160.

Pyrenean Pine Vole

Microtus gerbii

French: Campagnol de Gerbe / German: Pyrenaen-Kleinwihimaus / Spanish: Topillo de los Pirineos

Other common names: Gerbe's Vole

Taxonomy. Arvicola (Microtus) gerbii Gerbe, 1879, Dreneuf, lower Loire, France.

Widely used species name gerbe: is an unjustified emendation of the original gerbii. Microtus gerbii is in subgenus 7Terricola and duodecimcostatus species group. Earlier it was known as M. pyrenaicus, which is a nomen dubium (dubious name) meaning that taxonomic identity of a nominal species-group taxon cannot be determined with certainty. It was classified in genus Pitymys . Four subspecies are occasionally recognized but are ill-defined. Monotypic.

Distribution. France (roughly W of Massif Central and S of Loire River), Andorra, and N & NE Spain (from E Cantabria to E Pyrenees).

Descriptive notes. Head—body 92-108 mm,tail 22-36-6 mm; weight 17-32 g. The Pyrenean Pine Vole is moderately sized, with short tail. Females have two pairs of inguinal nipples. Pelage on back is buffy brown to dark brown and gray on belly. Skull is more robust than in other species in group duodecimcostatus . Supraorbital ridges are relatively prominent but remain separated in interorbital region. Alveolar process is hardly notable on outer side of mandibular ramus. Upper incisors are only slightly proodont. Molars do not differ markedly from those in the Lusitanian Pine Vole ( M. lusitanicus).

Habitat. Forest edge, clearings, and meadows with deep soil and dense vegetation at elevations of 800-2035 m. The Pyrenean Pine Vole occurs in areas with an annual isotherm of 15-16°C and precipitation above 1000 mm/year. It has been recorded in dense vegetation along montane brooks and in stone walls encircling fields. It avoids steep slopes and skeletal soil (35% rocky).

Food and Feeding. The Pyrenean Pine Vole mainly eats leaves and stems of dicotyledonous plants. Bulbs of fume wort ( Corydalis solida, Papaveraceae), autumn crocus ( Colchicum montanum, Colchicaceae), and pignut ( Conopodium majus, Apiaceae) were found in caches. Mean weight of cached parts of geophytes was 1 g.

Breeding. Breeding of the Pyrenean Pine Vole occurs throughout the year but is most intensive in April-November. Females were recorded with 1-4 embryos (most often 2-3).

Activity patterns. Pyrenean Pine Vole is less fossorial than the Mediterranean Pine Vole ( M. duodecimcostatus) or the Lusitanian Pine Vole. It is also less proficient at swimming, but it does climb.

Movements, Home range and Social organization. Pyrenean Pine Voles occur in social groups of 5-16 individuals. Level of aggressiveness is low in interactions involving individuals from the same and different social groups.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as M. gerbei) Overall distribution is slightly over 200,000 km?.

Bibliography. Borghi & Giannoni (1997), Borghi et al. (1994), Giannoni, Borghi & Laconi (1999, 2001), Gosélbez & Luque-Larena (2002), Krapp (1982d), Louarn & Quéré (2003).