Ring-tailed lemur

Appearance

The ring-tailed lemur is a relatively large lemur. Its average weight is 2.2 kilograms. Its head–body length ranges between 39 and 46 cm, its tail length is 56 and 63 cm, and its total length is 95 and 110 cm. Other measurements include a hind foot length of 102 and 113 mm, ear length of 40 and 48 mm, and cranium length of 78 and 88 mm.

The species has a slender frame and narrow face, fox-like muzzle. The ring-tailed lemur's trademark—a long, bushy tail—is ringed in alternating black and white transverse bands, numbering 12 or 13 white rings and 13 or 14 black rings, and always ending in a black tip. The total number of rings nearly matches the approximate number of caudal vertebrae. Its tail is longer than its body and is not prehensile. Instead, it is only used for balance, communication, and group cohesion.

Naming

Although the term "lemur" was first intended for slender lorises, it was soon limited to the endemic Malagasy primates, which have been known as "lemurs" ever since. The name derives from the Latin term "lemures", which refers to specters or ghosts that were exorcised during the Lemuria festival of ancient Rome. According to Carl Linnaeus's own explanation, the name was selected because of the nocturnal activity and slow movements of the slender loris. Being familiar with the works of Virgil and Ovid and seeing an analogy that fit with his naming scheme, Linnaeus adapted the term "lemur" for these nocturnal primates. However, it has been commonly and falsely assumed that Linnaeus was referring to the ghost-like appearance, reflective eyes, and ghostly cries of lemurs. It has also been speculated that Linnaeus may also have known that some Malagasy people have held legends that lemurs are the souls of their ancestors, but this is unlikely given that the name was selected for slender lorises from India. The species name, "catta", refers to the ring-tailed lemur's cat-like appearance. Its purring vocalization is similar to that of the domestic cat.

Following Linnaeus's species description, the common name "ring-tailed maucauco" was first penned in 1771 by Welsh naturalist Thomas Pennant, who made note of its characteristic long, banded tail. The now universal English name "ring-tailed lemur" was first used by George Shaw in his illustrated scientific publication covering the Leverian collection, which was published between 1792 and 1796.

Behavior

Troops are classified as multi-male groups, with a matriline as the core group. As with most lemurs, females socially dominate males in all circumstances, including feeding priority. Dominance is enforced by lunging, chasing, cuffing, grabbing and biting. Young females do not always inherit their mother's rank and young males leave the troop between three and five years of age. Both sexes have separate dominance hierarchies; females have a distinct hierarchy while male rank is correlated with age. Each troop has one to three central, high-ranking adult males who interact with females more than other group males and lead the troop procession with high-ranking females. Recently transferred males, old males or young adult males that have not yet left their natal group are often lower ranking. Staying at the periphery of the group they tend to be marginalized from group activity.

For males, social structure changes can be seasonal. During the six-month period between December and May a few males immigrate between groups. Established males transfer on average every 3.5 years, although young males may transfer approximately every 1.4 years. Group fission occurs when groups get too large and resources become scarce.

In the mornings the ring-tailed lemur sunbathes to warm itself. It faces the sun sitting in what is frequently described as a "sun-worshipping" posture or lotus position. However, it sits with its legs extended outward, not cross-legged, and will often support itself on nearby branches. Sunning is often a group activity, particularly during the cold mornings. At night, troops will split into sleeping parties huddling closely together to keep warm.

Despite being quadrupedal the ring-tailed lemur can rear up and balance on its hind legs, usually for aggressive displays. When threatened the ring-tailed lemur may jump in the air and strike out with its short nails and sharp upper canine teeth in a behaviour termed "jump fighting". This is extremely rare outside of the breeding season when tensions are high and competition for mates is intense. Other aggressive behaviours include a "threat-stare", used to intimidate or start a fight, and a submissive gesture known as "pulled-back lips".

