A very different way of life is exhibited by the desmans, of which there are two species. The Pyrencan desman Galemys pyrenaicus is confined to permanent, fast-flowing streams of the Pyrenees mountain range and parts of northern Iberia, the Russian desman Desmana moschata is found only in the slower moving waters and lakes of the western and central Soviet Union Just as moles are superbly adapted for a fossorial way of life, so too are the desmans for water.
The streamlined body of the Pyrenean desman enables it to glide rapidly through the water, propelled by powerful webbed hindlimbs and steered, to some extent, by a long. broad tail.
For any animal living in the snow-fed mountain streams, feeding and retaining body heat are top priorities. Unlike hedgehogs or tenrecs, desmans do not undergo periods of hibernation or torpor and must, therefore, live in optimum habitats to ensure their survival during the winter months when prey is most scarce.
What Do Desmans Eat?
Desmans feed on the larvae of aquatic insects such as the stone fly and caddis fly, as well as on small crustaceans, which they locate by probing their proboscis-like snouts beneath small rocks and by clearing away debris from the stream bed with their sharp elongated claws. Prey is consumed at the surface where following each dive, a a rigorous body grooming is carried out. This is an essential activity as it ensures that the fur is not only kept clean and in good condition but also maintains its water-repellent properties by oil all over the body from sebaceous glands spreading.
How Do they Build Nests?
Desmans construct their nests in the banks of streams, The Russian desman actually excavates a complex burrow, which it may share with other desmans, while the smaller Pyrenean species occupies a strictly solitary nest, usually created by enlarging an already existing tunnel or crevice. Nests are composed of leaves and dried grasses and are always located above the water level.
Little is known about the breeding behavior of desmans. In the Pyrenean desman, mating takes place in spring (March to April), and, as these animals usually form a stable pair bond, competition for mates by solitary males is often quite severe. At this time of year, an interesting phenomenon occurs for each pair of animals: males become far more protective, spending most of their active time at the upper and lower reaches of their riverine territory. Energy is thus spent on protecting the feeding resources of that territory and, more importantly, the female. Females, in contrast, spend most of their active time feeding, surveying for a suitable nest site, and gathering nesting materials
Young are born after a gestation period of about four weeks and are cared for solely by the female. Juveniles first leave the nest at about seven weeks, at which stage they are already proficient swimmers. Juveniles remain within the parents territory until they are about two and a half months old, at which stage they leave in order to secure a mate and breeding territory for the coming year.
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