23.3a – The Tarsier

Eyes on the prize. (Philippine Tarsier photo by Kok Leng Yeo)

If you break the primate tree into its two most basic divisions, all of the primates we’ve looked at so far — the lemurs, the loris, and the galago — belong to one group, and all of the primates still to come belong to the other. That former group, with the lemurs and such, is called strepsirrhine, and they are the wet-nosed primates. All of the others are in a group called haplorhine, and they are the dry-nosed primates.

There are a few other differences between them besides the dampness of their noses. The lemur group, as with most mammals, can make its own Vitamin C within its body, for example, which means they have no need to include citrus fruit or some other source in their diet; but the dry-nosed primates, which includes humans, lack this ability. To make up for it, the dry-nosed primates have much larger brains in proportion to their bodies.

The divide between these two groups took place approximately 63 million years ago. The first type of animal to separate from the rest of the dry-nosed primates — at least among those that survive today — were the tarsiers. In fact, they are such an old type of dry-nosed primate that even today some scientists debate which of the two groups they belong to.

But what is a tarsier? There are about ten species of tarsier, give or take a few we haven’t fully settled on yet, and they are small, strange-looking primates that look either very cute or nightmarishly alien, depending on your frame of mind.

The reason for this is their enormous eyes. I don’t want you to think I’m being hyperbolic when I say “enormous”. In absolute terms, certainly, a small monkey can only have eyes that are so big, but the tarsier stretches the bounds of relativity. Each of its eyes — not both together, but each separate — is as big as the animal’s brain. These are the largest eyes relative to body size in the entire mammal world. They look like tiny, big-eyed gremlins.

But you can’t judge a book by its cover, I can hear you saying. Just because it looks a little strange doesn’t mean it’s anything to be afraid of, right? It’s basically a tiny monkey, isn’t it? And tiny monkeys are cute and curious and wonderful, aren’t they?

… aren’t they? (Philippine Tarsier photo by Serafin “Jun” Ramos, Jr)

The first thing to remember about a tarsier is that no, it is not a monkey at all. It is an early, primitive form of the type of primate that eventually produced monkeys. One of the key differences, besides the outward appearance, is that the tarsiers are the only one hundred percent carnivorous primates alive in the world today. They don’t seek out fruit or vegetable matter. They eat nothing but the crunchy, squirming flesh of other living beings, including snakes, bats, birds, and lots of insects. Which I suppose means we’re back to them being essentially gremlins.

But in truth they are shy creatures, and certainly not dangerous. They’re nocturnal and live in and around the jungle islands of southeast Asia, such as the Philippines, Indonesia, and Borneo. Many of them are threatened or endangered due to habitat loss, human hunting, and predation by feral cats.

Sometimes they are kept as pets by well-meaning humans. Keeping a wild animal as a pet is almost never a good idea, but with the tarsier it’s an even worse plan. The tarsier is one of the rare animals that does significantly worse in captivity than it does living in the wild. In the wild, with an abundant food supply and a thick jungle in which to move around, a tarsier can expect to live for 24 years. In captivity, they last only 12 years at most, and can die as young as two years old. In human terms, this is the equivalent of taking a person who can expect to live to the age of 72 and placing him in an environment where he may fade away and die by the age of 6. That’s a poor thing to do to an animal, no matter how cute they look.

Some tarsiers are even known to commit suicide in captivity. They don’t actually kill themselves on purpose, but the stress of lights, unfamiliar noises, and human handling can seriously frighten a shy tarsier, and they will sometimes react to this stress by smacking their own heads against objects in their enclosure. Since they have fairly thin skulls, this can cause death.

Fortunately it’s illegal to sell or trade many types of tarsiers. Conservation efforts in some countries seek to establish safe refuges for the animals, but their future remains uncertain.

Tarsier distribution

Tarsier distribution

23.1c – The Aye-Aye

A superstition in the night. (Photo by Frank Vassen)

In Madagascar, a land of strange creatures, one of the strangest of all comes creeping out after dark. Nearly two feet long from head to tail with another two feet of bushy tail behind it, this creature’s large, red eyes peer out through the leaves of a tree. Soon you see its fingers — long, thin, alien, the things of nightmares. With a tap-tap-tapping of its thinnest, almost skeletal finger on the tree, it comes toward you.

The aye-aye is an oddity. Once thought extinct, it was rediscovered in the 1950s and still roams the forests of eastern Madagascar. We call it a lemur, but in truth we aren’t one hundred percent certain what it really is.

