Sunday 18 June 2023

The Raccoon Family: Olingos

Northern olingo
While it's probably fair to say that the members of the raccoon family unique to Latin America are less well-known to those of us in the English-speaking world than are their northern counterparts, the olingos are likely the least well-known of all. Raccoons, coatis, and kinkajous were all scientifically described back in the 18th century - at least in general terms, if not all of the species recognised today. The cacomistle, while known to the Aztecs, didn't reach the scientific literature until 1830, but we have to wait another four decades before anyone European seems to have noticed the olingo.

This was William Gabb, who had been asked by the government of Costa Rica to conduct a three-year biological survey of the Talamanca region, on their eastern border with Panama. He completed the survey in 1876, but died two years later from malaria contracted while on the expedition. His real expertise was in dinosaur fossils so when he discovered a previously unknown species of living mammal, he sent the skull and pelt to Joel Asaph Allen at Harvard. Granted, he was an ornithologist (he would later help to set up the Audubon Society) but he did also have an interest in mammals, and was able to identify the animal as a new member of the raccoon family "as unlike [raccoons and coatis] as these... are unlike each other".

The animal in question was what we now call the northern olingo (Bassaricyon gabbii). Even today, sightings of it are regularly misidentified as kinkajous, so similar are the animals in appearance. Their being nocturnal, and rarely coming down from the trees where they live clearly doesn't help matters, but if you can somehow get a really good look at them the differences do become more obvious. Olingos are smaller than kinkajous; there is some overlap in body length, but at no more than 1.6 kg (3½ lbs) they are always lighter and slimmer. (Not that that's likely to be obvious if it's dashing past you in the treetops at night).

A better guide is the tail, which is not muscular or prehensile in the olingo, and which often has faint raccoon-style rings, something completely missing in the kinkajou. The olingo also has shorter, more brownish fur which is more clearly offset as a paler shade on the belly. There are other minor differences, too, concerning the shape of the skull, teeth, and toes, but these all require close examination. Indeed, while the word "olingo" derives from a native Maya word, it's not obvious that they distinguished it from the kinkajou, and they probably used the same word for both.

The northern olingo is native to Central America, and has three currently recognised subspecies that roughly correspond to one each in Nicaragua, Costa Rica, and western Panama, with the first of those possibly also found across the border in southern Honduras and (less plausibly) even further away in Guatemala. Although they can be found in forests down to sea level, they are more common on mountain slopes above 1,000 metres (3,300 ft.) although the woodlands may become too thin for them above about 1,700 metres (5,600 ft.). In Costa Rica and Nicaragua, they are found predominantly (but not entirely) on the east-facing, Caribbean, side of the mountain range.

We don't know much about their behaviour or lifestyle. They are most often seen in fig trees, and the evidence suggests that fruit is the major component of their diet, although they do also eat such things as flowers from time to time. They seem to be solitary, with one adult male reported to inhabit a home range of 37 hectares (92 acres) - how typical he might have been is, of course, hard to know. Nonetheless, there are a few reports of small groups, one of which cites the presence of six individuals feeding together peacefully in a fig tree, and even playing. That doesn't necessarily mean that they lived together the rest of the time, but perhaps they are not overly territorial and are willing to share particularly bountiful trees.

Eastern lowland olingo

The second species of olingo was named just four years after the first one, in 1880. It has been known under various common names down the years, largely because it kept being split into multiple species and then remerged in different ways. The one that currently bears the original scientific name, because it lives where the original specimen was collected, is the eastern lowland olingo (Bassaricyon alleni). 

Originally found on the eastern slopes of the Andes in Ecuador, it turns out to have a remarkably wide range, being found across much of northern South America east of the Andes, from Colombia in the north to Bolivia in the south, taking in much of the Amazon Basin along the way - although it does not quite reach the Atlantic coast. As the common name suggests, it is generally found at low elevations, but that may largely be because most of its native area is lacking in mountains. At the extreme west of its range, in the Andes of Ecuador and Bolivia, it can be found as high as 2,000 metres (6,600 ft.), which is higher than the northern olingo because the equatorial heat allows forests to stretch further upslope. 

