The Raccoon Family: Cacomistles

Ringtail

While true raccoons and coatis were first scientifically described during the 18th century, the third member of the raccoon family that's native to the United States was not described until 1830, by Heinrich Lichtenstein - who later went on to found the Berlin Zoo. It's unclear (at least to me) exactly what he thought the animal was. So far as I can translate the original German, his original description says that it's somewhere between a civet and a coati in appearance, but also looks quite like a fox. Based on which, he gave it the scientific name Bassaris astutus, a mixture of Greek and Latin that roughly translates as "cunning fox".

The scientific name didn't stand, because it turned out that the first part of it had already been used for a kind of butterfly. Furthermore, while he originally referred to the animal by its Spanish name "cacomixtle", since the specimen he knew of came from somewhere near Mexico City, in English we now call it a ringtail (Bassariscus astutus) or, less accurately, a "ring-tailed cat". Even so, in many parts of the US, an Anglicised form of the Spanish name is still in wide use. 

Ringtails are found throughout central and northern Mexico, and much of the American Southwest and Pacific coast. In the east, they reach the Mississippi River in Louisiana and Arkansas, while their northern limit runs from Kansas to Nevada and then up the coast from California to southern Oregon. Within this area, they prefer areas with rocky terrain but this can vary from dry coniferous forests on lower mountain slopes to open chaparral or even desert.

Ringtails are much smaller than the common raccoon, and slender with it, weighing only around 1 kg (2 lbs) and with a head and body length of around 30 cm (1 foot). But, with their black-and-white facial markings and striped tail, a general resemblance to a raccoon is certainly evident. Perhaps the most notable feature is the tail, which is slightly longer than the head and tail combined. A distinguishing feature is that the rings do not run all the way around, with the underside of the tail being pure white.

The feet have partially retractile claws and can swivel 180 degrees, helping them climb rocky surfaces with ease - like many arboreal mammals, but unlike humans, they climb down headfirst. The muscles attached to the tendons in their toes are particularly strong, giving them a powerful grip, although apparently, the ankles require only skeletal, and not muscular, adaptations to rotate as they do.

Like other members of the family, ringtails are omnivorous, with most of their droppings contain a mix of both plant and animal matter. Much of the plant-based part of their diet consists of fruit, especially in the summer, although they also eat leaves, moss, and lichen when that's what's available and have been reported to feed on cactus nectar. They can be important seed dispersers; in one forest in Mexico, they were reported as particularly benefiting junipers and prickly pears. 

They are similarly opportunistic when selecting animal prey, mostly feeding on small creatures such as mice, voles, crickets, and beetles, but including some up to the size of rabbits, not to mention birds and reptiles. They also scavenge on larger animals, and even enter caves to feed on bats. Some of the invertebrates they eat are venomous including, for example, scorpions. 

Despite being common, ringtails are not frequently seen in the wild, which may explain why they weren't described scientifically until 1830. This is mainly because they are highly nocturnal, spending the day sheltering in rock crevices or hollow trees. Indeed, they really seem to dislike sunlight, preferring to head to their shelter before dawn and not typically leaving until after sunset. Having said which, they are as opportunistic with their den sites as with their diet, rarely spending more than three consecutive nights in the same place. When it comes to rock dens, they prefer those on moderately steep slopes, possibly because those are easier for them to climb than for their predators. 

They are generally solitary, marking their territory by leaving their droppings in clearly visible locations and also scent-marking by spraying on exposed objects. They also have a wide repertoire of sounds for communication, including whistles to indicate tolerance, growls and hisses to indicate hostility, and barks for sudden alarm. Juveniles of both sexes make a chittering sound when distressed, while adult females make a very similar sound during the mating act.

Speaking of which, females only come into heat once a year, usually in March or April and are sexually receptive for no more than 36 hours. As one might expect, the male will take as much advantage of this as he possibly can, chasing the female and then mating several times an hour, gripping onto his partner for up to two minutes afterwards. The male usually heads off in the hopes of finding another receptive female after this; if he does hang around, she'll drive him off from her den before giving birth.  

Pregnancy is unusually short compared with other members of the raccoon family (ringtails are, after all, one of the smaller species) lasting 51 to 54 days and resulting in a litter of up to four young. They are born blind and helpless with only a light fuzz on their backs, teething at around 3 to 4 weeks, at around the same time as their eyes open, and becoming fully furred by 6 weeks. They can climb by 8 weeks, are weaned by 10 weeks and reach sexual maturity in their second year.

Over the course of the 19th century, scientists identified and named several different species of ringtail. Most of them did not stand the test of time, being relegated to subspecies status at best. The one exception is the animal now properly referred to as a cacomistle (Bassariscus sumichrasti) in English. In Spanish, it's the "southern cacomistle" and it's likely that the original word "tlahcomiztle", which is Aztec, was used to describe both species, since they both live in the former territory of the Aztec Empire.

Cacomistle

The two do, after all, look quite similar. The true cacomistle differs from the ringtail in being slightly larger and in having fur with a browner tinge. The rings on the tail are also complete, and fade towards solid black towards the tip. The claws are also nonretractile and the soles of the feet are hairless, which they are not in the ringtail.

Cacomistles live further south than ringtails, inhabiting only the most southerly, tropical, parts of Mexico. From there, they are found in every country of Central America, although only in a comparatively small region of Panama, close to the Costa Rican border. This is a much wetter climate than that inhabited by most ringtails, and the cacomistle is essentially a jungle dweller, living from the lowlands into the central highlands, 2,000 metres (6,600 feet) above sea level. 

Perhaps because of where it lives, the cacomistle has been far less studied than its northern relative but what we do know suggests that, habitat aside, the two species are very similar. Like the ringtail, they are nocturnal, waking after sunset and returning to shelter before the dawn. They spend most of their lives in the mid to upper levels of the forest canopy, which makes them even harder to spot; a study in Costa Rica suggested that the average cacomistle inhabits a 20 hectare (50 acre) area, although this might vary elsewhere, depending on the availability of food.

The diet of cacomistles is also likely similar to that of ringtails, with a fairly even mix of plant and animal matter, although the precise details of their food preferences are not known. They are solitary by inclination, but tolerate others inhabiting parts of their territory and do not typically fight when kept together in zoos. The males in particular are very strong-smelling, which may act as a signal to others of their fitness and sexual status, and they produce a particularly pungent scent from their anal glands. They apparently give birth to single young, rather than a litter, and develop more slowly than the cacomistle.

Ringtails and cacomistles are probably the closest living relatives of the raccoons. Coatis, however, belong to a separate branch within the raccoon family and their closest relatives are not found in Mexico or the US at all, but solely further south. It is to those animals that I will be turning next time.

[Photos by "Robertbody" and Laura Gaudette, from Wikimedia Commons. Cladogram adapted from Koepfli et al. 2018.]