There are two species (Corbet 1978; Filippucci et al. 1988; Harrison 1972; Harrison and Bates 1991; Kock 1985; Nader, Kock, and AI-Khalili 1983):
Although E. melanurus sometimes has been treated as a subspecies or synonym of E. quercinus, it is now generally accepted that the two are highly distinctive species (Corbet and Hill 1991; Filippucci et al. 1988; Harrison 1972; Harrison and Bates 1991; Holden in Wilson and Reeder 1993). Skeletal remains from archeological sites dating to Roman times in Britain probably represent individuals imported for culinary purposes (O'Connor 1986).
Head and body length is 100-175 mm, tail length is 90-135 mm, and weight is 45-120 grams (Grzimek 1975; Van Den Brink 1968). The pelage is short except at the tip of the tail, where it is long and forms a tuft. The general coloration of the upper parts ranges through several gray and brown shades. The underparts are creamy or white. There are usually some black markings on the face. In E. quercinus the tail is distinctly tricolored dorsally, having a cinnamon brown proximal half, a broad black preterminal band, and a white tip (Ognev 1963). In E. melanurus the proximal third of the tail is brownish white and the remainder of the tail is usually black (Harrison 1972). Females have eight mammae.
The common name is not fully appropriate as Eliomys is generally found in extensive forests in Europe (Grzimek 1975; Ognev 1963). It also occurs in a variety of other habitats, including swamps, rocky areas, and cultivated fields. In the Middle East it has been found from the steppe desert of Hejaz to the high mountains of Lebanon (Harrison 1972). It shelters in such diverse places as hollow trees, branches of shrubs, crevices among rocks, and foresters' huts. A bird or squirrel nest may be used as a foundation for a shelter, but when Eliomys builds a complete nest it is made of leaves and grass, is compact and globular in shape, and usually is located 0.8-3.0 meters above the ground. In some areas Eliomys is highly arboreal and is reported to be extremely graceful and agile (Ognev 1963), but in other places it occurs where there are no trees at all (Harrison 1972). It is apparently most active by night. In some areas it is known to gain weight in the autumn and to become dormant during the coldest part of winter The diet consists of acorns, nuts, fruits, insects, small rodents, and young birds. Ognev (1963) suggested that Eliomys is primarily a predator.
According to Grzimek (1975), large numbers of individuals may live in close proximity and share sleeping and feeding sites. Except during the mating season there is no fighting, not even when two unrelated groups come together. Eliomys is very noisy and has a variety of calls (Ognev 1963). Females are thought to be polyestrous. The estrous cycle is 10 days, and breeding extends from February to October in Europe (Hayssen, Van Tienhoven, and Van Tienhoven 1993). In southwestern Spain there are birth peaks in March-May and August-October (Moreno 1988). Births evidently occur at about the same time in Morocco (Moreno and Delibes 1982). The gestation period is about 22-28 days, and litter size is two to eight young. The young open their eyes after about 21 days and are weaned at 4 weeks. A captive specimen lived 5 years and 6 months (Jones 1982).
Pucek (1989) indicated that Eliomys has become rare in much of its range because of destruction of its forest habitat and is endangered in the Czech Republic, Slovakia, Poland, and Finland. Amori, Cantini, and Rota (1995) stated that the subspecies E. quercinus sardus, of Sicily, E. q. dichrurus, of Sicily, and E. q. liparensis, of Lipari Island, have become very rare. The IUCN now classifies the entire species E. quercinus as vulnerable and E. melanurus as near threatened.
Information taken from: Nowak, R.M. (Ed.). Walker's Mammals of the World. 6th Edition. The John Hopkins University Press. Baltimore and London, 1999.