Malagasy Giant Jumping Rat
Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"
This time I bring you a critter that I don't know well at all! This is the Malagasy Giant Jumping Rat, Hypogeomys antimena. Locally it is known as the Votsota or Votsovotsa. This very rare rodent occurs on Madagascar, in a very small patch of forest on the western side of the island. Many people know of the lemurs of Madagascar, but there are many other fascinating creatures that also live there and only there, and this is one of them. I hope to soon bring you more of the lesser-known Madagascan animals.
Madagascar already started separating from Africa during the heyday of the dinosaurs. Today, at the closest point, over 400 km/250 miles of ocean separates the huge island from the huge continent. This separation is why Madagascar's wildlife is so different from that of Africa: for millions of years, things have been evolving on Madagascar in isolation. Nevertheless, the isolation is not complete. The most devastating invasion of Madagascar's privacy happened a couple of thousand years ago, when we, humans, reached the island and settled there. This caused a massive extinction of native Madagascan species; those that survive today are just a sad remnant of what used to be there.
But there have been other, earlier, and more benign invasions. Indeed, many of the living things on Madagascar today have not been there for all time, since it separated from Africa, but are descendants of more recent arrivals. These include the lemurs and also the unique Malagasy predators like the Fossa. These have arrived periodically from Africa, somehow crossing the substantial seaway. We don't quite know how they did it, but a possibility is that they hitchhiked on big branches or entire trees that may have been uprooted and washed into rivers and swept out to sea during storms or floods.
Many of the rodents of Madagascar are probably also fairly recent arrivals. The Malagasy giant jumping rat, for instance, is a quite modern rodent, not much different from many African rats and mice. This means its ancestors probably arrived in Madagascar relatively recently – we're still talking several million years, though. It has been long enough for these rats to evolve several unique features. Looking at them, they are somewhat rabbit-like. They have comparatively short faces, long ears, and especially long and powerful hind legs. They are reminiscent of small kangaroos, like the Spring Hare of Africa, which is only distantly related to them. Giant jumping rats are indeed quite large, reaching 58 cm/23" in total length, including their stout tails, and 1.2 kg/2.6 lbs in bodyweight.
Another feature of this rodent is that it breeds much less prolifically than what we associate with typical rodents. This is another feature of animals that have small ranges or that are confined to islands. Where there is not much food and living space, creatures start conserving resources by breeding less frequently. This strategy also works well where there are not many predators. Giant jumping rats appear to have been relatively secure in the past. They are monogamous, the mated male and female staying together for life. They also mature fairly slowly, males and females only starting to reproduce at the age of one and a half to two years. Females give birth in the summer, bearing just a single baby at the time, sometimes giving birth twice in one season. They have intensive parental care of their young. The male, especially, guards his children with great enthusiasm. Young males remain with their families for one year, the females remain for two years. The couples and their young offspring live in territories, which they mark off with urine, faeces and scent glands, and defend from other rats.
For the sake of security, these rats are completely nocturnal. By day, they stay in their burrows, which they dig themselves in the forest understory. They block up the entrances of the burrows from the inside by pushing wads of soil outwards. This protects them against their main enemies, the Malagasy ground boas, and the Fossa (these are also not as fully nocturnal as the rats are). Emerging by night, they crisscross the forest in search of seeds, nuts, fallen fruits and fresh leaves. They nibble the bark of trees and will catch and eat invertebrate critters as well. Typically scurrying around on all fours, they use their long hind legs for rapid, long and high leaps to escape from predators.
Today, unfortunately, these rats have to contend with new predators: cats and dogs brought in by humans. Cats and dogs are both somewhat better at catching their prey than the fossas and other native Madagascan predators are. Also the humans and their animals brought in diseases to which the rats are susceptible. One of these is toxoplasmosis, caused by a parasite. This parasite lives in both cats and rodents, and actually changes the behaviour of the rodents, making them fearless of cats, or even makes them seek out cats, to make it easier for the parasite to transfer from one host to the other! This means the rats now have to work harder to survive. But that takes time. They will have to evolve to become even more wary, and to have more babies, giving them a better chance of survival. Until that happens, they will need serious conservation efforts. Today the habitat of these rats is conserved in the Kirindy Forest Reserve, and there are also several captive populations around the world where they are bred so as to augment their numbers. I really hope this unique rat will survive well into the future.