694.

Olive Soft-haired Mouse

Abrothrix olivacea

French: Abrothrix olivatre / German: Olivbraune Andenfeldmaus / Spanish: Ratdn de pelaje suave olivaceo

Other common names: Olive-colored Akodont, Olive Grass Mouse

Taxonomy. Mus olivaceus Waterhouse, 1837, “ Valparaiso,” Valparaiso, Chile.

Abrothrix olivacea is in the subgenus An-gelomys. There is not agreement among different evidence supporting trinomial classification of A. olivacea. Cytochrome-b sequence analysis apparently favored cohesive clades such as canescens or tarapacensis. A comprehensive study including both Argentinean and Chilean populations is needed. Monotypic.

Distribution. Chile (excluding extreme S island territory) and WC to S continental Argentina .

Descriptive notes. Head-body 80 mm,tail 53 mm, ear 14 mm, hindfoot 20 mm, and weight 13 g (Neuquén Province); head-body 83 mm, tail 57 mm, ear 14 mm, hindfoot 20-5 mm, and weight 13 g (Chubut Province); head—body 89 mm, tail 58 mm, ear 14 mm, hindfoot 21 mm, and weight 17 g (Santa Cruz Province); mean values for adult males and females. Adult males weighed a significant 9-2% more than adult females. See general characters of the genus under the Long-haired Soft-haired Mouse (A. longipilis) account. The Olive Softhaired Mouse is a small species of Abrothrix, rivaling in body size the Andean Soft-haired Mouse (A. andina). Pelage color and body measurements vary geographically, ranging from olive-brown to gray or pale ocherous. The Olive Soft-haired Mouse differs from the Yellow-nosed Soft-haired Mouse (A. xanthorhina) in that its countershading is not sharp.

Habitat. High Andean deserts to almost all habitats in southern South America ranging from semiarid scrub habitat and bushy steppes; bunchgrass habitats; moister habitats such as meadows, thick grasses, Nothofagus (Nothofagaceae) forests, dense coastal forest of N. betuloides, Drimys winter ( Winteraceae) and Lomatiaferruginea ( Proteaceae), and grassy meadows with sparse shrub cover; basaltic tablelands; and rocky expositions

Food and Feeding. The Olive Soft-haired Mouse eats berries, seeds, arthropods, green vegetation, and fungi.

Breeding. The Olive Soft-haired Mouse breeds from spring to summer (October— March). Litters average c.5 young. Females produced 2-3 litters/season, and older females tended to have large litters.

Activity patterns. The species is nocturnal, diurnal, terrestrial, and good climber.

Movements, Home range and Social organization. The Olive Soft-haired Mouse builds simple nests of grass, underground or sheltered in roots or rocks. It creates runways in dense grass and also lives in burrows constructed by other rodents. Home ranges vary geographically and seasonally. In central Chile, home ranges were 1779 m? in winter and 2776 m® in spring; in north-western Argentine Patagonia, home ranges were 548 m* for females and 598 m?® for males during non-breeding season and increased to 610 m* for reproductively active females and 1307 m? for males. Extensive overlap between home ranges of males and females was observed. Populations are subject to important fluctuations related to El Nino—Southern Oscillation (ENSO) and bamboo dynamics. Densities in Chilean shrubland-grassland were 37-7 ind/ha (maximum in autumn) and 30-3 ind/ ha in August and 97 ind/ha in November; in temperate Chilean woodlands, density peaked in winter at 37-9 ind/ha; in Nothofagus forest Argentinean north-western Patagonia, densities were 0-1-9 ind/ha in spring and increased to 4:2-17-9 ind/ha in autumn; and in north-western Patagonian steppes, density reached a maximum of 40 ind/ha in March—the month with a record abundance for this rodent. The Olive Soft-haired Mouse is one of the most abundant and ubiquitous sigmodontines in Patagonia.

Status and Conservation. Classified as Least Concern on The IUCN Red List (as A. olivaceus, and including A. xanthorhina).

Bibliography. Abud (2011), Allen (1905), Apfelbaum & Reig (1989), De Santis & Justo (1980), Gonzalez, Murua & Feitl (1982), Gonzalez, Murda & Jofre (2000), Kelt (1994, 1996), Kelt et al. (1994), Lessa et al. (2010), Lozada etal. (1996), Massoia (1981), Meserve, Kelt & Martinez (1991), Meserve, Lang, Murua et al. (1991), Meserve, Lang & Patterson (1988), Monjeau, Birney et al. (1998), Monjeau, Bonino & Saba (1994), Monjeau, Sikes et al. (1997), Murta & Gonzalez (1985), Murla, Gonzalez & Briones (2005), Murua, Meserve et al. (1987), Pardinas, Teta, Cirignoli & Podesta (2003), Pardinas, Teta, D'Elia & Lessa (2011), Pardinas, Teta & Udrizar (2008), Patterson, Gallardo & Freas (1984), Patterson, Pardinas & D'Elia (2008), Patterson, Smith &Teta (2015), Pearson (2002), Pearson & Smith (1999), Polop et al. (2015), Rodriguez-Ser rano, Cancino & Palma (2006), Rodriguez-Serrano, Hernandez & Palma (2008), Rodriguez-Serrano, Palma & Hernandez (2008), Sage etal. (2007), Smith et al. (2001), Spotorno et al. (1990), Teta et al. (2017), Udrizar (2009), Yanez et al. (1979).