The aye-aye, if it is a lemur, is the world’s largest nocturnal primate. The creepy thin hands it sports are a unique evolutionary adaptation that allows it to reach a food source untouched by other animals on the island — insect larvae living beneath the bark of trees, the same food source used by woodpeckers in other parts of the world.

While the woodpecker bores holes in trees with its beak, the aye-aye taps its incredibly thin middle finger up to eight times per second along the bark as it moves. It is able to hear the echoes of its tapping and determine where there are hollow spaces. The creature then gnaws a hole in the bark with its long teeth and inserts its longest finger into the hole to pull out any grubs or other insects living within.

Its teeth grow constantly throughout its life, exactly like a rodent’s teeth, and this prompted early scientists to classify the aye-aye as a rodent. In addition, it climbs trees in a very similar manner to a squirrel, and has some anatomical similarities to rodents as well. Is it possible that some lone species of rodent somehow crossed to Madagascar and evolved into something so strange?

It is possible, but scientists now believe the aye-aye is a primate. What sort of primate is up for debate, but current general consensus is that it is a unique type of lemur, distantly related to the others, highly evolved and specialized to take advantage of a certain food source that none of the other lemurs can access. But in truth, we’re only making educated guesses. It is the only primate known to use echolocation, and we don’t know for certain how it fits into the classification scheme.

The native people of Madagascar don’t know either, and in fact they are just as creeped out by the long fingers and red eyes as we are. The aye-aye also has a somewhat fearless nature, and has been known to stroll into villages or approach humans in the forest. People are afraid of them.

Looking at this, I’m not entirely sure we can blame them. (Image by Joseph Wolf)

In addition to natural fear, the native people believe the aye-aye is evil, a harbinger of death. It is claimed that if an aye-aye points his thinnest tapping finger at you, it has marked you for death. Some believe that the creatures can break into houses in the night and kill a man by piercing the heart with that same long, thin finger. For these reasons, the aye-aye is traditionally killed on sight by natives.

Combined with deforestation, this means that the creature is considered near-threatened, and a second species of aye-aye is believed to have gone extinct within the past thousand years. And there is nothing inherently evil about them, no more so than any other animal and less perhaps than some. They look rather disturbing compared to other animals we are used to, but they are harmless. They eat insects, and will occasionally steal fruit from villages; the rest is superstition brought on by the strange appearance they have evolved to reach their food.

However, even without the superstition, aye-ayes can damage local crops, and are killed by farmers for this reason. Madagascar is not a wealthy nation, and many of its people are poor. Any threat to local food supplies, whether in the field or through thievery from storage areas at night, prompts unfortunate but understandable reactions.

And if you’re wondering where the name “aye-aye” came from, no one quite knows that either, but it’s not because it was named by affirmative sailors. It might refer to a sound that the animal makes; it might refer to the sound the natives make when they see it and run away; or it might come from “heh-heh”, which in a Malagasy language means, simply and appropriately, “I do not know”.

Aye-aye distribution

23.1b – The Dwarf Lemurs

The littlest lemurs. (Gerp’s mouse lemur photo by Blanchard Randrianambinina)

Though all of the lemurs found on Madagascar are a little on the small side — there is, after all, no evolutionary pressure to grow large when you have no competition and live on an island with limited resources — the dwarf lemur family contains the smallest members, and in fact they are the very smallest primates in the world.

There are 31 different species of dwarf lemurs, though many of them are known rather as mouse lemurs. Even the largest is less than a foot tall, and they have exceptionally soft hair. All of the various dwarf lemurs spend nearly their entire lives in trees, where they are agile and comfortable; on the ground they hop on their hind legs like tiny kangaroos, and become easier targets for predators.

As a nocturnal species, dwarf lemurs are not generally as social as most other primates. They tend to live alone or in pairs, though some of them form big sleeping groups during the day so they can snuggle up together. Some of them store fat in their tails, so if you see a dwarf lemur with a big chubby tail, you know it’s well-fed. During dry times and times of food shortages, many of the dwarf lemurs enter a torpor, in which they sit around and use very little external or internal energy to help them survive until food returns.

One of them, the fat-tailed dwarf lemur, enters a full hibernation during the dry season. It is the only tropical mammal and the only primate known to hibernate (discounting, of course, human teenagers during Christmas break). This is interesting because most animals hibernate because of the cold; but even during the dry winter, Madagascar is still very warm, and the fat-tailed dwarf lemur’s body temperature tends to go up and down depending on the weather outside, even while it’s hibernating.

