Euplerids: Madagascar's Top Mammalian Carnivore

The native mammalian carnivores of Madagascar are mostly obscure to those of us in the West. The one possible exception, thanks to the Madagascar animated film franchise, is the fossa (Cryptoprocta ferox). Often spelt with a single 's', especially in more modern sources, and typically pronounced "foosa", this is the largest and most potentially dangerous of all the island's native mammalian predators.

Having said which, it's not especially big compared with predators elsewhere. There is little need to be a large carnivore when the island does not have, for example, any native antelopes. On average, they are about 75 cm (30 inches) in body length, not counting a cat-like tail that adds about the same length again. Adult females weigh around 6 kg (13 lbs), while the largest males can reach 8.5 kg (19 lbs), about the same as a West Highland terrier. 

Exactly where they fit within the mammalian family tree was long a source of confusion, given a mix of features resembling a range of other animals. When English zoologist Edward Turner Bennett first described the animal in 1833, he considered it to be a type of unusually large civet. So it remained for a hundred until it was moved to the cats in the 1930s, back to the civets in the 1940s, and then to the mongooses in the 1990s. Over the next ten years or so, arguments continued back and forth between all three of these options until genetic studies finally settled the matter in 2003. 

Covid and the Landscape of Fear

Left to their own devices, animals will wander about wherever there is food or other useful resources to be found. They would be limited only by the physical properties of their landscape, such as the inability to cross a wide river or the presence of a barren mountain range. Reality, of course, is never quite this simple.

The earliest use of the term "landscape of fear" that I could find on a quick search referred to a study about how female college students felt while walking particular routes alone after dark. Put in this context, one can well understand why people don't necessarily pick the simplest or most direct route to their objective, and why there are certain places one might simply wish to avoid altogether.

Black Bears and the Uncertain Apex

The concept of the food pyramid is a central one in ecology. The idea is that since consumption cannot ever be 100% efficient, every type of animal must necessarily be less common than whatever it is that it feed on, at least in terms of its total biomass. Plants are more common than herbivores are more common than small carnivores are more common than larger carnivores.

The actual picture is more complicated than this. Many "carnivores" are at least partly omnivorous, and they often eat large herbivores more regularly than they eat small carnivores. Plus, we also need to consider the detritivores and parasites. But the general pattern holds, and at the top of the pyramid, we find the apex predators. 

It's possible to argue as to what exactly constitutes an apex predator. The general idea, however, is that they feed on other animals without being preyed upon themselves. At least among terrestrial mammals, an average body mass of more than about 15 kg (33 lbs) is generally about enough that predators need to manage their own population (through competition, territoriality, infanticide, etc.) rather than having to worry about something larger and scarier managing it for them. 

Running Hyenas of Greece

Chasmaporthetes

Mentioning a "hyena" today likely brings to mind the image of a muscular, aggressive, scavenging creature, probably with a spotted coat. This, the spotted hyena (Crocuta crocuta), is, however, only one of three species alive today, with the two lesser-known ones being smaller and less aggressive. In fact, the hyena family includes a fourth living species as well, although this isn't always referred to as a "hyena" because it's really only dangerous to termites and can't crack bone like "true" hyenas can.

Four living species isn't very many for a family of mammals but, like many other such small groups, there is a long fossil history that includes a great many extinct forms. These varied in form even more than the living species do. At one extreme are animals larger and stronger even than the living spotted hyena, while at the other (all living very early on) are small tree-climbing animals that looked more like civets. 

Somewhere in between are the "running hyenas".

The Family Life of a Spectral Bat

It may not be Halloween just yet, but it is October, so that's as good a time as any to talk about an animal that goes by the name of the spectral bat (Vampyrum spectrum).

You might think from the scientific name that this is a close relative of the vampire bat but, while it does belong in the same family, vampire bats are a side-branch of that family thought to have diverged from the main branch around 50 million years ago. Its closest relative may be the far less fearsomely named "big-eared woolly bat" (Chrotopterus auritus), with which it shares some of its unusual feeding habits. 

Delphinids: Killer Whales

Orca / killer whale

The dolphin family is scientifically defined as including all the species more closely related to the common dolphin than they are to porpoises. The great majority are what we'd normally think of as "dolphins" but four species are so much larger that, instead, we tend to call them "whales". Three, including the two species of pilot whale, are of roughly similar size to each other, but the fourth is noticeably larger still.

