Prehensile Tails

©Terry R. Thomas/www.nature-track.com

A howler monkey uses its prehensile tail to grasp a trunk for balance.

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Far up a giant Amazon jungle tree a large howler monkey walked among the branches. As it stepped from branch to branch its long tail would wrap around a convenient trunk providing extra stability. The monkey then had use of all four feet for whatever move it wanted to perform next. Its movements through the tree canopy seemed effortless, partly due to its tail.

A tail that functions in this way is called prehensile. In this sense, prehensile means, “capable of grasping.” There are two levels: fully prehensile which means that the tail can be used like a hand to grasp and manipulate objects. Partially prehensile tails are not quite so skilled, but can still be used to allow an animal to dangle from a branch or as an aid in climbing.

The howler monkey we were watching has a fully prehensile tail. It has a hairless pad near the tip that helps in grasping, making the tail nearly like a hand in function. Spider monkeys also have fully prehensile tails, but capuchin monkeys (the “organ grinder monkey”) has only a partially prehensile tail.

Prehensile tails are largely an adaptation of the New World, especially among mammals. Many more New World species have prehensile tails than say, Africa or Asia. One possible reason that has been proposed is that the jungles in the New World are much denser, a situation where having a “fifth hand” could be more useful than in less dense jungles.

While we tend to consider the prehensile tail to belong to the realm of the monkeys, across the animal kingdom many animals have a prehensile or partially prehensile tail. There is even a fish, the seahorse, with a fully prehensile tail that it uses to anchor itself to plants and such.

In the Old World, there are few mammals that have fully prehensile tails. One is the binturong, sometimes called the bearcat, although it is not related to bears or cats. This animal is a member of the carnivore order, one of two carnivores with prehensile tails. The other is the kinkajou, a member of the racoon family, Procyonidae. It lives from Mexico through Brazil.

Pangolins are small insect eating armored mammals, sometimes called scaly anteaters, of the Old World. Eight different species live from West Africa to Southeast Asia. The tree-dwelling species have prehensile tails which they use like New World monkeys.

There are many other mammal species with prehensile or partially prehensile tails. There is the harvest mouse (Old World), tenrecs (Madagascar), opossums (New World), possums (Old World), tree porcupines and anteaters (South America), and some rats all have prehensile tails.

However, mammals are not the only critters with prehensile tails. Most snakes, for example, have the ability to coil their tail (or their entire body—where does a snake’s body start and tail end?) around something.

There are other reptiles with fully prehensile tails as well. Chameleons (Africa and Madagascar) are well-known for using their tails when climbing in trees. Some anoles and some geckos have prehensile tails. The giant (32 inches) Solomon Islands skink is also known as the prehensile-tailed or monkey-tailed skink because its long tail can readily wrap around branches when climbing.

Even some amphibians get into the act with prehensile tails. North American climbing salamanders (eight species from the Pacific coast and the Appalachian Mountains) have prehensile tails for climbing as do several Mexican and Central American species.

It is fascinating to see the wide variety of animals that have adapted to arboreal life through the development of a prehensile tail. Since these species are widely separated genetically and geographically, it is clear that the prehensile tail developed independently many times. It remains one of the great gifts to the animal world. 

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.