a few cases, North Africa and even Iraq. They are often justified because although less directly cost-effective than mass freight transport, they emphasise the support of large numbers of small groups, and are quite distinct from multinational organisations such as United Nations humanitarian efforts.

Truckers' convoys
Truckers' convoys consisting of semi-trailer trucks and/or petrol tankers are more similar to a caravan than a military convoy.

Truckers' convoys were created as a byproduct of the U.S.' national 55 mph speed limit and 18-wheelers becoming the prime targets of speed traps. Most truckers had difficult schedules to keep and as a result had to maintain a speed above the posted speed limit to reach their destinations on time. Convoys were started so that multiple trucks could run together at a high speed with the rationale being that if they passed a speed trap the police would only be able to pull over one of the trucks in the convoy. When driving on a highway, convoys are also useful to conserve fuel by drafting.

The film Convoy, inspired by a 1975 song of the same name, explores the camaraderie between truck drivers, where the culture of the CB radio encourages truck drivers to travel in convoys.

Truck convoys are sometimes organized for fundraising, charity, or promotional purposes. They can also be used as a form of protest, such as the Canada convoy protest in 2022.

Special convoy rights
The Highway Code of several European countries (Norway, Italy, Greece, Netherlands, Germany, Austria, Switzerland, possibly more) includes special rights for marked convoys. They have to be treated like a single vehicle. If the first vehicle has passed an intersection, all others may do so without interruption. If other road users overtake the convoy, they are not allowed to split into the queue. Clear and uniform marking has been required in court decisions for these rights to apply. Operating such convoy usually needs special permission, but there are exemptions for emergency and catastrophe intervention. Common practice is, to operate with the same style of marking as NATO convoys: STANAG 2154 marking plus country-specific augmentation listed in Annex B to the STANAG.

During the Cold War with its high number of military exercises, the military was the main user of convoy rights. Today, catastrophes like large-scale flooding might bring a high number of flagged convoys to the roads. Large-scale evacuations for the disarming of World War II bombs are another common reason for non-governmental organization (NGO) unit movements under convoy rights.

Storm convoys
In Norway, "convoy driving" (kolonnekjøring) is used during winter in case weather is too bad for vehicles to pass on their own. Convoy driving is initiated when the strong wind quickly fills the road with snow behind snowplows, particularly on mountain passes. Only a limited number of vehicles are allowed for each convoy and convoy leader is obliged to decline vehicles not fit for the drive. Storm convoys are prone to multiple-vehicle collision. Convoy driving is used through Hardangervidda pass on road 7 during blizzards. Convoy is sometimes used on road E134 at the highest and most exposed sections during bad weather. On European route E6 through Saltfjellet pass convoy driving is often used when wind speed is over 15–20 m/s (fresh or strong gale) in winter conditions. During the winter of 1990 there was convoy driving for almost 500 hours at Saltfjellet

World War II

 * Edwards, Bernard. The road to Russia: Arctic convoys 1942 (Leo Cooper Books, 2002)
 * Forczyk, Robert. Fw 200 Condor Vs Atlantic Convoy, 1941–1943 (Osprey Publishing, 2010)
 * Hague, Arnold. The allied convoy system, 1939–1945: its Organization, Defence and Operation (Naval Institute Press, 2000)
 * Kaplan, Philip, and Jack Currie. Convoy: merchant sailors at war, 1939–1945 (Aurum Press, 1998)
 * Middlebrook, Martin. Convoy: the Battle for Convoys SC. 122 and HX. 229 (Allen Lane, 1976)
 * Milner, Marc. "Convoy Escorts: Tactics, Technology and Innovation in the Royal Canadian Navy, 1939–1943." Military Affairs: The Journal of Military History, Including Theory and Technology (1984): 19–25.
 * O'Hara, Vincent P. In Passage Perilous: Malta and the Convoy Battles of June 1942 (Indiana University Press, 2012)
 * Smith, Peter Charles. Arctic Victory: The Story of Convoy PQ 18 (Kimber, 1975)
 * Winton, John. Convoy, The Defense of Sea Trade 1890–1990, 1983. ISBN 0-7181-2163-5

Official history

 * Commander in Chief, United States Fleet, "Convoy and Routing." Washington, 1945. 147 pp., online

title: Convoy


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Sugar glider

The sugar glider (Petaurus breviceps) is a small, omnivorous, arboreal, and nocturnal gliding possum. The common name refers to its predilection for sugary foods such as sap and nectar and its ability to glide through the air, much like a flying squirrel. They have very similar habits and appearance to the flying squirrel, despite not being closely related—an example of convergent evolution. The scientific name, Petaurus breviceps, translates from Latin as "short-headed rope-dancer", a reference to their canopy acrobatics.