It's the biggest "dolphin" of all: the orca or killer whale (Orcinus orca).

That it is a dolphin has never been seriously doubted from a scientific perspective. It is one of just three species of dolphin to be listed as such in the first catalogue of scientific names in 1758 - and one of the other two is a porpoise, and so has since been moved elsewhere. On the other hand, it has been recognised as belonging to a distinct subfamily with the dolphins since 1846, and modern genetic studies confirm that its ancestors diverged from those of most other dolphins unusually early. 

Oligocene (Pt 16): The First Monkeys in South America

A modern South American monkey

Much like the rodents, the presence of monkeys in South America has long been a puzzle. We know that monkeys evolved in Africa and that the monkeys still living in the Old World share a common ancestor distinct from, but related to, the common ancestor of the American sort. Genetic evidence shows that the split between the two lineages, which must have happened in Africa, happened a very long time ago. At some point then, early monkeys from what we now call the 'New World' group must have crossed the Atlantic, likely rafting on a floating patch of vegetation.

The Atlantic was narrower then than it was now, and ocean currents were different, but it's still a remarkable feat. It may also have been a lucky escape, since the African relatives of this first American migrant died out not long after, perhaps outcompeted by the ancestors of today's langurs, baboons, macaques, and apes. In South America, however, its descendants got almost free rein, diversifying into the five families we have today.

Bast, Sekhmet, and the Egyptian Hyena-cats

Megistotherium, a Miocene hyena-cat

The majority of the land-based mammalian predators we are familiar with today belong to the order Carnivora. This is a diverse order, including such mammal families as the cats, bears, dogs, weasels, and seals. In fact, if we ignore the cetaceans and a few kinds of marsupial, they are the only large carnivorous mammals alive. But, as so often, this was not always the case, and they once shared the world with at least three other orders of predatory placental mammal (plus some marsupials far more fearsome than any Tasmanian devil). 

Two of these orders died out relatively early on, but one of them survived for much longer, producing multiple diverse species that lived across Eurasia, North America, and Africa. These were the hyaenodonts, named for Hyaenodon itself, first identified from a fossil all the way back in 1838. With so many species, they must have been successful in their day, but their numbers declined until the last two species died out in Africa and India around 9 million years ago, perhaps due to competition from the carnivorans, perhaps due to long-term climate change. Or, more likely, both.

I Ain't Afraid of No Owls

Northern bat

There is no particular reason why bats should be nocturnal. True, nocturnality has many advantages, but so does daytime activity; the real question is why so few bats fly during the day. I looked at this last year, where I mentioned that one of the main theories is that since birds evolved flight before bats did, the bats originally flew at night so that daytime predators, such as hawks and eagles, didn't try to eat them.

If so, it may be an effective strategy, since there isn't very much that eats bats on a regular basis. That isn't to say that there isn't anything, however. The bat hawk is, as its name implies, probably the single most specialised bat predator, but studies in Africa have shown that hobbies (which overwinter there), Wahlberg's eagles, and African goshawks also attack bats with some frequency, and they're probably not alone. In this part of the world, bats, as one might expect, take measures to reduce their risk of attack. Flying in large flocks may help, but it's also known, for example, that they avoid flying on moonlit nights, and, when they have to, they don't fly above the trees as they normally would, keeping themselves out of view.

Cheetahs and Wild Sheep

The cheetah (Acinonyx jubatus) is surely one of the most familiar of African animals, due in large part to their prominence in wildlife documentaries such as Cheetah Family & Me. They are charismatic, distinctive, and not especially rare or difficult to find. Unlike, say, tigers, they are not internationally listed as an endangered species, although their population has declined rapidly enough over the last few decades that they do qualify for the lesser rating of "threatened" or "vulnerable" species. 

This does, however, disguise some significant regional variation.

How we should divide the cheetah into subspecies is not absolutely clear. From at least the 1970s, five subspecies were recognised, Two of those were merged in 2017, on the grounds that the East African form could not be reliably separated from its southern relative genetically. Even then, cheetahs have so little genetic variation across their range - due to an apparent population bottleneck when they almost died out at the end of the Last Ice Age - that support for the existence of two of the other subspecies remains a little shaky. Still, four subspecies is, for the time being, the general consensus.

