Visitors to Barro Colorado Island usually find that white-nosed coatis (Nasua narica) are the most obvious component of the mammal community. They are readily seen because female coatis and young are gregarious and noisy by nature, and active during the day. Coatis are relatively numerous on the island, so chances of encountering some coatis on a short walk are quite good. BCI coatis have been the subjects of three long-term ecological studies as well as several shorter studies since the late 1950s. As a result of these contacts with scientists, many coatis are habituated to observers and often do not flee from humans.
White-nosed coatis range from the very southwestern United States (Arizona, New Mexico and Texas) southward throughout Mexico and Central America (including all of Panama), and into northwestern Colombia (west of the Gulf of Uraba). Throughout their range, coatis occupy a diversity of wooded habitats from temperate oak and pine forests to lowland rain forests and cloud forests, and occasionally into deserts and savannas.
Two species are now recognized: Nasua narica, the subject of this account, and Nasua nasua, which is found throughout South America. In the past, over 30 populations have been incorrectly designated as separate species based on variable characteristics such as coat color differences. Confusion over the status of males, which live alone, led early researchers to designate additional separate species names (Nasua solitaris and Nasua sociabilis ) for solitary adult males and for gregarious band members of Brazilian coatis. Many of the common names still used in North and South America perpetuate the confusion. Common names for white-nosed coatis include coati and gato solo (Panama), pizote and pizote solo (Costa Rica, Honduras), chic and sis (Mayan), quash (Belize), tejon and tejon solo (Mexico), and in the United States: chulo, chulo bears, coati and coatimundi. The common name coati is of Tupian Indian origin, referring to the coatis* habit of sleeping with the nose tucked on the belly. Although coati monde from the Brazilian vernacular properly refers to solitary males, it is often used to denote all coatis. Through usage, the spelling has become coatimundi. It*s easy to see why scientists designate scientific names to species and are careful to define and use them precisely.
White-nosed coatis are readily identified by their long, slender, non-grasping tail which is equal in length to the head and body, and by their long and flexible snout that protrudes beyond the end of the lower jaw. The claws are long and the feet are flat with naked soles. On Barro Colorado Island, adult males weigh approximately 5 kg and are approximately 114 cm from the tip of the nose to the tip of the tail. Adult females are smaller, weighing approximately 3.7 kg and measuring about 103 cm in length. Coatis vary in coloration throughout their range, even within populations. Breeding experiments have shown that even within a litter, siblings may vary in color. On Barro Colorado Island the usual color is dark brown, nearly black, often overlaid with some silver. The neck and shoulders are whitish, as are the muzzle, chin, and throat. Thin whitish streaks extend from the muzzle between and over the eyes. The ears are often white-tipped. The tail is ringed (more distinct in young than in adults) and generally held vertically while the animal is feeding.
Fossil coatis are rare, and the fossil record and evolutionary history of this species is poorly understood. A few incomplete fossils exist from the United States and from South America (Brazil and Bolivia), and none from Central America. Most of the range of the species is or was tropical forest, which is not conducive to fossil formation. What little can be deduced from existing fossils suggests that the species may have diverged from a raccoon lineage approximately 4.5-9.5 million years ago. Laboratory studies that compare the DNA and proteins of coatis and other small carnivores confirm that the species is genetically most closely related to raccoons and ringtails. People often recognize this relationship because of the similar mask-like facial markings and ringed tails of these species.
Perhaps the most outstanding physical feature of a coati is its long, pointed snout. The area around the nose is rich in sensory receptors which result in an extremely heightened sense of smell. Numerous muscles allow great flexibility of the tip of the snout, which is used to poke into crevices and to seek out prey. Coatis curl their snouts in an amazing way above the water surface when drinking.