“If your tail was this fat, you’d be sleepy too.” (Fat-tailed dwarf lemur photo by Petra Lahann)

The mouse lemurs are even smaller than the other types of dwarf lemurs. For a long time we didn’t know a lot about mouse lemurs for the simple reason that we didn’t know how many there were. All of the various mouse lemurs look similar to each other, so for a long time we thought there was only one kind. But in the last 35 years we have determined that even though they look alike, there are actually 19 different species of mouse lemur scattered around Madagascar, and perhaps more that we haven’t found yet. One of them, Gerp’s mouse lemur, was only discovered this very year, in 2012.

The smallest primate in the entire world is Madame Berthe’s mouse lemur. It averages only about three and a half inches long, and weighs only an ounce. It can be found only in one small national park on the western coast of Madagascar, and its interesting name comes from Madame Berthe Rakotosamimanana, a woman from Madagascar who founded the Group d’Etudes et de Recherche des Primates (Group for the Study and Research of Primates). Be thankful they didn’t use her full name for the species.

There are no freely-available photos of this lovely small primate, but if you are so inclined, you should click through to this photo to see a baby Madame Berthe’s mouse lemur, which I think you’ll agree is about the most adorable it is possible for a primate to be.

One of the most interesting things about the mouse lemurs is that they all somehow agree to get along and not bother one another. An extensive study was done on Madame Berthe’s mouse lemur and the gray mouse lemur, which live close to one another. They eat the same things and live in the same type of habitat. The gray mouse lemur is larger, stronger, more adaptable, and better able to survive; if it wanted, it could easily push the smaller mouse lemur out, perhaps to extinction. But it does not. The gray mouse lemur’s territory goes right up to the edge of the territory used by Madame Berthe’s mouse lemur, and there it stops.

Why? We don’t know. There are very few animals in the world that share the same resources and the same habitats without one suffering from the presence of the other. But the mouse lemurs, for whatever reason, are content to live with what they have, in the area they call their own, and not to bother their neighbours. If only some of the larger primates could be so reasonable.

“Hi there, neighbour.” (Brown mouse lemur photo by Frank Vassen)

In fact, some dwarf lemurs and mouse lemurs have territories so small that they can only be found around the region of a single village. They are blips on the map, but they are there, living their tiny lemur lives.

But like many lemurs, they are threatened by deforestation across the island. It is entirely possible, given the miniscule territories of some recently discovered mouse lemurs, that entire species of these diminutive primates have already been destroyed before they were ever discovered.

Dwarf Lemur distribution

20.1d – The Zebra

What’s black and white and wild all over? (Photo by Paul Maritz)

The zebra (pronounced either ZEB-ra or ZEE-bra, either is fine) is the only type of modern horse that has never been widely domesticated, and is also the most visually striking of the horses because of its distinctive black-and-white striped hair. But the word zebra itself is not actually an indication of a closely related group of animals.

There are three species of zebra — the plains zebra, which is most common, the mountain zebra, and Grevy’s zebra. The plains and mountain zebras are closely related to each other and also are distant cousins of the horse; but Grevy’s zebra is actually more closely related to the asses than to the other zebras.

The only thing that makes them zebras is that they all have the black and white stripes, which would lead one to believe that they were the same type of animal, but they’re not. How then did they all end up with the stripes?

We don’t actually know. It’s possible that stripes evolved twice in the horse family, but that’s unlikely. The most probable answer is that the common ancestor of the entire horse family had stripes, but the horse and the asses went on to lose their stripes because they weren’t useful in the new environments they moved to. The three zebras, even though they aren’t all closely related, are the ones who kept the stripes. But we don’t know for sure if that’s true.

What about those stripes, anyway? They’re so striking and fascinating to us; why do zebras have them? First, you should understand that the common and understandable idea that zebras are white with black stripes is incorrect. They actually have black bodies, and it’s the white parts that are the stripes.

When you look at a zebra you might think that such flashy stripes wouldn’t be much good for camouflage, but you’d be wrong. For one, some zebras live in brushy or forested areas, where the stripe pattern blends well with branches. For another, the zebra’s most common predators are believed to be colour-blind, so the grass looks the same colour as the stripes to them.

But some scientists don’t think the stripes are really about camouflage at all. One idea is that a bunch of zebras together sort of blend into a stripey mass, which might serve to confuse predators and keep them from being able to separate one animal out from the herd. Another idea is that zebras might be able to identify each other socially from the stripes, since no two zebras have exactly the same pattern, but there’s no real evidence that zebras can view each other as individuals outside of family groups.

