Jerboas are small rodents with long forelimbs, short hindlimbs, and long tails. Even though they resemble miniature kangaroos of the family Macropodidae and hop around like them, they are grouped under a separate family, Dipodidae, based on phylogenetic data. When in danger, they hop more energetically, covering distances of about 10 ft.
It is believed that these rodents originated around 16.4 to 11.2 million years ago in the Middle Miocene Epoch. They are found in the deserts and steppes of North Africa, Asia, and Eastern Europe, where they usually live in burrows. Though primarily herbivorous, some species, like long-eared jerboas, also feed on insects.
Their body length ranges between 1.6 to 10 inches (4 to 26 cm), not including the tail, which is usually longer than the body and measures between 2.75 and 12 inches.
These rodents are characterized by a mouse-like body, long hindlimbs (around four times longer than the forelimbs), mostly a tufted, long tail, and large feet. Some species, such as the four-toed jerboa, have long, rabbit-like ears, whereas others have short, rounded ears resembling those of a rat. A dense layer of fur, light-colored and silky (sometimes velvety), covers their body.
Their limb morphology is also unique in that all metatarsal bones fuse into a distinctively long cannon bone. This bone provides these animals the base to reach greater heights while jumping. The hindlimbs possess three to five toes.
A large, oval-shaped hole is found at the base of the skull (the occipital bone) called the foramen magnum. This hole is forward-shifted, which enables them to use their two hindlimbs for locomotion (bipedalism).
Jerboas were once believed to be paraphyletic, along with birch mice and jumping mice, and all three were classified under the family Dipodidae. However, phylogenetic studies later revealed that these groups have different evolutionary origins. As a result, birch mice and jumping mice were reclassified into their own families, Sminthidae and Zapodidae, respectively. Although jerboas resemble kangaroo rats (genus Dipodomys), they are phylogenetically unrelated.
Currently, 33 species of jerboas are classified under 5 subfamilies and 13 genera.
Jerboas are found both in hot and cold deserts as well as in the steppes of North Africa, Asia, and Eastern Europe. They mostly live in underground burrows built close to vegetation cover.
Jerboas primarily feed on plant matter but often struggle to bite through harder parts, such as seeds. However, certain species, like long-eared jerboas, mainly eat insects, such as beetles. In some cases, they are found to feed on smaller, weaker jerboas opportunistically.
These rodents are usually crepuscular, with their peak activity occurring at twilight. Due to the intense daytime heat in deserts, they stay in their burrows during the day and only come out as the temperature begins to drop in the evening.
These rodents typically hop, skip, jump, and run around using both their hindlimbs (bipedal locomotion), resembling miniature kangaroos. They move in a zig-zag pattern, quickly changing speed and direction to baffle their enemies.
While hopping, they usually cover a distance of about 10 to 13 cm with each stride. When threatened, these hops become more dynamic, reaching speeds of up to 25 km/h, with each leap covering as much as 3 m (10 ft).
Since jerboas are mostly the residents of deserts, they need to avoid the scorching heat (in hot deserts) or the chilling cold (in cold deserts) to live freely. To do so, they dig burrows in the ground and take shelter in them.
They typically build four types of burrows: a temporary summer-day burrow, a temporary night burrow, and two permanent burrows (one for summer and the other for winter). The temporary burrows are generally shorter than permanent burrows. During summer, they use the permanent burrows to raise their young, while in winter, they use them for hibernation. In general, winter burrows are deeper and have more holes for entry than summer burrows.
Sometimes, they plug the entrance holes of these burrows to prevent them from outside heat or cold. In the rainy season, they build tunnels in hills or mounds to prevent being washed off by floods.
They rarely drink water since they obtain most of their hydration from the moisture of their food.
Although they prefer moist leaves, during the hot summer months, the leaves dry out. In such circumstances, jerboas dig up the roots of desert plants since they have the highest water content in plants.
Though these rodents typically live around 2 to 3 years, they can survive up to 6 years in the wild.
Jerboas typically mate during spring or summer (between March and July) when food resources are plentiful. Around this time, they also produce high amounts of gonadotropin-releasing hormone (GnRH), a hormone that directly influences the sexual activity of these rodents.
The females breed twice a year, producing two to six (mostly three) young after a gestation period of 25 to 35 days. These young are born naked and develop hind limbs when they are about 8 weeks old. The mother nurses the young till they are ready to be weaned off.
At around 11 weeks, they are capable of jumping, and at around 14 weeks, they attain sexual maturity.
Foxes, owls, and snakes mostly attack them. In Central Asia, some jerboas are also preyed upon by the little owl (Athene noctua).
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