Coatis easily climb small trees and vines, and it can be very entertaining to watch a group of coatis feeding in treetops. They have more difficulty climbing the smooth trunks of large trees, and normally descend or ascend by moving out to the end of a limb and transferring to nearby branches of the same tree. Coatis can rotate their hind feet to descend from trees head first. The tail is not prehensile (that is, it cannot grasp), but does serve as a balancing tool during activity in trees. Coatis spend about 90% of their daytime hours foraging, and at least 90% of that foraging time is spent on the ground, even though they climb well. The forefeet contain long, powerful, blunt, and slightly curved claws, making coatis excellent diggers and shredders. While coatis can stand on their hind legs for short periods of time, they do not normally walk on just two feet. Running speed may reach 27 km/h, and one author noted that coatis can run for 3 hours when hunted by dogs. Coatis are also strong swimmers, and on several occasions individuals have been observed swimming in the Panama Canal.
On Barro Colorado Island, all coatis breed at the same time within a two- to four- week period in late January and early February. This period may shift slightly from year to year. Actual mating may occur in the trees or on the ground. BCI females may first breed at 22 months of age, although a few females may not breed until 46 months. All females may breed, or as few as 20% may breed, depending on ecological conditions such as food availability. Males may mate at 34 months of age, but due to intense competition between males, an individual may not successfully breed until his 4th or 5th year, if ever. More than one male may breed with the females of a given band during a single breeding season. In addition, the consorting male for a given band may vary year-to-year. After the mating season, males return to their solitary lifestyle, and pregnant females eventually separate from the bands to nest and give birth alone in a tree or den in April or early May. Gestation is approximately 70-77 days.
Young coatis weigh about 180 grams at birth, with body lengths of 255-275 millimeters. They open their eyes after 4-11 days, and begin to walk and hold their tail erect at around 11 days. Teeth begin to erupt at about 15 days. By 40 days, when females and their newborn young rejoin the band, juveniles weigh approximately 500 grams. Females on BCI give birth to one to six young and rejoin the band with an average of 3.5 surviving juveniles. When first brought from the nest, juveniles are small, incompletely developed, and have difficulty keeping up with the band. In turn, the band appears to restrict its movements at this time. During the first week after joining the band, females sometimes leave their young unattended in a temporary nest while they forage. Mothers nurse their young for up to 3 months after band reunion, with most nursing occurring during the band’s daily rest period. Adult females have been observed nursing, grooming, and babysitting the offspring of other females. Young males become solitary at the 24th or 25th month of age, when the testes of males descend into the scrotum. Coatis are relatively long-lived: in captivity, individuals are known to live more than 17 years. On BCI, the oldest known individuals are at least nine years old.
Despite belonging to the carnivore family, coatis are quite omnivorous, eating mostly invertebrates and fruit, as well as vertebrates and carrion when available. Major events in coati life history on BCI are closely timed to food availability. For example, birth occurs during the period of greatest fruit ripening. During the wet season in Panama, 89% of foraging time is spent searching for animal foods such as insects and spiders, while in the dry season this proportion drops to 54%; the remaining time is spent under fruiting trees. Food is found by smell rather than sight, by sniffing in the litter, and then is dug up or extracted from under bark, leaves, or clumps of debris. Coatis handle invertebrate prey, even toxic species such as tarantulas, by rolling them between their paws, quickly killing organisms that can bite or sting, and removing the various hairs, bristles, and spines that may make the prey distasteful or difficult to eat. Vertebrate prey such as lizards are pinned with the forepaws, and quickly bitten through the skull. Fruit is eaten both in trees and on the ground, and long climbs are commonly made to reach the outermost limbs of large trees. On Barro Colorado Island, Scheelea zonensis, Dipteryx panamensis, Spondias mombin, Ficus insipida, Quararibea asterolepis, and Tetragastris panamensis are important fruiting species. Some trees of these species produce so much fruit that a band may camp under a tree for several days, with occasional side trips to forage for animals to supplement their diet of sweets with protein.