Yet another theory is that the stripes help keep zebras safe from biting African flies. Experiments have shown that disruptive stripes like that can confuse the visual system of flies and make them less likely to land. This might also explain why zebras in Africa, where there are many harmful flies, have stripes, while the other members of the horse family lost theirs; however, zebras do still suffer from flies, and this notion doesn’t explain why the African wild ass has no stripes.

Otherwise the plains zebra and the mountain zebra are a lot like a horse, and Grevy’s zebra is a lot like an ass. The horse-like zebras roam typically in small herds with one male and several females and their young offspring, with non-dominant males forming small bachelor herds or wandering alone. The ass-like zebra only forms temporary herds.

Grevy’s Zebra: commitment issues? (Photo by Rainbirder)

People have been trying off and on to domesticate zebras for hundreds of years. Some zebras have been tamed and ridden by humans, but actual domestication hasn’t happened, for zebras are in general harder to teach and more easily frightened, perhaps because they come from a land of lions and cheetahs, leopards and African wild dogs, hyenas and crocodiles.

The mountain zebra and Grevy’s zebra are both threatened and found only in small pockets of Africa. Zebras have long been hunted by humans, both for meat and because while their stripes may be good against predators, they also make for attractive skins for greedy humans. They have also been forced to compete with livestock and agriculture.

19.2a – The Bilby

The great spiral of life. (Photo by Dcoetzee)

In the article earlier this week about the order Peramelemorphia, I said that there are two species of bilby. I regret to inform you that this is probably no longer the case.

The lesser bilby, a small rabbit-like marsupial that hopped about the deserts of central Australia, was only just discovered in 1887, was seen rarely by scientists, and hasn’t been spotted at all since 1931. In the 1950s the animal was declared extinct. But where the mysteries of the great Australian Outback are concerned, that is not of course the end of the story.

Native tribes in Australia, which know more about the desert areas of that country than any scientist, continued to describe the species into the 1960s when at last even they stopped seeing any. In 1967 a lesser bilby skull was found beneath an eagle’s nest in the desert, but the bones may have been as many as 15 years old.

This was the last reported find of anything to do with the lesser bilby. We believe it died out because of that scourge of the great southern continent, the invasive rabbits, cats, and foxes.

But the Australian desert is an enormous place, and both little studied and even less understood at times. It is still possible that the lesser bilby survives somewhere out there, unseen by human eyes. Even if so, however, its numbers would be small and the invasive animals keep coming, meaning that the end, if not come already 50 years ago, is surely near.

But the greater bilby, now sometimes simply called the bilby because it’s the only one we know for sure is left, still roams the deserts of west-central Australia. It is a threatened species for the same reasons, but it has one advantage that has kept it alive in the face of invasive predators — the greater bilby digs its burrows in a spiral pattern rather than a straight hole, and this makes it much harder for cats or foxes to get them.

All the same this nocturnal creature’s population is on the decline. Looking something like a bandicoot with floppy ears and a longer tail, the greater bilby is about the size of a rabbit. As noted above, they can burrow with the best of them, unlike their bandicoot cousins. A bilby digs several of those spiraled burrows in its territory, so that it is never far from one if it feels threatened. Like all digging marsupials, the bilby has a pouch that faces backward so dirt doesn’t get in it.

Numerous conservation efforts are underway to keep the dwindling bilbies alive, including captive breeding and reintroduction to former living areas, particularly areas that have now been made relatively predator-free.

There is also a push to replace the Easter Bunny in Australia with the delightfully named Easter Bilby. Chocolate Easter Bilbies are sold at Easter, and sometimes a portion of the proceeds go toward bilby conservation efforts. I think it’s a wonderful idea, because honestly, Australia and all its many marsupials have had quite enough of rabbits already. Celebrating a holiday that uses a rabbit as its mascot just doesn’t seem right at all.

Bilby distribution.

13.1b – The European Rabbit

Be vewy vewy quiet. This threatened species is taking over the world. (Photo by Norrie Adamson)

When most people in the world think about a rabbit, the European rabbit is the one they’re thinking about, whether they know it or not. It has the interesting and almost paradoxical distinction of being an animal that is considered near-threatened even though there are literally hundreds upon hundreds of millions of them in the world.

European rabbits are naturally found in Spain, Portugal, and the northwestern corner of Africa. When Phoenicians first visited the area, they saw the rabbits, which looked similar to the native hyraxes they knew in Africa. For this reason they named the land i-shapan-im, “the land of the hyraxes”. From this name eventually came the Latin Hispania, from which comes the English word, Spain.

