367.

Hairy-soled Conyrat

Reithrodon auritus

French: Reithrodon de Patagonie / German: Haarsohlige Kaninchenratte / Spanish: Rata conejo sin pelos

Other common names: Bunny Rat

Taxonomy. Mus auritus G. Fischer, 1814, type locality not given. Restricted by U. F.J. Pardinas and colleagues in 2015 to “probably near Pila, south side of the Salado River,” Buenos Aires Province, Argentina.

Three subspecies are recognized.

Subspecies and Distribution.

R.a.auritusG.Fischer,1814—CEArgentina.

R.a.cuniculoidesWaterhouse,1837—SArgentinaandadjacentChile.

R. a. flammarum Thomas, 1912 — Tierra del Fuego (extreme S Argentina and Chile); there is an unconfirmed record from the FalklandsIs.

Descriptive notes. Head-body 126-141 mm, tail 79-95 mm, ear 23-25 mm, hindfoot 32-34 mm; weight 52-116 g (mean 80 g). Males and females are the same size. See general characters of the genus under the North-western Conyrat ( R. caurinus) account. The Hairy-soled Conyrat is large and soft-furred, with enormous eyes, moderately short tail, long rather furry ears, and tuft of pale fur at bases of ears. Soles of hindfeet are furry, and first and fifth toes are very short, not reaching beyond bases of middle three toes. Soles are more densely haired than in the Naked-soled Conyrat ( R. typicus); tail is bicolored. Chromosomal complement is 2n = 34, FN = 32.

Habitat. Open habitats from prairies and natural grasslands or deeply transformed agroecosystems in central Argentina, to steppes and shrublands in northern Patagonia, tablelands and extensive rocky areas in central Patagonia, and grassy steppes and tundra in southernmost South America from sea level to elevations of ¢.2200 m. The Hairy-soled Conyrat is most common in treeless open habitats, such as steppes and prairies, usually near green grass.

Food and Feeding. The Hairy-soled Conyrat is herbivorous. In south-eastern Buenos Aires province, stomach contents consisted only of grasses, especially Poa spp. and Lolium multiflorum (both Poaceae). Composition of fecal pellets collected from live-trap captures in steppe-forest ecotone of Argentinean Patagonia positioned the Hairy-soled Conyrat as herbivorous-graminivorous, with diets of nearly 50% Poa spp. In captivity, Hairy-soled Conyrats ate fresh green vegetation equalto their weight nightly. Feces are fibrous, thick, short, and greenish (when fresh), and pointed at one end. Latrines are not recorded, but feces are very numerous along runways or near tunnel openings.

Breeding. Hairy-soled Conyrats with reproductive signals are recorded from spring to summer. Litters had 1-8 in utero fetuses (mean 4-5). Juveniles (more than 50 g) were recorded in spring but in higher numbers and proportions in summer and autumn. Spring populations have a few old overwintering individuals, some middle-aged overwintering individuals, and numerous young individuals that mature in summer. In autumn, the oldest individuals disappear and are replaced by middle-aged individuals. The Hairy-soled Conyrat reaches its population maxima at the end of austral autumn. Nests are made of plant materials, or sheep’s wool in Tierra del Fuego.

Activity patterns. The Hairy-soled Conyratis terrestrial. Activity began in evening and lasted until early hours of morning. Feeding occupied most of the active period, with short foraging periods interspersed.

Movements, Home range and Social organization. The Hairy-soled Conyrat lives in extensive tunnel systems in green grassy turf. During winters, individuals remain active in burrows under snow. Individuas excavate tunnel systems 4-7 cm in diameter, usually vertically through turf, with grouped entrance openings but without evidence of earth plugs. Individuals were also trapped in tunnels dug by the caviomorph Cienomys (tuco-tucos), and they tolerate cohabitation with other sigmodontines. From very low minimum abundance, the Hairy-soled Conyrat can reach peaks of ¢.10-15 ind/ha (minimum known alive). Longest recapture times were eight months, but the study of cohorts suggests maximum longevity of 15 months. Field observations suggested some degree of sociability; at least many individuals use the same runways or burrows in the same night. Recorded lineal dispersal were typically less than 50 m.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Allen (1903b), Busch (1986), Guthmann et al. (1997), Hershkovitz (1955), Kelt (1994), Mann (1978), Monjeau (1989), Monjeau et al. (1998), Ortells et al. (1988), Osgood (1943a), Pardinas & Galliari (2001), Pardinas, Galliari & Teta (2015), Pardinas, Jayat & D’Elia (2016), Pearson (1987 1988, 1995), Pearson & Patton (1976), Philippi (1900), Pine et al. (1979), Polop, FE et al. (2015), Polop, J.J. (1989), Reig (1964, 1978), Reise & Venegas (1987), Ringuelet (1955), Scaglia et al. (1982), Steppan (1995), Tate (1932a), Thomas (1912¢c, 1916c, 1920b, 1927¢), Vorontsov (1959), Waterhouse (1837, 1839).