The sugar glider is characterised by its pair of gliding membranes, known as patagia, which extend from its forelegs to its hindlegs. Gliding serves as an efficient means of reaching food and evading predators. The animal is covered in soft, pale grey to light brown fur which is countershaded, being lighter in colour on its underside. The sugar glider, as strictly defined in a recent analysis, is only native to a small portion of southeastern Australia, corresponding to southern Queensland and most of New South Wales east of the Great Dividing Range; the extended species group, including populations which may or may not belong to P. breviceps, occupies a larger range covering much of coastal eastern and northern Australia, New Guinea, and nearby islands. Members of Petaurus are popular exotic pets; these pet animals are also frequently referred to as "sugar gliders", but recent research indicates, at least for American pets, that they are not P. breviceps but a closely related species, ultimately originating from a single source near Sorong in West Papua. This would possibly make them members of the Krefft's glider (P. notatus), but the taxonomy of Papuan Petaurus populations is still poorly resolved.

Taxonomy and evolution
The genus Petaurus is believed to have originated in New Guinea during the mid Miocene epoch, approximately 18 to 24 million years ago. The modern Australian Petaurus, along with New Guinean members of what were formerly considered P. breviceps, diverged from their closest living New Guinean relatives ~9-12 mya. They probably dispersed from New Guinea to Australia between 4.8 and ~8.4 mya, with the oldest Petaurus fossils in Australia being dated to 4.46 million years. This may have been possible due to sea level lowering from about 7 to 10 mya, resulting in land bridges between New Guinea and Australia.

The taxonomy of the species is complex, and is still not fully resolved. It was formerly understood to have a wide range across Australia and New Guinea, being the only glider to have this distribution, and to be divided into seven subspecies, with three occurring in Australia and four in New Guinea. This traditional subspecific division was based on small morphological differences, such as colour and body size. However, a 2010 genetic analysis using mitochondrial DNA indicates that these morphologically-defined subspecies may not represent genetically unique populations.

Further studies have found significant genetic variation within populations traditionally classified in P. breviceps, sufficient to warrant splitting the species into multiple. The subspecies P. b. biacensis, from Biak Island off of New Guinea, was reclassified as a separate species, the Biak glider (Petaurus biacensis). In 2020, a landmark study suggested that P. breviceps actually comprised three cryptic species: the Krefft's glider (Petaurus notatus), found throughout most of eastern Australia and introduced to Tasmania, the savanna glider (Petaurus ariel), native to northern Australia, and a more narrowly defined P. breviceps, restricted to a small section of coastal forest in southern Queensland and most of New South Wales. In addition, other sugar glider populations throughout this range (such as those on New Guinea and the Cape York Peninsula) may represent undescribed species or be conspecific with previously described species. This indicates that contrary to previous findings of a large range (which in fact applied to P. notatus and, to a lesser extent, to P. ariel), P. breviceps is a range-restricted species that is sensitive to ecological disasters, such as the 2019-20 Australian bushfires, which significantly affected large portions of its habitat.

P. breviceps and P. notatus are estimated to have diverged ~1 million years ago, and may have originated from long term geographic isolation. The early-mid Pleistocene saw an uplifting of the Great Dividing Range, contributing to and coinciding with aridification of the interior of Australia, including on the western side of the range. This, as well as other climactic and geographic factors, may have isolated the ancestors of P. breviceps to refugia on the eastern, coastal side of the Great Dividing Range. This would be an example of allopatric speciation.

Distribution and habitat
Sugar gliders are distributed in the coastal forests of southeastern Queensland and most of New South Wales. Their distribution extends to altitudes of 2000m in the eastern ranges. In parts of its range, it may overlap with Krefft's glider (P. notatus).

The sugar glider occurs in sympatry with the squirrel glider and yellow-bellied glider; and their coexistence is permitted through niche partitioning where each species has different patterns of resource use.