Being omnivores on BCI is not easy because many species compete for the same foods. Visitors to BCI in the dry season often observe coatis feeding at the same trees with agoutis and squirrels, where the fruit is too abundant to protect and the competitors are too numerous to chase away. In Arizona, by contrast, a successful coati band was observed to usurp a deer carcass from a coyote. More typically, however, competition does not involve confrontation, threats, or fighting. In Panama, interactions with armadillos, agoutis, howler monkeys, squirrel monkeys, tapirs, peccaries, and squirrels are generally non-violent. Night monkeys, fruit-eating bats, and kinkajous compete with coatis for fruit in trees, but since they are nocturnal, they rarely encounter the coatis, who are sleeping while the others feed. White-faced monkeys are a different story: they are direct competitors, and will even kill juvenile coatis. Coatis feeding in trees descend to the ground when white-faced monkeys arrive, who may actively chase them from a tree. Harassment by monkeys also occurs on the ground, and even in trees that are not fruiting. However, coatis often sneak back under trees where white-faced monkeys are busy feeding, eating the ripe fruit that the monkeys drop.
Large cats such as pumas and jaguars, large hawks and eagles, snakes, and some monkeys prey on coatis. Much of the predation occurs on juveniles; one study on Barro Colorado Island found that 90% of the disappearances of juveniles occurs within three months of birth. Adult male coatis occasionally kill juvenile coatis. The cause and significance of this behavior remains unclear. Although an adult coati can defend itself very well, predation on adults does occur: one of the author’s adult male study animals was killed by a crocodile near the lab clearing, presumably while drinking or foraging near the shore of Gatun Lake. The $300 radio-collar the coati was wearing at the time of its disappearance continued to transmit radio signals for some time thereafter, sending information that indicated it was transmitting from the lake, making sounds that seemed both sad and ominous.
The population density of coatis on Barro Colorado Island is currently about 50-55 individuals/km2, which is higher than most other Neotropical sites that have been studied. However, large fluctuations may occur year-to-year due to disease or food availability, and periodic crashes in the BCI coati population have been recorded. The gregarious nature of coatis may facilitate the transmission of diseases and parasites and contribute to rapid population reductions. Home range sizes are somewhat smaller on Barro Colorado Island than in other studied tropical regions. Bands have home ranges of approximately 0.34 km2, and may overlap with some, although not all, neighboring bands. Solitary adult males have similarly-sized home ranges, which overlap with the ranges of many other males.
Coatis are highly gregarious, with several adult females and their immature offspring forming bands of up to 30 individuals, and occasionally more. On Barro Colorado Island, bands average 15 individuals, although this number may vary considerably within years due to mortality and the birth of juveniles. Bands are made up primarily of closely related individuals, although many bands also contain a few unrelated members. New bands may form by fission or fusion of existing bands. Migration of individuals between bands also occurs. Evolutionary explanations for the gregariousness of coati bands include: reduction of feeding niche overlap between males and females, anti-predator behavior, the protection of juveniles from predation by adult males, and a strategy that allows smaller females to access food that is aggressively guarded by large solitary males. Some males do associate with bands, perhaps to gain from the social grooming that removes ectoparasites, or for protection from potential predators and from other adult males. Fighting between adult males is common, especially during the breeding season, and 30% of males display bite wounds or broken canines.
Coatis have a wide range of social behavior, including cooperative grooming, nursing, vigilance, and aggressive anti-predator behavior. Bands are usually slightly agonistic to other bands when they meet. However, peaceful interactions also occur, and are occasionally characterized be inter-group grooming sessions. Adult males that approach bands are generally aggressively chased away by one or several band members, including juveniles and subadults. Females often groom one another in an excited manner following such chases. During the breeding season males are submissive to females and immatures, and occasionally groom them. Bands often break into subgroups for several hours or occasionally 1-2 days.
