Hi everyone! I posted a while back about possibly doing my senior thesis on gliders. For now, I wrote a 12 page term paper and did a 15 minute presentation on them.

Most of my sources are articles from my college's library databases that are otherwise difficult to get to, so I thought some of you might be interested in some of the content.

If you paste this into word it should be easier to read. I apologize if I have anything wrong, I was working with a very limited amount of scholarly sources.

Claire L.
SLSC 4820
17 April 2014
The Importance of the Sociobiological Behavior of Sugar Gliders to Pet Owners
Exotic pets, basically anything not domesticated, including things like rabbits and guinea pigs, have become very popular in recent years and while most pet owners undoubtedly love their exotics, many people, family veterinarians included, do not understand the nature of these precious creatures. Sugar gliders (Petaurus Breviceps) are small, nocturnal, highly social marsupials native to Australia and New Guinea, who were introduced into the United States as pets in 1994 and have become increasingly popular ever since. Twenty years have passed and most people have either never heard of them or do not fully understand that they are exotic animals and as such are more demanding than typical household pets. Those that do understand seem to have a difficult time agreeing on the proper way to care for them. Some of the reasons sugar gliders are so difficult to care for are that they have small, delicate systems, complicated social hierarchies, are heavily dependent on olfactory communication, prefer to eat certain insects, suck the sap of certain trees, and have an anatomy not familiar to most Americans (Sobie, 2010, pg. 181-183). An understanding of how sugar gliders behave in nature would be beneficial to not only any interested pet owners, but also to any veterinary or zoological professional that may have to care for them at some point. To illustrate just how social they are, they have even been included in studies about human depression because they have been known to self mutilate from lack of social stimuli (Brown, 2002, pg. 270; Jones, Stoddart & Mallick, 1995, pg. 476).
Sugar gliders draw people in with their small size, large protruding eyes, elf-like ears, attractive coloring, and most importantly, their highly social nature. Many of the traits that make sugar gliders appealing pets, as well as the traits that make people wary of them, have evolutionary purposes that should be taken into account when considering gliders as pets. For example, the size and placement of their eyes is to aid these nocturnal omnivores in finding food and give them optimal depth perception when gliding. With eyes designed to see in situations with minimal lighting, it is cruel to try to subject them to a diurnal sleep schedule or expose them to excessive light during the night. Both their eyes and ears play important roles in navigating foliage and avoiding predators (Sobie, 2010, p.182, 185).
People are often offended by the smell gliders give off and try to bathe them or want to have their scent glands surgically removed, assuming that these glands are not important in captivity. Gliders are actually very clean animals and much like cats, it is not necessary to bathe them (MacPherson, 1997, pg. 55). What these people do not realize is that chemical communication, especially scent-marking, is the primary means by which sugar glider colonies communicate and remain socially cohesive. Wild sugar glider colonies are composed of up to twelve adults including one to three males with a strong hierarchal social structure. Using olfactory communication they harmonize many of their behavioral patterns including their sleep-wake cycle, grooming, and general activity (Sobie, 2010, pg. 182-183; Kleinknecht, 1984, pg. 191-192). Pet gliders are also known to urinate on their owners, which is essentially a way of distinguishing the owner as part of their community (Eisenberg and Kleiman, 1972, pg. 7). Although an animal in captivity does not typically need to mark its territory or ward off predators, contrary to the assumptions of some people, this does not mean that their scent-based communication becomes useless.
Chemical signals are processed by receptors such as the nerve endings in the olfactory mucosa or epithelium located in the nasal cavity and the taste buds of the tongue. The specialized receptor neurons responsible for olfaction are located in the olfactory epithelium, which in marsupials is organized into the little known vomeronasal organ. In all mammals the organ is an encapsulated structure on each side of the nasal septum located near the floor of the nasal cavity. The olfactory epithelium is connected to the olfactory bulb of the brain through the vomeronasal nerve. It has been shown in some species that neural activity travels from the vomeronasal organ through various structures before reaching the hypothalamus where it may influence sexual and feeding behaviors. Tongue movements, excessive salivation, and changes in breathing have been associated with the stimulation of the organ (Eisenberg & Kleiman, 1972, pg. 2-3).
There have been five scent glands identified in sugar gliders. All gliders have a urogenital proctodeal gland, which emits an airborne chemical to ward off predators, and a paraproctal gland that opens into the cloaca. Females have scent glands in their pouches, which emit odors that are attractive to newborn sugar gliders and helps young joeys distinguish their mother from other females by day 74. It takes 94 days for joeys to be able to distinguish the difference in odor between two separate colonies. Males have large cutaneous frontal glands on their foreheads and sternal-throat glands that they use to mark members of their community. The gland on the forehead results in a bald spot that makes it easier to distinguish gender, which is often incorrectly perceived to be a health issue (Eisenberg & Kleiman, 1972, 6-7, 13; Sobie, 2010, pg. 183).