Like all arboreal, nocturnal marsupials, sugar gliders are active at night, and they shelter during the day in tree hollows lined with leafy twigs. The average home range of sugar gliders is 0.5 ha, and is largely related to the abundance of food sources; density ranges from two to six individuals per hectare (0.8–2.4 per acre).

Native owls (Ninox sp.) are their primary predators; others in their range include kookaburras, goannas, snakes, and quolls. Feral cats (Felis catus) also represent a significant threat.

Appearance and anatomy
The sugar glider has a squirrel-like body with a long, partially (weakly) prehensile tail. The length from the nose to the tip of the tail is about 24 - 30 cm, and males and females weigh 140 and 115 g respectively. Heart rate range is 200–300 beats per minute, and respiratory rate is 16–40 breaths per minute. The sugar glider is a sexually dimorphic species, with males typically larger than females. Sexual dimorphism has likely evolved due to increased mate competition arising through social group structure; and is more pronounced in regions of higher latitude, where mate competition is greater due to increased food availability.

The fur coat on the sugar glider is thick, soft, and is usually blue-grey; although some have been known to be yellow, tan or (rarely) albino. A black stripe is seen from its nose to midway on its back. Its belly, throat, and chest are cream in colour. Males have four scent glands, located on the forehead, chest, and two paracloacal (associated with, but not part of the cloaca, which is the common opening for the intestinal, urinal and genital tracts) that are used for marking of group members and territory. Scent glands on the head and chest of males appear as bald spots. Females also have a paracloacal scent gland and a scent gland in the pouch, but do not have scent glands on the chest or forehead.

The sugar glider is nocturnal; its large eyes help it to see at night and its ears swivel to help locate prey in the dark. The eyes are set far apart, allowing more precise triangulation from launching to landing locations while gliding.

Each foot on the sugar glider has five digits, with an opposable toe on each hind foot. These opposable toes are clawless, and bend such that they can touch all the other digits, like a human thumb, allowing it to firmly grasp branches. The second and third digits of the hind foot are partially syndactylous (fused together), forming a grooming comb. The fourth digit of the forefoot is sharp and elongated, aiding in extraction of insects under the bark of trees.

The gliding membrane extends from the outside of the fifth digit of each forefoot to the first digit of each hind foot. When the legs are stretched out, this membrane allows the sugar glider to glide a considerable distance. The membrane is supported by well developed tibiocarpalis, humerodorsalis and tibioabdominalis muscles, and its movement is controlled by these supporting muscles in conjunction with trunk, limb and tail movement.

Lifespan in the wild is up to 9 years; is typically up to 12 years in captivity, and the maximum reported lifespan is 17.8 years.

Gliding
The sugar glider is one of a number of volplane (gliding) possums in Australia. It glides with the fore- and hind-limbs extended at right angles to the body, with feet flexed upwards. The animal launches itself from a tree, spreading its limbs to expose the gliding membranes. This creates an aerofoil enabling it to glide 50 m or more. For every 1.82 m travelled horizontally when gliding, it falls 1 m. Steering is controlled by moving limbs and adjusting the tension of the gliding membrane; for example, to turn left, the left forearm is lowered below the right.

This form of arboreal locomotion is typically used to travel from tree to tree; the species rarely descends to the ground. Gliding provides three dimensional avoidance of arboreal predators, and minimal contact with ground dwelling predators; as well as possible benefits in decreasing time and energy consumption spent foraging for nutrient poor foods that are irregularly distributed. Young carried in the pouch of females are protected from landing forces by the septum that separates them within the pouch.

Torpor
Sugar gliders can tolerate ambient air temperatures of up to 40 °C through behavioural strategies such as licking their coat and exposing the wet area, as well as drinking small quantities of water. In cold weather, sugar gliders will huddle together to avoid heat loss, and will enter torpor to conserve energy. Huddling as an energy conserving mechanism is not as efficient as torpor. Before entering torpor, a sugar glider will reduce activity and body temperature normally in order to lower energy expenditure and avoid torpor. With energetic constraints, the sugar glider will enter into daily torpor for 2–23 hours while in rest phase. Torpor differs from hibernation in that torpor is usually a short-term daily cycle. Entering torpor saves energy for the animal by allowing its body temperature to fall to a minimum of 10.4 °C to 19.6 °C. When food is scarce, as in winter, heat production is lowered in order to reduce energy expenditure. With low energy and heat production, it is important for the sugar glider to peak its body mass by fat content in the autumn (May/June) in order to survive the following cold season. In the wild, sugar gliders enter into daily torpor more often than sugar gliders in captivity. The use of torpor is most frequent during winter, likely in response to low ambient temperature, rainfall, and seasonal fluctuation in food sources.

