|
|
- ITSES - |
Eurasian Insectivores and Tree Shrews:
Status Survey and Conservation Action Plan
Published 1995
Continued from previous page | Go to next page
2.3.3 Family Talpidae: Moles and Desmans
This family of 17 genera and 42 species occurs widely throughout the Old and New World. In Eurasia, 12 genera (35 species) are represented (Table 2.5) with representatives distributed northwards to about 63'N, south to the Mediterranean and east to Japan. Remaining members of the family are widespread in the New World, ranging from southern Canada to northern Mexico.
|
|
|
| Genus | Species |
|
|
D. moschata |
Sub-family Desmaninae
GENUS DESMANA -
Return to Top of Page | Table
of contents
The genus Desmana consists of a single, highly specialised species
found only in eastern Europe.
Russian desman (Desmana moschata) - Return to Top of Page | Table of contents
Taxonomy: Desmana moschata Linnaeus 1758.
IUCN Category of Threat: Vulnerable (Bl and 2c). This species is included in the Red Data book for Russia, Ukraine, Belarus and Kazakhstan.
Description: An aquatic insectivore of still and slow moving water. Body length ranges from 180-215mm, tail length from 170-215mm. Easily distinguished by the elongated proboscis which is grooved above and below; it is highly flexible and used for exploration. The tail is laterally compressed and is largest at the base where there are special scent glands that give the animal a distinctive, musky odour. Rings of scales encircle the tail, with a few hairs growing between them. The hind feet are webbed to the tips of the toes and along the edges of the feet there are fringes of stiff hairs that further increase the surface area for swimming. The forefeet are only partially webbed and also have hair-fringed edges. The pelage consists of soft, dense underfur which is interspersed with longer, coarser guard hairs. The colour above is a rich reddish-brown, shading to ash-grey beneath.
Distribution: The single species in this genus is found in Russia, Belarus, the Ukraine and Kazakhstan. Desman populations are reported from the basins of the following rivers: Volga (23,000 animals), Don (about 12,000 animals), Dneiper (2000-3000), Ural (2000), and the Uj and Tobal rivers (2500 animals). This species has been the subject of previous re-introduction efforts (see below and Appendix 1). There are now five nature reserves and 80 refuges for desmans (Khakhin, 1993).
Habitat: Slow-flowing rivers, lakes, ponds, canals and marshland. Permanent supply of freshwater essential. Occasionally found in brackish waters. Burrows are created in banks, usually under vegetation, and are used for shelter and breeding.
Ecology and behaviour: A semi-aquatic species which feeds on insects, crustaceans, molluscs, fish, amphibians from freshwater streams and lakes. A total of 90 food items have been recorded in its diet (Onufrienja and Onufrienja, 1993). A simple burrow system is constructed with the single opening beneath the water level, leading up and away from the water to a large, single chamber. The social organization of this species is unclear, but it appears to be a social species; as many as eight animals have been discovered in a single den. Onufrienja and Onufrienja (1993) reportingon 54 yearsof researchfrom the Oka State Reserve, mention that two animals are usually found at a nest site, occasionally three or four. Largely nocturnal, but also seen during daylight. It appears to be somewhat nomadic. Such records may originate from its tendencies to migrate when rising flood waters threaten the nest. When flood waters are high, desmans may nest in trees and bushes. In addition, however, desmans may move from seasonally shallow lakes where they breed, to deeper lakes to over-winter. Onufrienja and Onufrienja (1993) report a close correlation between rainfall and overall desman numbers: when water levels are high, desmans are offered good overwintering conditions. When water levels are low, desmans may need to migrate overland to other overwintering sites. Breeding may take place throughout the year, but most appears to be concentrated in spring and autumn (Onufrienja and Onufrienja, 1993). Litters of 3-5 young have been recorded (Ognev, 1962). The average litter size recorded from Oka Reserve was 3.6 (Onufrienj a and Onufrienja, 1993).
Setting a live trap for the Russian desman (Desmana moschata).
(Photo by Gennady Khakhin)
In contrast to the fast-flowing habitat of the Pyrenean desman (Galemys pyrenaicus) the Russian desman (Desmana moschata) prefers shallow lakes and standing water bodies. (Photo by Gennady Khakhin)
More at home in the water, the Russian desman (Desmana
moschata) occasionally comes on to land to forage and disperse. (Photo
by Gennady Khakhin)
Air tracks beneath the spring ice lead to the nest of a Russian
desman (Desmana moschata). (Photo by Gennady Khakhin)
Presence of the Russian desman (Desmana moschata)
may be detected by the air tracks they leave beneath the ice cover. (Photo
by Gennady Khakhin)
Marking experiments have shown that desmans are sedentary animals as
long as environmental conditions remain stable. As a rule, desmans use
the same burrows for several years. Radiotracking experiments have shown
that adult females have territories ranging from 0.34-0.56ha, with 2-6
nest holes. The Russian desman was relatively abundant until the late 19th
century when hunting pressure for its valuable fur eliminated and decimated
many populations. From 1817 to 1819, for example, Russia exported 325,500
skins to China; some 100,000 skins were sold on the home market at the
Nizhni Novgorod fair in 1836 (Kaplin, 1960). By the turn of the 20th century,
however, about 20,000 skins were being processed annually (Grzimek, 1975).