All of the male scent glands are testosterone dependant and go through cycles of development and decline. Dominant males, as is common in a diverse range of species, have the highest levels of testosterone and the lowest levels of cortisol. When their social status is challenged, the plasma concentration in the testosterone either rises or falls based on the outcome. It has been shown that when there is instability in the social hierarchy of many animals the dominate male’s cortisone levels can go as high as those of the subordinate males. Dominate males mark their entire colony with their glandular secretions, giving each colony a distinct scent (Mallick, Stoddart, Jones & Bradley, 1994, pg. 1131; Eisenberg and Kleiman, 1972, 10-13).
There was a study done by Mallick et. al (1994) at the University of Tasmania to better understand the relationship between plasma concentrations in testosterone and total cortisol levels along with several behavioral differences between socially dominant and socially subordinate gliders and what happens endocrinologically and behaviorally when a dominant male is transplanted into a different stable colony. The study was comprised of four stable colonies composed of four males and one female each with their own light and temperature controlled 2x2x2 meter room with two nesting boxes. To determine social rank they were observed for five successive days for one hour a day starting when the food bowls were introduced. Not surprisingly, the most dominant male fed first and the most subordinate would not even approach the bowl until after all other males had eaten. With the use of stopwatches, the number of wins, social sniffs, visual scans of the room, scent markings, the distance moved, the speed of movement, and the duration of time spent in the nesting box of the most dominate and the most subordinate individuals were recorded. Blood, body weight, and plasma androgen concentration were sampled, tested, and recorded daily (pg. 1132.)
In the baseline study the number of occurrences of specified behaviors and durations of activities was recorded during the first three hours of darkness over two weeks. In the experimental study, which lasted three weeks, information was recorded about two colonies into which a foreign socially dominant male was introduced in the same manner as the baseline study. Here it was proven that dominant male sugar gliders do have higher plasma testosterone concentrations as well as lower cortisone levels than subordinate males. Although dominates are heavier and spend more time in the nest box than subordinates, they win the most conflicts, scent-mark more often, scan the area more, are faster and more active. Subordinate males did not scent-mark or win any social conflicts. The formerly dominant males quickly lost their social status and assumed all of the behavior patterns previously noted of originally subordinate males. The only behavior that did not change was the number of social sniffs and visual scans of the area. Castration has been found to eliminate the scent-marking ability of the sternal gland, giving further evidence that scent-marking is positively correlated with plasma testosterone concentrations (Mallick et. al, 1994, pg. 1132-1133).
In a similar study the following year about a sociobiological model of depression by Jones, Stoddart, and Mallick (1995) the same four groups of gliders were used, kept in the same housing, and data was collected in the same way. The baseline and experimental studies were conducted in the same way with the same resulting data, but instead of looking at the chemical aspects that changed in the experimental study, they compared their findings to human depression. The fact that when a dominate male glider is displaced into a new colony, it does not assume the second place in the hierarchy, but goes straight to the bottom is thought to be the human cognitive equivalent of a major loss of self-esteem. Comparisons were drawn between the sudden lack of food intake and rapid weight loss in the animal and the anorexia of depression and between the dramatically decreased amounts of social activity in the animal and the social withdrawal present in human depression. These behaviors most closely resemble affective disorder and dysthymia, which are two common human depressive syndromes. Both human depression and the actual emotions these animals appear to experience are not understood well enough to draw any conclusive results (pg. 476-478). The sugar glider depression model is not likely to be useful for studies of the evolution of depression because it is not likely that severe depressive-like states have been of any kind of adaptive importance. It is suggested that the severe response observed in this study may have been due in part to the captive environment (Brown, 2002, pg. 270).
One of the first mistakes people make is to think it is ok to have a solitary glider, which typically results in behavioral and physiological distress. The fact that moving a dominate male to a new colony results in his becoming the most subordinate instead of assuming the second position shows how distressing it is for gliders when their social hierarchy is manipulated, let alone eliminated. In fact, it is suggested that this massive change in hierarchy results in what can be compared to the massive loss of self esteem in humans, as mentioned above, which is why gliders have become a model for human depression studies (Jones et. al 1995, p. 476). Although in nature a colony would normally consist of about five to twelve members with one to three males, it has been shown that in captivity having at least two or more bonded gliders with any combination of genders adequately fulfills their social requirements (Sobie, 2010, pg. 188).
While the 24-hour light-dark cycle is the most important factor in synchronizing circadian rhythms, in animals entrained by light-dark cycles social stimuli also plays a factor. Kleinknecht (1984) performed a study on sugar gliders to see how social housing or a lack thereof affects their circadian rhythms. The study involved two male and two female sugar gliders whose activity was recorded electro-acoustically while being observed through an IR television camera when housed both individually and in male-female pairs with both normal light-dark cycles and constant illumination. The animals were kept in wire-mesh cages with a nest box and climbing poles, which were mounted in wooden soundproof illumination boxes. While kept in light-dark conditions, animals were observed three times individually and three times as pairs. In constant illumination periods lasting 24 hours, each pair was observed four times (pg. 189-190).