Diet and nutrition
Sugar gliders are seasonally adaptive omnivores with a wide variety of foods in their diet, and mainly forage in the lower layers of the forest canopy. Sugar gliders may obtain up to half their daily water intake through drinking rainwater, with the remainder obtained through water held in its food. In summer they are primarily insectivorous, and in the winter when insects (and other arthropods) are scarce, they are mostly exudativorous (feeding on acacia gum, eucalyptus sap, manna, honeydew or lerp). Sugar gliders have an enlarged caecum to assist in digestion of complex carbohydrates obtained from gum and sap. To obtain sap or gum from plants, sugar gliders will strip the bark off trees or open bore holes with their teeth to access stored liquid. Little time is spent foraging for insects, as it is an energetically expensive process, and sugar gliders will wait until insects fly into their habitat, or stop to feed on flowers. Gliders consume approximately 11 g of dry food matter per day. This equates to roughly 8% and 9.5% of body weight for males and females, respectively.

They are opportunistic feeders and can be carnivorous, preying mostly on lizards and small birds. They eat many other foods when available, such as nectar, acacia seeds, bird eggs, pollen, fungi and native fruits. Pollen can make up a large portion of their diet, therefore sugar gliders are likely to be important pollinators of Banksia species.

Reproduction
Like most marsupials, female sugar gliders have two ovaries and two uteri; they are polyestrous, meaning they can go into heat several times a year. The female has a marsupium (pouch) in the middle of her abdomen to carry offspring. The pouch opens anteriorly, and two lateral pockets extend posteriorly when young are present. Four nipples are usually present in the pouch, although reports of individuals with two nipples have been recorded. Male sugar gliders have a bifurcated penis to correspond with the two uteri of females.

The age of sexual maturity in sugar gliders varies slightly between the males and females. Males reach maturity at 4 to 12 months of age, while females require from 8 to 12 months. In the wild, sugar gliders breed once or twice a year depending on the climate and habitat conditions, while they can breed multiple times a year in captivity as a result of consistent living conditions and proper diet.

A sugar glider female gives birth to one (19%) or two (81%) babies (joeys) per litter. The gestation period is 15 to 17 days, after which the tiny joey 0.2 g will crawl into a mother's pouch for further development. They are born largely undeveloped and furless, with only the sense of smell being developed. The mother has a scent gland in the external marsupium to attract the sightless joeys from the uterus. Joeys have a continuous arch of cartilage in their shoulder girdle which disappears soon after birth; this supports the forelimbs, assisting the climb into the pouch. Young are completely contained in the pouch for 60 days after birth, wherein mammae provide nourishment during the remainder of development. Eyes first open around 80 days after birth, and young will leave the nest around 110 days after birth. By the time young are weaned, the thermoregulatory system is developed, and in conjunction with a large body size and thicker fur, they are able to regulate their own body temperature.

Breeding is seasonal in southeast Australia, with young only born in winter and spring (June to November). Unlike animals that move along the ground, the sugar glider and other gliding species produce fewer, but heavier, offspring per litter. This allows female sugar gliders to retain the ability to glide when pregnant.

Socialisation
Sugar gliders are highly social animals. They live in family groups or colonies consisting of up to seven adults, plus the current season's young. Up to four age classes may exist within each group, although some sugar gliders are solitary, not belonging to a group. They engage in social grooming, which in addition to improving hygiene and health, helps bond the colony and establish group identity.

Within social communities, there are two codominant males who suppress subordinate males, but show no aggression towards each other. These co-dominant pairs are more related to each other than to subordinates within the group; and share food, nests, mates, and responsibility for scent marking of community members and territories.

Territory and members of the group are marked with saliva and a scent produced by separate glands on the forehead and chest of male gliders. Intruders who lack the appropriate scent marking are expelled violently. Rank is established through scent marking; and fighting does not occur within groups, but does occur when communities come into contact with each other. Within the colony, no fighting typically takes place beyond threatening behaviour. Each colony defends a territory of about 1 hectare where eucalyptus trees provide a staple food source.

