Creature Feature: Kinkajou

What has two thumbs, a prehensile tail, and a five inch extrudable tongue? Thiiiiis guy! Kidding. It’s the kinkajou! This adorable fruit-eating tree climber looks a bit like Paris Hilton’s Chihuahua accidentally fell in a taffy pull.

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A kinkajou eats from a balsa flower. [Photo by Rasmus Worsøe Havmøller]
The kinkanjou’s long body helps it to reach far away fruits while its grasping paws and prehensile tail cling to the ends of branches.1 Though the kinkajou doesn’t have an opposable thumb like many other arboreal (tree-dwelling) mammals, they can tightly curl all five of their fingers and toes to grasp small objects and thin branches. They also have a spur, similar to a dog’s dewclaw, that they use to stabilize whatever they are grasping. Once it has a hold of fruit, the kinkajou uses its long tongue to scoop out the fleshy goodness. They have also been observed using their tongues to get nectar from flowers, making kinkajous important for both seed dispersal and pollination!

So kinkajous are really good at eating fruit. Why does that make them interesting? Well, take a look at their evolutionary relatives . . .

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Kinkajous are a member of the Carnivora order – a surprise given that they eat mostly fruit. [Carnviora phylogeny from Wikimedia Commons. Procyonidae phylogeny from Koepfli et al. 2007]
Kinkajous are a member of Procyonid family, which also includes raccoons, coatis, olingos, and ringtails (not the lemur!)2 They are found in closed-canopy forests and range from Central to South America.3 Kinkajous rely on fruit more than any of these close relatives, and when you zoom out a bit you will notice something interesting: nearly all of the kinkajou’s relatives are carnivores. In fact, all of these animals are part of the Carnivora Order (We classify animal taxonomy hierarchically – Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species. I remember using the mnemonic “Daring Kangaroos Play Chess On Fuzzy Green Squares”). Interestingly, carnivore refers to any meat-eating animal however carnivoran refers only to those animals in the Carnivora order, and while many of them are carnivorous, not all of them are! The kinkajou, for example, is frugivorous – meaning they eat mostly fruit.4 After millions of years of evolution selecting for traits that favored eating meat, kinkajous have taken a different evolutionary trajectory.

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Notice the long tongue on this kinkajou, perfect for extracting nectar from flowers! [Photo by Rasmus Worsøe Havmøller]
An evolutionary shift that permits these carnivorans to rely primarily on fruit requires some additional adaptations besides a long tongue or a prehensile tail. Some scientists think dependence on fruit or other similarly distributed resources may play a major in the evolution of sophisticated cognitive skills.5 A frugivorous animal that can remember where productive fruit trees are located and take efficient paths between them should be able to out-compete a competitor lacking those skills. Thus, there is reason to believe kinkajous may have great spatial memory and the ability to plan routes in advance, but empirical evidence to support these hypotheses is still lacking.

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Kinkajous are thought to have the cognitive capacity to navigate between food sources, although this has yet to be empirically tested. [Photo by Rasmus Worsøe Havmøller]
Kinkajous are also nocturnal. As you can imagine, scampering from branch to branch in the dark is probably very difficult! One thing we still don’t really understand is how kinkajous find ripe fruit trees when vision is limited. Perhaps they can smell fruit from great distances, or remember where productive trees are and how to get to them. Kinkajous are known to rub pheromones from their scent glands onto tree branches – it is possible they use these markings as a guide between fruit trees.

Kinkajous are fascinating creatures that in many ways are still a mystery to us. Moving like small cats, they prowl the treetops at night seeking fresh fruit and, for the most part, eluding human attempts to observe them. Their unique ecology and evolutionary history, however, have scientists eager to learn more!

[By: Alexander Vining]


References:

  1. McClearn, D. (1992). Locomotion, posture, and feeding behavior of kinkajous, coatis, and raccoons. Journal of Mammalogy73(2), 245-261.
  2. Koepfli, K. P., Gompper, M. E., Eizirik, E., Ho, C. C., Linden, L., Maldonado, J. E., & Wayne, R. K. (2007). Phylogeny of the Procyonidae (Mammalia: Carnivora): molecules, morphology and the great American interchange. Molecular Phylogenetics and Evolution, 43(3), 1076-1095.
  3. Helgen, K., Kays, R. & Schipper, J. 2016. Potos flavus. The IUCN Red List of Threatened Species 2016: e.T41679A45215631. [http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T41679A45215631.en.]
  4. Kays, R. W. (1999). Food Preferences of Kinkajous (Potos flaws): A Frugivorous Carnivore. Journal of mammalogy80(2), 589-599.
  5. Milton, K. (1981). Distribution patterns of tropical plant foods as an evolutionary stimulus to primate mental development. American Anthropologist83(3), 534-548.

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