Seasonality in reproduction, age structure and density of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in a Brazilian cerrado

Abstract

The temporal pattern of reproduction and its consequences for age structure and density were investigated in a population of the gracile mouse opossum Gracilinanus microtarsus in south-eastern Brazil. Individuals of G. microtarsus were monitored through capture–mark–recapture methods from August 2000 to February 2003 in a remnant of cerradão, a forest-like physiognomy of the highly seasonal cerrado biome. The temporal pattern of reproduction of the population studied was highly seasonal with rearing of the offspring occurring in the first half of the warm-wet season, when the abundance of food resources – primarily insects – in the cerrado is high. Shortly after reproduction, the density of adults decreased sharply, possibly because of high post-mating mortality, leading to a gradual replacement of adults by their offspring in the following months and little overlap of generations. Our data suggest that climatic and environmental factors affect the onset of reproduction and interact with endogenous factors that decrease post-mating survival to produce the observed pattern of seasonal variation in age structure and density. It is suggested that the dynamics of populations of G. microtarsus may be driven primarily by food limitation and that long-term studies are needed to understand its feedback structure.

Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado

“…Gracilinanus microtarsus Wagner 1842 is a small, solitary, arboreal and nocturnal didelphid marsupial that inhabits cerrado (savanna) and the Atlantic forest of south-eastern Brazil (Costa et al 2003, Martins et al 2006a). This species shows sexual size dimorphism, with adult males (30-45 g) being larger than adult females (20-30 g) (Martins et al 2006a) and occurs at high densities in the cerrado (Martins et al 2006a).…”

Artificial nests as an alternative to studies of arboreal small mammal populations: a five-year study in the Atlantic Forest, Brazil

“…data). If M. incanus is indeed semelparous (MARTINS et al 2006, LEINER et al 2008, adult males die just after reproduction, but there are already weaned and independent juveniles present in the area. Detectability varied between sampling methods, a fact occasionally recognized in small mammal studies such as EMMONS (1996) andVOSS et al (2001), which indicates that no single methodology is effective for recording the presence of all the species in an area.…”

Pequenos mamíferos não-voadores do Planalto Atlântico de São Paulo: identificação, história natural e ameaças

“…Brucepattersonius soricinus é considerada endêmica da Floresta Atlântica, com distribuição restrita ao centro-leste e sudeste do Estado de São Paulo (Hershkovitz 1998, Reis et al 2006.…”

“…Calomys tener ocorre no norte da Argentina, leste da Bolívia e Brasil (Wilson e Reeder 2005, Reis et al 2006. No Brasil é amplamente distribuída, com registros para os Estados de Mato Grosso, Mato Grosso do Sul, Goiás, Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro e São Paulo (Vieira e Baumgarten 1995, Fagundes et al 2000, Reis et al 2006.…”

“…No Brasil é amplamente distribuída, com registros para os Estados de Mato Grosso, Mato Grosso do Sul, Goiás, Bahia, Minas Gerais, Espírito Santo, Rio de Janeiro e São Paulo (Vieira e Baumgarten 1995, Fagundes et al 2000, Reis et al 2006. Comum no bioma Cerrado (Carmingnotto 2004) ocorre também em áreas de transição entre o Cerrado e a Caatinga, e entre o Cerrado e os dois biomas florestais do Brasil, Amazônia e Mata Atlântica (Fagundes et al 2000, Carmignotto 2004.…”