Sugar gliders are one of the few species of mammals that exhibit male parental care. The oldest codominant male in a social community shows a high level of parental care, as he is the probable father of any offspring due to his social status. This paternal care evolved in sugar gliders as young are more likely to survive when parental investment is provided by both parents. In the sugar glider, biparental care allows one adult to huddle with the young and prevent hypothermia while the other parent is out foraging, as young sugar gliders aren't able to thermoregulate until they are 100 days old (3.5 months).

Communication in sugar gliders is achieved through vocalisations, visual signals and complex chemical odours. Chemical odours account for a large part of communication in sugar gliders, similar to many other nocturnal animals. Odours may be used to mark territory, convey health status of an individual, and mark rank of community members. Gliders produce a number of vocalisations including barking and hissing.

Conservation
Under the prior taxonomy, the sugar glider was not considered endangered, and its conservation rank was "Least Concern (LC)" on the IUCN Red List. However, with newer taxonomic studies indicating that it has a small and restricted range, it is now thought to be far more sensitive to potential threats. For example, the species' native range was hit hard by the 2019-20 Australian bushfires, which occurred just a few months prior to the publishing of the study indicating the true extent of its range. Sugar gliders use tree hollows, making them especially sensitive to intense fires. However, despite the loss of natural habitat in Australia over the last 200 years, it is adaptable and capable of living in small patches of remnant bush, particularly if it does not have to cross large expanses of cleared land to reach them. Sugar gliders may persist in areas that have undergone mild-moderate selective logging, as long as three to five hollow bearing trees are retained per hectare. Although not currently threatened by habitat loss, the ability of sugar gliders to forage and avoid predators successfully may be decreased in areas of high light pollution.

Conservation in Australia is enacted at the federal, state and local levels, where sugar gliders are protected as a native species. The central conservation law in Australia is the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The National Parks and Wildlife Act 1974 is an example of conservation law in the state of South Australia, where it is legal to keep (only) one sugar glider without a permit, provided it was acquired legally from a source with a permit. A permit is required to obtain or possess more than one glider, or if one wants to sell or give away any glider in their possession. It is illegal to capture or sell wild sugar gliders without a permit.

In captivity
In captivity, the sugar glider can suffer from calcium deficiencies if not fed an adequate diet. A lack of calcium in the diet causes the body to leach calcium from the bones, with the hind legs first to show noticeable dysfunction. Calcium to phosphorus ratios should be 2:1 to prevent hypocalcemia, sometimes known as hind leg paralysis (HLP). Their diet should be 50% insects (gut-loaded) or other sources of protein, 25% fruit and 25% vegetables. Some of the more recognised diets are Bourbon's Modified Leadbeaters (BML), High Protein Wombaroo (HPW) and various calcium rich diets with Leadbeaters Mixture (LBM). Iron storage disease (hemochromatosis) is another dietary problem that has been reported in captive gliders and can lead to fatal complications if not diagnosed and treated early.

A large amount of attention and environmental enrichment may be required for the highly social species, especially for those kept as individuals. Inadequate social interaction can lead to depression and behavioural disorders such as loss of appetite, irritability and self-mutilation.

As a pet
In several countries, the sugar glider (or what was formerly considered to be the sugar glider) is popular as an exotic pet, and is sometimes referred to as a pocket pet. In Australia, there is opposition to keeping native animals as pets from Australia's largest wildlife rehabilitation organisation (WIRES), and concerns from Australian wildlife conservation organisations regarding animal welfare risks including neglect, cruelty and abandonment.

In Australia, sugar gliders can be kept in Victoria, South Australia, and the Northern Territory. However, they are not allowed to be kept as pets in Western Australia, New South Wales, the Australian Capital Territory, Queensland or Tasmania.

DNA analysis indicates that "the USA (sugar) glider population originates from West Papua, Indonesia with no illegal harvesting from other native areas such as Papua New Guinea or Australia". Given that the West Papuan gliders have been tentatively classified as Krefft's gliders (albeit to be changed in the future), this indicates that at least the captive gliders kept in the United States are Krefft's gliders, not sugar gliders.

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title: Sugar glider