When the first pair was housed together under light-dark conditions both the female and the male had increased amounts of locomotion activity, a decreased amount of orientation movements, and a decreased amount of time spent grooming compared to when housed alone. In the second pair the female had increased amounts of locomotion activity, which was particularly low when kept singularly, and orientation movements and a decreased amount of time spent grooming while the male’s locomotion activity went from especially high to about normal while the rest of his activities did not change substantially. In both cases the animals harmonize so that their behavioral patterns become more similar. It is suggested that olfactory communication is responsible for this synchronization, however since the animals housed in constant illumination did not synchronize their behaviors, having a normal light-dark cycle clearly plays an important role (Kleinknecht, 1984, pg. 191-192).
Taken together with the information on scent marking the three studies described thus far all support the idea that keeping a solitary glider is not the best idea. The studies on behavioral endocrinology and sugar gliders as a model for human depression show that social displacement can have a major effect on body chemistry and behavior and show the significance of sugar glider social hierarchal structure (Mallick et. al, 1994, 1131-1135; Jones et. al, 1995, 475-479). The study on circadian rhythms by Kleinknecht (1984) shows that social housing has a measurable effect on normal functionality (pg. 191). This scientific evidence simply backs up the observable difference having a cage mate or two can have on a glider (Sobie, 2010, pg. 183).
Those interested in breeding sugar gliders should be aware of the unique way in which marsupials give birth and how gliders raise their young. There is not much available research on the mechanics of sugar glider reproduction specifically, but gliders are considered possums and since most possum species reproduce the same way, what is known about possum reproduction can be applied to them (Dierenfeld, 2009, pg. 211). In all marsupial births, the offspring leave the uterus when they are still essentially embryos and must crawl to their mother's pouch unaided before attaching to a nipple to finish developing. The ways in which they locate the pouch as well as what neural mechanisms are used in the process vary from species to species have not been thoroughly studied. There are at least three distinct forms of marsupial birth, which are separated into Didelphidae (opossums) and Phalangeroidea (possums and kangaroos), Permalidae (bandicoots), and the carnivorous Dasyuridae. In opossums, possums, and kangaroos, newborns crawl from the urogenital sinus to the pouch. In contrast, bandicoot newborns remain attached to the placenta by the umbilical cord while they swim from the urogenital sinus to the pouch and Dasyuridae newborns are expelled into a column of fluid, which they swim up to the tunnel between the urogenital sinus and the pouch before moving into the pouch (Gemmell and Nelson, 2004, pg. 53).
It is thought that the marsupial method of reproduction may be an adaptation to the dry and unpredictable climate of Australia. It costs very little energy to have young that complete embryological and later development attached to a teat in the mother’s pouch instead of in the womb. The estrus cycle of marsupials is not inhibited by gestation allowing for post-partum estrus and mating. Eggs that were fertilized during post-partum mating can go into fetal diapause, which is essentially a form of suspended animation, which they come out of when the suckling joeys leave the pouch. This strategy is used in nature if the environment becomes too hostile and milk production becomes insufficient to the point that the young that are on the teat die. Fetal diapause is also the reason why two litters in a breeding season is not uncommon. (Gemmall and Nelson, 2004, pg. 53; Sobie, 2010, pg. 186).
Glider reproductive tracts include two lateral genitalial canals with one median birthing canal, which merge and join with the urethra to form the urogenital sinus, which is just before the cloaca. Males have bifurcated genitaliaes to match the split genitalias, which are often mistaken as worms and owners have been known to try to remove it on their own. Among most possum species, sugar gliders included, gestation lasts 16-18 days and produces one to four young. At the time of birth sugar glider joeys are not much bigger than the eraser on a pencil weighing in at about 0.2 grams and have well enough developed forelimbs to be able to climb from the urogenital sinus to the pouch. Inside the pouch there are two mammae which each have two teats and about 81% of the time there are two joeys to a litter (Gemmell and Nelson, 2004, pg. 55; Sobie, 2010, pg. 186). After about two months, as gliders get too big to fit in the pouch, they begin to emerge tail first with the head being last. Sometimes it takes a few days before they will take their head out of the pouch for the first time. Once out of pouch joeys only put their heads back into the pouch to feed. Gliders typically become sexually mature between 12 and 14 months out of pouch. Joeys ride on the backs and stomachs of both males and females and males are usually very attentive to their young (Macpherson, 1997, pg. 38-39).
The dominant male is responsible for about 75% of conceptions each year in the wild. During times of abundant food, usually from June to November, this male breeds the adult females multiple times as gliders naturally operate on a 29-day polyestrus cycle. Subordinate males rarely mate, however the sons of the dominant male have been known to help provide care to their young siblings. It has been observed that males prefer grasping the coat of the females with his fore paws to clasping her with his forelegs before beginning copulation (Sobie, 2010, pg. 183-186).
