Married Until Death

Hypogeomys antimena, Madagascar’s largest living rodent, reaches roughly 1.2 kilograms and the size of a rabbit, with long pink ears, a pink snout, and a habit of sitting bolt upright that only deepens the resemblance. Alarmed, it abandons its usual walk entirely and bounds away on its hind legs like a small kangaroo, the detail that earned it the name giant jumping rat.

The largest rodent on the island, and the first one anyone ever described.

It was described in 1869 by the naturalist Alfred Grandidier, the first native rodent ever formally recorded on Madagascar. Its closest relatives, the short-tailed rats of genus Brachyuromys and the forest rats of genus Nesomys, place it within Nesomyinae, a rodent subfamily found nowhere else on Earth.

Among rodents, lifelong monogamy is close to unheard of. Hypogeomys antimena practices it anyway: pairs form and generally stay bonded until one partner dies, sharing and maintaining an extensive network of burrows dug into the sandy, leaf-littered soil of Kirindy’s dry deciduous forest.

That stability offers little defense against the forest’s two main predators. Fossas take a steady toll on adult breeding pairs, and ground-dwelling boas add further pressure from below, hunting through the same burrow systems the rats depend on for shelter. A monogamous life does not, in this forest, translate into a safe one.

Hypogeomys antimena is the smaller survivor of its own genus. Hypogeomys australis, an extinct relative weighing at least two kilograms, roughly twice the living species, is known from subfossil jaw material found in Andrahomana cave and dated to about 4,400 years ago, alongside remains from the central highlands near Antsirabe. It once ranged across much of the southern half of Madagascar.

Even the living species was never confined to its current pocket of forest. Subfossils recovered at Ampoza and dated to roughly 1,350 years before present show Hypogeomys antimena occupying territory far to the southwest of where it survives today, evidence of a range that contracted long before conservation status reports began tracking it.

The giant jumping rat now survives in a territory of roughly 100 to 200 square kilometres of dry deciduous forest north of Morondava, centred on Kirindy. It is one of just six native Malagasy rodent species considered endangered, and researchers studying it have noted that its actual situation is more urgent than its official conservation category alone suggests, given how sharply deforestation and habitat fragmentation have already cut into its small breeding population.

Specimens have been captured over the years for Tsimbazaza Zoological Park in Antananarivo, a small insurance policy of sorts for an animal whose entire wild population now fits inside a stretch of forest most cities would consider modest.