The Life and Habits of the Father of Cats

Today, all large land-dwelling carnivorous placental mammals belong to a single group named, appropriately enough, the Carnivora. This includes all the cats, dogs, bears, badgers, and many others besides, and it has long been clear that they are a genuine biological group, all more closely related to each other than to anything else. Indeed, the similarities between these animals are sufficient that, even though the current name only dates from 1821, it's essentially identical to the "Ferae" order first described back in the 18th century.

Even if we look at the fossil record, we find that for millions of years, the great majority of such animals were also members of the Carnivora even if, in some cases, their specific family no longer exists. The great majority, but not all. In 1875, American palaeontologist Edward Drinker Cope coined the term "creodont" for a collection of early carnivorous mammals that lacked the key defining features of the carnivorans. His original definition was relatively narrow, but over the next few decades it was expanded until, in 1909, it came to include essentially all of the large land-dwelling carnivorous placentals that weren't carnivorans.

Decline of the Sea Otters

Sea otters (Enhydra lutris) are an endangered species, native to the coasts of the northern Pacific from Japan to California. I've discussed them in detail before, but suffice it to say here that they are remarkable creatures, able to survive without setting foot on land, digging no dens as other otters do, and even giving birth at sea. They also have the densest fur of any mammal, making it especially valuable.

Which, of course, explains how they became an endangered species in the first place.

Humans have been hunting sea otters for their fur for many centuries, but for much of history, this was small scale, with the local tribes being unable to make any lasting dent in their numbers even if they had wished to. Estimates for the worldwide population of sea otters prior to the 18th century are naturally difficult to come by, but it may have been as high as 300,000. The herald of coming doom came in 1741.

Benefits of a Deadly Predator

A basic concept in ecology is that of the trophic level, a concept that lines up life forms by where they sit in the food chain. Plants are at the bottom level, taking energy directly from the sun, then the next level up are the herbivores, which eat the plants. Above that we have primary predators eating the herbivores, and then secondary predators eating the primary ones. Because the transfer of energy is never perfect, each level will be smaller than the one below it, with fewer individual life forms in it, thus forming a pyramidal pattern.

The reality is more complex than this. Secondary predators also eat herbivores, omnivores are common, really large herbivores aren't likely to be eaten by anything, there may be more than two steps in the chain of carnivores, and we can't forget the detritivores and fungi. And so on. So what we actually have is a "trophic web", a complicated set of interactions where some animals don't fit neatly into a single level on the pyramid. Nonetheless, that doesn't make the basic idea useless and one of the concepts it leads to is the apex predator - the large carnivores that have no predators of their own (at least as adults).

The Lion Stalks Tonight

In the jungle, the mighty jungle, the lion probably does not sleep tonight.

The main reason for this is that lions don't really live in the jungle. Their primary habitat is savannah and open grasslands and while they can be found found in dry woodland (especially in India) they aren't found in the tropical rainforests that we typically associate with the word "jungle". Indeed, a map of Africa showing where you can find lions would have a very noticeable gap in the middle where the Congo jungle is - along, of course, with blank spaces over the harsher deserts. The idea of lions living in dense jungle probably owes more to Tarzan than reality.

Before Owls Ate Mice

Palaeoglaux

Most bird species are diurnal. Doubtless, if you're flying about and don't have sonar, as bats do, it helps to be able to see where you're going. Nonetheless, there are many exceptions to this general rule, and none are more obviously so than the owls.

There are well over 200 living species of owl currently recognised, ranging in size from the mighty Eurasian eagle-owl (Bubo bubo) with a wingspan of up to 180 cm (6 feet) down to the tiny elf owl (Micrathene whitneyi) with a wingspan of just 27 cm (10 inches). They are grouped into two closely related families; the great majority of species belong in the Strigidae family, with just 20 assigned to the barn owl family, the Tytonidae. While there are some internal differences between the two, the most visible in the living animal is that barn owls, unlike regular owls, have distinctive heart-shaped faces.

Both families have been around rather longer than most mammal families have, with fossil representatives dating back to at least the Early Oligocene, around 35 million years ago. The two families are, however, rather like pigs and peccaries, each others' closest relatives, together forming the order Strigiformes. Since few people would deny that a barn owl is, in fact, an owl, it's this order that's really the scientific counterpart of our everyday understanding of the word.