The next mistake people make is to put a sugar glider in something like a hamster cage with nothing to eat but “glider pellets” that are essentially cat food and a few apple slices. Wild gliders live in the hollows of trees in the woodland forests of their native countries and have a special affinity for the forest canopy. As their name suggests they have gliding membranes called patagia, unique to petaurid marsupials, which is their primary mode of long distance locomotion extending from their forelimbs to their hind limbs. This makes them appear much like a flying squirrel; however, contrary to popular belief the two species are not related and are an interesting case of convergent evolution (Sobie, 181-183, 188). Many people try to put leashes or harnesses on gliders, which can seriously harm their tiny skeletons if they try to run or jump, and a harness can tear the delicate patagia.
Putting together a proper sugar glider cage is all about mimicking the forest. They are highly energetic and active creatures with a need to glide and climb and thus require large flight cages that are taller than they are wide. The absolute minimum cage size has been suggested to be 50.8x50.8x76.2 centimeter for two gliders, however a 1.8x1.8.x1.8 meter cage is more appropriate. The ideal cage size is the largest available cage that will fit in a space while still being manageable. If a cage is not floor to ceiling, it should be placed as high as possible and on top of something that does not make any type of noise to give gliders the sense that they are high up. Cage wires should be spaced so that gliders can climb without getting their toes stuck, but cannot slip out. When choosing a cage material, the fact that gliders can chew through tree bark should be taken into consideration. Cages should be kept away from direct sunlight, as it is known to give nocturnal animals retinal cancer. A room with windows or a light that is on a timer is important to give them a sense of day and night to maintain a normal circadian rhythm and so that they know when to eat, feed, and sleep (Kleinknecht, 1984, pg. 191). Ideal temperature is between 18 and 24 degrees Celsius. Some exposure to UV light is important to produce vitamin D. Daytime noise should be kept to a minimum (MacPherson, 1997, pg. 16-18; Sobie, 2010, pg. 188).
Cage accessories should be hung at the top level of the cage because gliders in nature are more comfortable in the treetops. It is important that all cage accessories be glider proofed, meaning nothing their small toes can get caught in, nothing that can be gnawed through, and nothing that can be swallowed. Wild gliders sleep huddled up together in the hollows of trees and therefore cages require multiple hideouts like a wood, wicker, or plastic nesting box, bag, or pouch with an opening that is large enough for a female with large babies in her pouch and is of adequate size to hold all or most of the colony. One hideout will not suffice because they are not limited in nature to one hollow tree. It is important to have some type of “branches” and perches to further mimic treetops. Actual branches from live or winter-dormant trees may be used and are to be replaced once the bark has been stripped and they have become soiled. As alternatives to real wood many glider owners have been known to use various kinds of rope, fleece rope, mesh, and chains without issue so long as they are glider proofed and properly attached. A variety of different kinds of perches, shelves, and ladders should be implemented to create multiple levels (MacPherson, 1997, pg.16-20).
In the wild, sugar glider diets consist of arthropods, eucalyptus sap, acacia gum, manna, honeydew, nectar, and pollen. In the fall and winter their diet mostly consists of plant exudates like wattle gum, eucalyptus sap, and eucalyptus nectar while in the spring and summer, insects are preferred even though plant exudates are more abundant, most likely to obtain the protein needed for reproduction. Gliders use their large front teeth, which are characteristic of possum species to cut into the bark of trees to obtain things like insects and sap, hence why they are sometimes referred to as “sap suckers” (Smith, 1982, pg. 149-152; Sobie, 2010, pg. 187).
In captivity it is clearly not practical to provide gliders with their natural diet and although there are many different captive diets available with no particular one being optimal, there are some basic guidelines. Protein, calcium, phosphorous, and vitamin D are the main components of most suggested diets. There is usually a protein source served with fresh fruit and vegetables. Successful captive protein sources have included imported Australian pollen, certain insects, and various kinds of dry food. Since gliders in the wild must forage for food, making use of their large incisors to cut into trees for bugs and sap, an important way to keep them mentally stimulated and happy is to simulate these natural foraging behaviors. Food and water should be in various locations throughout the cage, with some food sources being more difficult to get to than others. Foraging toys can be anything glider safe that treats can be hidden in, especially if it can be hung in different parts of the cage, the greater the challenge the better. Honey sticks or straws are a common treat that simulate sap-sucking behavior (Dierenfeld, 2009, pg. 209-215; Sobie, 2010, pg. 187).
Sugar gliders are visually attractive exotic animals that have been useful in a great deal of research ranging from behavioral endocrinology and circadian rhythms to human emotions. While they look like flying squirrels, they are actually small, highly social petaurid marsupials native to Australia and New Guinea that rely heavily on olfactory communication. They form tight knit socially cohesive colonies of up to 12 members with well-established hierarchal structures that live together in the hollows of trees. Both males and females actively partake in the care of their offspring, called joeys (Sobie, 2010, pg. 183-188). In captivity, gliders can make very rewarding pets for those who take their natural habitat and behavioral patterns into consideration. With patience and attention to detail, a captive glider habitat can easily give its inhabitants a home that mimics their natural environment enough for them to feel safe and maintain normal behavioral patterns like foraging, normal sleep-wake cycles, and of course, socialization.