Coatis do not voluntarily share food, nor do they store it. However, juveniles are tolerated by foraging adults, and juveniles can often be seen sniffing the muzzles of feeding adults. This behavior helps juveniles learn characteristics of food, as well as foraging techniques. While foraging, bands typically assume an elliptical outline, with subadults and adults forming the periphery, and juveniles aggregated in the center. Animals on the periphery protect juveniles through specialized vigilance behavior, cooperative attacks on potential predators, and assuming protective positions during flight from alarming stimuli. However, when pregnant females leave the group during the nesting season, bands assume a rank formation, a spatial organization efficient for foraging but not for defense. Vigilance levels of individuals are highest in small bands and lowest in large bands. When frightened, white-nosed coatis flee on the ground rather than into trees, and if startled in large trees, will often leap to the ground to escape. This can be quite startling to the observer, as coatis rain to the ground from as high as 5-10 meters.
Coatis are most active during daylight hours, and in undisturbed tropical forest habitats, sleep at night in the forest canopy. Juveniles are usually in the center of the band during rest and sleep periods, with adults on the perimeter. Rest periods of up to 2 h are also taken during the daylight hours, more frequently during the dry season in Panama, when fruit is abundant. In populated areas of tropical America where they are hunted for food by humans, coatis (as well as other diurnal species) have become more nocturnal.
During heavy rains, coatis become nervous, with the band grouping tightly together and young remaining close to their mothers. Invariably, the band runs for cover, such as tree buttresses, palm fronds, or dense brush piles and tree tops. After the rain ceases, coatis return to normal activities. During light rains, coati bands show little reaction, although they may travel at an increased pace, with juveniles often giving chitter vocalizations.
Coatis are highly vocal, with a rich repertoire of specific vocalizations for aggression, appeasement, alarm, and sexual contact between individuals. Certain vocalizations are only given by specific age or sex classes, with band members generally much more vocal than solitary adult males. Spectrographic and aural analyses indicate that the vocalizations of individual animals may be distinctive. Visual signals are also used, and include nose-up, head-down, and tail-switching displays. Scent marking occurs, and involves a perineal drag, usually on trees, logs, and vines. Although males scent mark year round, females perform this behavior most frequently just prior to the mating season.
Two very interesting behaviors have been observed among coatis that are indicative of the complexity and flexibility of coati behavior. First, BCI coatis have been observed to eat ticks from the coats of tapirs. This behavior is beneficial to the tapir who has parasites removed and to the coati who gets a protein-rich morsel to eat. Called a mutualistic behavior, it may have arisen when coatis and tapirs fed in close proximity at a feeding station in the laboratory clearing, and is likely culturally transmitted. It is presumed that coatis and tapirs do not normally mingle in the forest, but this is not known for certain. Second, and also likely learned, is the behavior of self-grooming and grooming of others with the resin of caraa, Trattinnickia aspera. This behavior is also likely acquired and maintained through cultural transmission, and may serve some pharmaceutical purpose. Similarly, white-faced monkeys and spider monkeys often rub fragrant leaves into their fur.
Coatis are important prey for subsistence hunters, and white-nosed coati population densities decline steeply with increased human hunting pressure. Indiscriminate predator control campaigns, such as poisoned baits, may also sharply impact coati populations. Although coatis are now legally protected in New Mexico (United States) and in Honduras, under the Convention on International Trade in Endangered Species, throughout most of its range, conservation and management issues have either not been addressed or are not effectively enforced.
Coatis are commonly captured and sold as pets; however, coatis do not make good pets. While cute and playful as juveniles, adult coatis are extremely powerful and temperamental. With their strong sharp claws and canines, coatis are difficult to handle and can easily harm humans. Furthermore, like raccoons, they have good manipulative skills and are capable of opening cabinets and getting into food containers or other belongings, so they are very destructive inside a house, and difficult to keep in a cage. Coatis carry a number of parasites and diseases that are transmissible to other pets and to humans. They are in turn susceptible to many common diseases that pets are often vaccinated against. Coatis are well-adapted to their natural habitat, and that’s where they should stay.
© Matthew Gompper 1997