586.

Azara’s Grass Mouse

Akodon azarae

French: Akodon de dAzara / German: Azara-Graslandmaus / Spanish: Raton campestre de Azara

Other common names: Azara's Akodont

Taxonomy. Mus? azarae]. B. Fischer, 1829, “Paraguaya.” Clarified by U. F. J. Pardinas and colleagues in 2007 as “Sao Gabriel (30°19°S, 54°19°W, 118 m) ... in the Brazil ian State of Rio Grande do Sul.”

Akodon azarae is one of the more studied species of Akodon in ecological, physiological, and behavioral terms, but its taxonomy is poorly studied. Unspublished molecular results suggest a well-marked geographical structure within the current concept of the species, with different clades encompassing Brazilian—-Uruaguayan, north-eastern Argentinean and Paraguayan, and central Argentinean populations. If a trinomialclassification needs to be applied, available names are A. a. azarae (including Mus arenicola), A. a. bibianae, and A. arenicola hunteri. Monotypic.

Distribution. E & S Paraguay, S Brazil, NE & EC Argentina, and Uruguay.

Descriptive notes. Head-body 93 and 96 mm, tail 68 and 84 mm, ear 14 and 17 mm, hindfoot 21 and 25 mm; weight 20 and 29 g (mean values for pooled males and females from Formosa and Buenos Aires provinces, Argentina). Azara’s Grass Mouse is a medium-sized species of Akodon . Dorsum is olive brown to deep brown, usually tinged buffy on sides and cheeks; ventral hairs are gray-based and buffy tipped, and thus venter is moderately demarcated from dorsum; ears are covered in short brown hairs; hindfeet are tan above; and tail is bicolored.

Habitat. Natural or modified grasslands and prairies, including gallery forests, shrublands in hilly environments, sparse woodlands, and various temperate lowland habitats. In central Argentina, Azara’s Grass Mouse is found in a great variety of habitats with high grass cover, including natural pastures, road borders, borders between cultivated fields or pastures, and railway banks.

Food and Feeding. Azara’s Grass Mouse mainly eats coleopterans and grass.

Breeding. Breeding of Azara’s Grass Mouse occurs mainly in spring and summer (mid-September to mid-March). Average gestation is 22-7 days, and sexual maturity is reached at 60 days old. Young are weaned at 14-15 days old and exclusively cared for by females. A female has an average of three litters of 4-6 young in her lifetime.

Activity patterns. Azara’s Grass Mice are continuously active but mainly during the day and crepuscular hours. They are terrestrial, with a slight tendency to dig.

Movements, Home range and Social organization. In Buenos Aires Province, populations of Azara’s Grass Mice turnover annually, and individuallife span is c.12 months. Typical density at the beginning and middle of the reproductive period is ¢.60 ind/ ha, and sex ratio is typically male-biased (1-8 male:1 female). There is marked annual variation in abundance; low numbers occur in spring (September—December), abundance peaks in autumn (May), and it decreases dramatically in late winter to early spring (August-September). Average home range was 254-9 m*® for females, 296-9 m” for resident males, and 196-7 m?® for non-resident males. Polygynous mating system operates with female defense. Males can adjust their spacing strategy (home range sizes) to increase mating opportunities at low densities of females; male mating tactics can determined by number of receptive females to which they have access.

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

Bibliography. Antinuchi & Busch (1999, 2000), Avila (2013), Barlow (1969), Bianchi & Contreras (1967), Bianchi & Merani (1984), Bilenca & Kravetz (1998, 1999), Bilenca et al. (1994), Bonatto (2013), Bonatto, Coda et al. (2013), Bonatto, Gémez et al. (2012), Bonatto, Steinmann et al. (2015), Bonaventura & Kravetz (1984, 1989), Bonaventura et al. (1992), Busch & Kravetz (1992), Busch, Alvarez et al. (1997), Busch, Mino et al. (2001), Contreras (1979), Dalby (1975), D'Elia & Pardinas (2016c), Del Valle & Busch (2003), Ellis et al. (1997), Gomez et al. (2011), Gonzalez (2001), Hodara, Busch, Kittlein & Kravetz (2001), Hodara, Busch & Kravetz (2000), Hodara, Suédrez & Kravetz (1997), Massoia (1961, 1971b), Massoia & Fornes (1965a), Pardinas (1993), Pardinas, Abba et al. (2004), Pardinas, Teta, Alvarado-Serrano et al. (2015), Pardinas, Teta, D'Elia et al. (2007), Pearson (1967), Polop & Busch (2010), Priotto & Polop (1997), Priotto & Steinmann (1999), Reig (1964, 1965), Rouaux et al. (2003), Suérez (1996), Suérez & Bonaventura (2001), Suarez & Kravetz (1998a, 1998b, 2001), Suarez et al. (2004), de Villafane (1981), de Villafane et al. (1973), Zuleta & Bilenca (1992), Zuleta et al. (1988).