Works Cited

Brown, G.W. (2002). Context and evolution in the origins of depression.pdf. Journal of Health and Social Behavior 43(3) 255-276. Retrieved from JSTOR

Dierenfeld, E.S. (2009). Feeding behavior and nutrition of the sugar glider (Petaurus Breviceps).pdf. Vet Clin of North Am Exot Anim Pract 12(2), 209-215. Retrieved from PubMed doi:10.1016/j.cvex.2009.01.014

Eisenberg, J.F., Kleiman, D.G. (1972). Olfactory communication in mammals.pdf. Annual Review of Ecology and Systematics 3, 1-32. Retrieved from JSTOR

Jones, I. H. (1995). Towards a sociobiological model of depression: A marsupial model (Petaurus breviceps).pdf. The British Journal of Psychiatry 166(4), 475-479. Retrieved from Academic Search Complete

Kleinknecht, S. (1985). Lack of social entrainment of free-running circadian activity rhythms in the Australian sugar glider.pdf. Behav Ecology Sociobiol 16, 189-193. Retrieved from Academic Search Complete

Macpherson, C. (1997). Sugar Gliders (A Complete Pet Owner’s Manual). Hauppauge, NY: Barron’s Educational Series, inc.

Mallick, J., Stoddart, D.M., Jones, I., Bradley, A.J. (1994) Behavioral endocrinological correlates of social status in the male sugar glider.pdf. Physiology & Behavior 55(6), 1131-1134. Retrieved from Academic Search Complete

Nelson, J., Gemmell, R. (2004). Implications of marsupial births for an understanding of behavioural development.pdf. International Journal of Comparative Psychology 17, 53-70. Retrieved from Academic Search Complete

Smith, A.P. (1982). Diet and feeding strategies of the marsupial sugar glider in temperate Australia.pdf. Journal of Animal Ecology 51(1), 149-166. Retrieved from JSTOR

Sobie, J.L. (2010). Sugar Gliders. In Tynes, V.V. (Ed.), Behavior of Exotic Pets (pp. 181-188). West Sussex, UK: John Wiley and Sons Ltd.

Wow! I actually read it all! Very interesting love the parts about behavior in the while and dominance, and reading about breeding and how to properly take care of them is important!! I love all my babies thanks for this. There may be people that genuinely love there babies but may not be giving them proper care or really don't know anything about how there behavior really is or about there life in the wild! Also this paper may help many of your colleagues who were thinking about owning a glider ask themselves is a glider the right pet for me? Let ous know how this goes for u at your collage! thanks!

Thanks, I appreciate the kind words. I got a high B on the presentation, I haven't gotten the grade back on the paper itself yet. It's just the final paper for one class, so it won't do more than get me a grade.

Can you send me the word file to my personal email? You can private message me so I can see...my iPads not letting me pull it up all the way :(

I got a 96 on the paper :D