The Cat Family: Felidae

It is sometimes said, perhaps only half-jokingly, that the growth of the internet has been largely driven by two things: pornography and pictures of cats. I can't do much about the first of those here, but cats are a different matter.

In fact, the reason that I haven't looked at cats so far in my annual surveys of mammal families is precisely because, if there's one group of mammals that has substantial coverage on the internet already, it's cats. Lions, leopards, and so on are also amongst the most popular of subjects for TV wildlife documentaries, and it's hard to see that I have much to add. But, nonetheless, and while I have, of course, covered cats before in individual posts, exploring the family is a gap that I eventually had to fill. So here we go.

Compared with some, more diverse, mammal families, members of the cat family, Felidae, are all readily identifiable as such. Cats have short faces, lacking the long snout of dogs, with large eyes and ears, and prominent whiskers. Their bodies are generally sleek, usually (although not always) with long tails, and they have muscular limbs and sharp claws. Indeed, apart from size and coat colour, most species of cat are remarkably similar in physical appearance. If you removed the skins of a lion and a tiger, only a real expert would have any chance of telling them apart.

Murderous Whales of the Eocene Oceans

The relationships between what animals eat can be thought of as a pyramid. At the bottom are plants, which are eaten by herbivores, which are eaten by carnivores, which are eaten by larger carnivores. The reality is much more complex, and is more accurately thought of as a web (omnivores exist, large carnivores also eat herbivores, etc.), but the general principle is broadly true. In particular, the further up the ladder you go, the fewer animals there are, since the transfer of energy from one level to the next can never be 100% perfect.

At the top of the pyramid are the "apex predators". These are the carnivores that have no predators of their own, that are able to feed without fear of being eaten themselves. Again, the reality is more complex - an adult of one apex predator might occasionally kill and eat the young of a different kind, for instance. And, of course, everything gets eaten by worms (or whatever) once they're dead. Nonetheless, really big scary predators clearly do exist, even if, by their nature, they aren't very common.

Gerbil versus Rattlesnake

Sidewinder

Deserts are harsh environments, and living in them poses animals a number of problems, not least of which are daytime heat and an absence of water. In order to survive in such a place, animals need to evolve suitable adaptations - extremely efficient kidneys to reduce water loss are one such example.

But the thing about deserts is that, while there are some geographic differences between them, the challenges of living in one are at least broadly similar regardless of which desert it happens to be. And while, say, the world's seas are all connected, the deserts aren't. So animals, including mammals, have had to evolve means of surviving in them several times over, re-developing the necessary features each time they encounter a new one.

Bats That Eat Fish

Greater bulldog bat

With over 1,300 different species of bat known, it shouldn't really be surprising that there's a wide range of different dietary habits among them. Of course, a lot of that is on a fine scale, as I discussed just last month, but there are more significant differences in the kinds of things that bats feed upon. Insects, fruit, nectar, even blood all form the core diet of at least some kinds of bat.

One of the more unlikey food sources, however, is fish. Yet, when you think about it, fish is a really common food source for birds - there are a huge number of bird species that feed primarily on fish, including seagulls, kingfishers, and ospreys, among many others. Clearly, there's no inherent reason why a flying mammal couldn't eat fish, yet very few of them do.

As a recent review makes clear, however, "very few" is not "none".

Modified Munchies of Many Mouse-eared Myotises

In the modern system of taxonomy for the classification of living things, a genus is  group of closely related species. It is the lowest mandatory level of classification, apart from 'species' itself, and forms the first half of a creature's scientific name. Thus, Panthera, for example, is the genus containing lions, tigers, leopards, snow leopards, and jaguars.

As such, we'd typically expect a genus to contain only a small number of species - it is, after all, the smallest standard grouping of species that there is. And, at least for mammals, this is typically the case. Many genera, in fact, have only one known species, or at least only one that isn't extinct (as is the case for our own genus, Homo, for example). But there are some exceptions, cases where there are so many incredibly similar species that we just have to lump them all together.

The single largest mammal genus, as commonly defined today, is Crocidura, which represents nearly half of every species of shrew we know about. But even the second largest, Myotis, is a whopper.