Desman hunting was banned in 1929 and attempts were made to breed this
species in captivity. As a result of this initiative, a total of 10,000
animals were released in 30 republics and regions of the former USSR (Khakhin,
1993). Some new populations were established. Lack of management and poor
protection, together with some licensed hunting of desmans in 1940, meant
that the overall number of animals did not increase. Hunting was again
banned in 1957. The number of free-living desmans has continued to decline;
estimates suggest that the overall population is now about 40,000-50,000
animals. Apart from hunting, the main reasons for the decline of this species,
both in terms of overall number and distribution, have been water pollution,
creation of impoundments, drainage, clearance of riparian vegetation, entanglement
in fishing nets and competition for breeding sites with introduced nutria
and muskrats. This specieshasbeenthe subjectof much investigation; one
ongoing study at Oka State Reserve, is now entering its 55th year (see
Onufrienja and Onufrienja, 1993).
A Russian desman (Desmana moschata) caught in a special live trap. (Photo by Gennady Khakhin)
GENUS GALEMYS - Return to Top of Page | Table of contents
The genus Galemys consists of a single species, a semiaquatic
insectivore which is restricted to the Pyrenees Mountains, northern and
Central Spain and northern Portugal.
Pyrenean desman (Galemys pyrenaicus) - Return to Top of Page | Table of contents
Taxonomy: Galemys pyrenaica E. Geoffroy 1811. One subspecies G.p. rufulus has been proposed from Iberia, but supporting evidence of this claim is weak and probably a result of colour variability.
IUCN Category of Threat: Vulnerable (Bl and 2c).
Description: A distinctive species with a body length of approximately 125 mm and an elongated cylindrical tail about 140 mm long. The short fur is thick, dark brown with a metallic gloss on the back. The pelage appears shiny when the animal is underwater. Ventral coloration is light and silvery. The tail is fringed at the end and slightly flattened vertically. This acts as a rudder when swimming, helping to steer and direct the animal as it swims. The long muzzle is black and almost devoid of fur. The snout is widened at the tip where two partially divided lobes are evident, each with an elongated nostril opening on the upper side. The eyes are small and surrounded by short hair. There is no pinna and the auditory meatus is hidden by the fur. The forelimbs are smaller than the hindlimbs. Its feet are webbed and bear large claws (Palmeirim and Hoffmann, 1983).
Distribution: This species is confined to south-western Europe, notably the French and Spanish Pyrenees, northern Spain and northern Portugal. In France, it occurs along the Aude, Agly, Salat, Aspe, Ossau, Ariège, Audour, Tet and Tech rivers (Richard and Vallette-Viallaird, 1969). A more recent revision of the distribution of this species in France can be found in Bertrand (1993). Its precise distribution is less well known in Spain and Portugal, but is known from along streams in the northern part of the central plain in the surroundings of the Picos de Europe and along the Deva River (Corbet, 1966, Niethammer, 1964). Vericaud (1970) gives the following locations for the Spanish Pyrenees: Sierra de Guarra north of Huesca and in the vicinity of Infiesta (Oviedo) and Burguete (Navarro). Due to its tendency to conceal itself, no estimates of the number of animals can be made within a given area. Detection of faeces deposited on rocks or other objects is not a valid means of assessment since fluctuating water levels quickly remove any signs of evidence.
Habitat: Unlike the Russian desman, the Pyrenean species lives along fast-flowing mountain streams. It is occasionally found in slower-moving water bodies, including canals, lakes and marshes at altitudes of 60-1200 m.
Ecology and behaviour: A highly specialised animal adapted to
an aquatic environment. The desman forages mainly at night, feeding on
a wide range of crustaceans and insect larvae, including mayfly, stonefly
and caddisfiy larvae.
A semi-aquatic insectivore of fast-flowing streams, the Pyrenean
desman (Galemys pyrenaicus) spends considerable time grooming itself
on rocks on the river bank. (Photo by David Stone)
The tactile and highly sensory snout of the Pyrenean desman
(Galemys pyrenaicus) assists with the location of prey. (Photo by
David Stone)
Its life history and habitat have been studied and there is some information concerning its distribution. Parts of its range are situated within the Pare National des Pyr6ndes Occidentales and the Parque Nacional de Covadona. It is possible that the species also occurs in the Parque Nacional de Aiguas y Lago de San Mauricio and the Parque Nacional de Ordesa.
This species has declined in recent years because it is bound to a very
vulnerable habitat in a restricted area. It is most threatened by water
pollution and the construction of hydro-electric plants which fragment
the habitat. It has also suffered from direct human persecution either
through over-zealous collecting or from fishermen who (mistakenly) perceive
it as a threat to fish stocks, especially trout. The full impact of these
activities is not known. In Iberia, fears have been expressed on the potential
damage to aquatic species following escape of North American mink (Mustela
vison) from fur farms in northern Iberia. The ecology of this species has
been described in detail by Richard and Vallette-Viallaird (1969) and Stone
(1985, 1986, 1987a,b). More recently, the Pyrenean and Russian desmans
have been the subject of an international conference, the proceedings of
which may be found in Queiroz (1993). (See also Appendix
ll.)