The European rabbit is the only species of rabbit that humans have ever domesticated on a large scale. Almost every single pet rabbit in the world is derived originally from European rabbits, even though, as with dogs and cats, many different breeds have been created. We have taken them with us almost everywhere we’ve gone, and so you can find European rabbits almost everywhere, especially in places where they aren’t wanted.

Australia, as we’ve noted, has several hundred thousand European rabbits destroying their country, but that’s not all of it. There are European rabbits devastating New Zealand as well. There are 40 million European rabbits in England, where they are an invasive species. And they are many other places besides. They are one of the few animals that we call pets (because they are cute and fuzzy), pests (because they eat everything we try to grow), and food (because they are delicious) all at the same time. The world is filled with European rabbits.

Adorably tasty, or tastefully adorable? (Photo by T. Voekler)

Which is why it seems so odd that they are considered a near-threatened species, but there is a crucial distinction that must be made. All of our pets are domesticated rabbits, and all of the invasive rabbits in Australia and England and elsewhere are feral rabbits, which means that they were once domesticated but escaped and live on their own. A feral rabbit is not the same as a wild rabbit. They may have similar behaviours, but feral animals are affected by their domestication, and this is passed on to generations born later as well. In most cases, a feral animal is not a natural part of the environment it lives in.

For this reason, when we speak of the European rabbit as near-threatened, we refer only to the wild European rabbit, those rabbits whose ancestors have never lived with humans. A wild animal is a wholly different creature than a feral one.

That said, you may be surprised to learn that we don’t know an awful lot about wild rabbits. We know quite a bit about the tame ones, of course, and we know a lot about the pesky feral rabbits, but wild rabbits are shy, frightful, and spend most of their time either underground or in dense brush, so it’s hard to get a sense of them.

Almost everything we know about wild rabbits comes from the work of naturalist Ronald Lockley, who studied wild rabbits closely in the 1960s and published a book, The Private Life of Rabbits, which would be an inspiration for the novel Watership Down.

What we know from this work and other smaller studies since is that European rabbits in the wild are very social animals. They live in underground colonies called warrens. Within each warren, rabbits break up into groups of two to ten animals that live closely together.

Breeding is one of the most important parts of a wild rabbit’s life — because they are so small and tasty, rabbits ensure the survival of their species by making incredible numbers of babies. Each wild rabbit group has a dominant male and a dominant female. The dominant male gets to mate with just about whoever he wants to, while the other rabbits form mostly monogamous mating pairs.

The social ladder is very important for wild rabbits, and your standing on it depends on a variety of factors. These include but are not limited to: the size of territory you patrol; the number of females who visit you; the amount of time females let you sit near them; the number of friends you have; and the distance you travel every day. Your social credit can also improve based on the number of non-friend rabbits you fight with.

For this reason wild male rabbits will duke it out almost at the drop of a hat. The common method of challenge is for one rabbit to urinate on another, which says, “You are my territory.” Regardless of which two rabbits are involved in this, it immediately leads to a fight. Rabbits may be timid when it comes to dealing with other animals, but when they are alone they are anything but. Two fighting rabbits will beat each other with their large feet and will bite and claw without mercy. Many rabbits die from fights like this.

Once the social order is sorted out, rabbits breed, and they do it as often as possible. A female can produce a litter of two to twelve bunnies in about a month, and in good conditions two rabbits can make 30 or 40 offspring per year. Wild European rabbit males appear to get along well with their children, but this may only be because they want more friends, which means more social standing.

When ready to breed, European rabbits will emit a particular odour from a gland in their chins, of all places. This is known as chinning. If you are ever reincarnated as a wild rabbit and another rabbit starts rubbing its chin on you, well, now you’ll know what’s up.

European rabbits take shelter during the day, and only typically emerge to feed on fields or in gardens at dusk and again at dawn. They can run much faster than a person, and will immediately bound away on their big legs at the first sign of danger, which they will sense coming easily because of their enormous ears.

Though you can find a European rabbit just about anywhere these days, the wild European rabbits of the Iberian peninsula are on the decline. With so much urbanization and agricultural development there is not a lot of room left for the rabbits, and when they come into our fields to eat our crops we tend to take it badly. In addition to hunting the wild rabbits as pests, we also hunt them for food. Rabbits in the wild are also preyed on by anything that likes meat, from birds of prey to wild cats to tiny but ferocious weasels. In the ultimate insult, even squirrels will kill and eat a rabbit if it is injured or otherwise unable to run away.