Border disputes with rival troops occur occasionally and it is the dominant female's responsibility to defend the troop's home range. Agonistic encounters include staring, lunging approaches and occasional physical aggression, and conclude with troop members retreating toward the center of the home range.
Olfactory communication is critically important for strepsirrhines like the ring-tailed lemur. Males and females scent mark both vertical and horizontal surfaces at the overlaps in their home ranges using their anogenital scent glands. The ring-tailed lemur will perform a handstand to mark vertical surfaces, grasping the highest point with its feet while it applies its scent. Use of scent marking varies by age, sex and social status. Male lemurs use their antebrachial and brachial glands to demarcate territories and maintain intragroup dominance hierarchies. The thorny spur that overlays the antebrachial gland on each wrist is scraped against tree trunks to create grooves anointed with their scent. This is known as "spur-marking".

In displays of aggression, males engage in a social display behaviour called "stink fighting", which involves impregnating their tails with secretions from the antebrachial and brachial glands and waving the scented tail at male rivals.

Ring-tailed lemurs have also been shown to mark using urine. Behaviorally, there is a difference between regular urination, where the tail is slightly raised and a stream of urine is produced, and the urine marking behavior, where the tail is held up in display and only a few drops of urine are used. The urine-marking behavior is typically used by females to mark territory, and has been observed primarily at the edges of the troop's territory and in areas where other troops may frequent. The urine marking behavior also is most frequent during the mating season, and may play a role in reproductive communication between groups.The ring-tailed lemur is one of the most vocal primates and has a complex array of distinct vocalizations used to maintain group cohesion during foraging and alert group members to the presence of a predator. Calls range from simple to complex. An example of a simple call is the purr, which expresses contentment. A complex call is the sequence of clicks, close-mouth click series, open-mouth click series and yaps used during predator mobbing. Some calls have variants and undergo transitions between variants, such as an infant "whit" transitioning from one variant to another.

The most commonly heard vocalizations are the moan, early-high wail, and clicks.Historically, the studies of learning and cognition in non-human primates have focused on simians, while strepsirrhine primates, such as the ring-tailed lemur and its allies, have been overlooked and popularly dismissed as unintelligent. A couple of factors stemming from early experiments have played a role in the development of this assumption. First, the experimental design of older tests may have favored the natural behavior and ecology of simians over that of strepsirrhines, making the experimental tasks inappropriate for lemurs. For example, simians are known for their manipulative play with non-food objects, whereas lemurs are only known to manipulate non-food objects in captivity. This behaviour is usually connected with food association. Also, lemurs are known to displace objects with their nose or mouth more so than with their hands. Therefore, an experiment requiring a lemur to manipulate an object without prior training would favor simians over strepsirrhines. Second, individual ring-tailed lemurs accustomed to living in a troop may not respond well to isolation for laboratory testing. Past studies have reported hysterical behaviour in such scenarios.

The notion that lemurs are unintelligent has been perpetuated by the view that the neocortex ratio indicates intelligence. In fact, primatologist Alison Jolly noted early in her academic career that some lemur species, such as the ring-tailed lemur, have evolved a social complexity similar to that of cercopithecine monkeys, but not the corresponding intelligence. After years of observations of wild ring-tailed lemur populations at the Berenty Reserve in Madagascar and as well as baboons in Africa, she more recently concluded that this highly social lemur species does not demonstrate the equivalent social complexity of cercopithecine monkeys, despite general appearances.

Regardless, research has continued to illuminate the complexity of the lemur mind, with emphasis on the cognitive abilities of the ring-tailed lemur. As early as the mid-1970s, studies had demonstrated that they could be trained through operant conditioning using standard schedules of reinforcement. The species has been shown to be capable of learning pattern, brightness, and object discrimination, skills common among vertebrates. The ring-tailed lemur has also been shown to learn a variety of complex tasks often equaling, if not exceeding, the performance of simians.