If the northern olingo has not received much study, its southern counterparts have received even less. Physically, the eastern lowland olingo is slightly smaller than the northern species, with fainter rings on the tail and browner fur. The belly is also paler, set off from the fur of the upper body in a distinct line down the flanks... but, really, that's about as far as the differences go. Like the northern species, they mainly eat fruit, with nectar apparently also a common dietary component, but they have also been observed to occasionally eat insects such as moths.

They seem to be mostly solitary but have sometimes been seen travelling in pairs or small groups. One one occasion, a couple of males were seen getting into a fight, possibly over territory or access to females, while at other times small groups have been seen sharing a tree. Otherwise, apart from mothers travelling with their young, one of the few times a pair have been seen together was while they were mating

Speaking of which, because there are some in zoos we know a little more about their breeding habits than we otherwise might. Females come into heat several times a year, and will happily mate with a male over two to three consecutive nights, with each bout lasting up to 68 minutes, suggesting some endurance on the part of her partner. A single pup is born after about 74 days and is able to walk easily by ten weeks although it can take a full five months before they are confident in their climbing abilities. Olingos are also known to make calls to one another, and to scent mark their territory.

Western lowland olingo

The name "eastern lowland olingo" implies the existence of the western lowland olingo (Bassaricyon medius) which lives on the Pacific side of the Andes from Ecuador up to eastern Panama. This was only raised to species level in 2013, having previously been considered a subspecies of one of the others - which one, and whether or not there were other species and/or subspecies is something that changed regularly over the course of the 20th century. This constantly shifting taxonomy, and the fact that it wasn't considered a distinct species for most of its history since it was first named by Oldfield Thomas in 1909 mean that we don't much about it specifically. It's presumably much the same as the others, but it's hard to say when it isn't always obvious which currently accepted species a particular scientist has been studying.

Those who have been reading this blog for a decade or more - or who have gone back to read the older posts - may recognise the significance of this change in 2013. That's because not only is it the year that the western and eastern species of lowland olingo were separated, but in the same paper that showed they were distinct a new, previously unsuspected, species was also identified: the olinguito (Bassaricyon neblina). 


When I wrote my post on the subject, it had been only a few weeks since the official announcement but, since then, the species has been widely accepted. The olinguito lives in the mountainous cloud forests of Colombia and Ecuador, ranging from 1,500 to 2,800 metres (4,900 to 9,200 ft.) in elevation - high enough at the upper end of this range that a non-acclimatised human would start to suffer altitude sickness

The olinguito is the smallest of the olingos, and thus the smallest of all members of the raccoon family, with adults typically weighing less than 1 kg (2.2 lbs). It has richer, thicker fur, than the other species and often has a reddish tinge; the bands on the tail are all but invisible. About the only studies on it since its discovery have been those attempting to confirm exactly where it lives, a question that's obviously important to conservation efforts. Now that we know where this is, we have also dug up some old records that suggest olingos living in those areas make an unusual "whistling" sound not otherwise known and it also turns out that they are sometimes struck by cars, suggesting that they may descend to the ground more often than the other species do.

And that brings me to the end of the raccoon family, with just fourteen species in total. Normally I carry these things on until the end of the year but there simply aren't enough species to do that here without becoming tedious. Which means that, next month, I will be kicking off another, similarly-sized mammal family to take me through the next five months or so. To keep up the theme, it will be one that is not entirely unrelated to the raccoons...

[Photos by Jeremy Gatten, P Asimbaya & L Velásquez, and Mark Gurney, picture by Nancy Halliday, all from Wikimedia Commons. Cladogram adapted from Koepfli et al. 2018.]

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