More recently, research at the Duke Lemur Center has shown that the ring-tailed lemur can organize sequences in memory and retrieve ordered sequences without language. The experimental design demonstrated that the lemurs were using internal representation of the sequence to guide their responses and not simply following a trained sequence, where one item in the sequence cues the selection of the next. But this is not the limit of the ring-tailed lemur's reasoning skills. Another study, performed at the Myakka City Lemur Reserve, suggests that this species along with several other closely related lemur species understand simple arithmetic operations.

Since tool use is considered to be a key feature of primate intelligence, the apparent lack of this behavior in wild lemurs, as well as the lack of non-food object play, has helped reinforce the perception that lemurs are less intelligent than their simian cousins. However, another study at the Myakka City Lemur Reserve examined the representation of tool functionality in both the ring-tailed lemur and the common brown lemur and discovered that, like monkeys, they used tools with functional properties instead of tools with nonfunctional features. Although the ring-tailed lemur may not use tools in the wild, it can not only be trained to use a tool, but will preferentially select tools based on their functional qualities. Therefore, the conceptual competence to use a tool may have been present in the common primate ancestor, even though the use of tools may not have appeared until much later.

Habitat

The ring-tailed lemur is diurnal and semi-terrestrial. It is the most terrestrial of lemur species, spending as much as 33% of its time on the ground. However it is still considerably arboreal, spending 23% of its time in the mid-level canopy, 25% in the upper-level canopy, 6% in the emergent layer and 13% in small bushes. Troop travel is 70% terrestrial.

Reproduction

The ring-tailed lemur is polygynandrous, although the dominant male in the troop typically breeds with more females than other males. Fighting is most common during the breeding season. A receptive female may initiate mating by presenting her backside, lifting her tail and looking at the desired male over her shoulder. Males may inspect the female's genitals to determine receptiveness. Females typically mate within their troop, but may seek outside males.

The breeding season runs from mid-April to mid-May. Estrus lasts 4 to 6 hours, and females mate with multiple males during this period. Within a troop, females stagger their receptivity so that each female comes into season on a different day during the breeding season, reducing competition for male attention. Females lactate during the wet season, from December through April, when resources are readily available. Females gestate during the dry season, from May through September, when resources are low. Females give birth during seasons where resources, such as flowers, are in peak. Gestation lasts for about 135 days, and parturition occurs in September or occasionally October. In the wild, one offspring is the norm, although twins may occur. Ring-tailed lemur infants have a birth weight of 70 g and are carried ventrally for the first 1 to 2 weeks, then dorsally.

The young lemurs begin to eat solid food after two months and are fully weaned after five months. Sexual maturity is reached between 2.5 and 3 years. Male involvement in infant rearing is limited, although the entire troop, regardless of age or sex, can be seen caring for the young. Alloparenting between troop females has been reported. Kidnapping by females and infanticide by males also occur occasionally. Due to harsh environmental conditions, predation and accidents such as falls, infant mortality can be as high as 50% within the first year and as few as 30% may reach adulthood. The longest-lived ring-tailed lemur in the wild was a female at the Berenty Reserve who lived for 20 years.Mittermeier et al. 2006, pp. 246–249. sfn error: no target: CITEREFMittermeierKonstantHawkinsLouis2006 In the wild, females rarely live past the age of 16, whereas the life expectancy of males is not known due to their social structure. The longest-lived male was reported to be 15 years old. The maximum lifespan reported in captivity was 27 years.

Food

The ring-tailed lemur is an opportunistic omnivore primarily eating fruits and leaves, particularly those of the tamarind tree, known natively as "kily". When available, tamarind makes up as much as 50% of the diet, especially during the dry, winter season. The ring-tailed lemur eats from as many as three dozen different plant species, and its diet includes flowers, herbs, bark and sap. It has been observed eating decayed wood, earth, spider webs, insect cocoons, arthropods and small vertebrates. During the dry season it becomes increasingly opportunistic.