Demography of an insular endemic rodent, Pperomyscus maniculatus santacruzae, on Santa Cruz Island

摘要

We measured density, body mass, reproduction, and survival of endemic deer mice (Peromyscus maniculatus santacruzae) in five habitats on Santa Cruz Island to assess how deer mice may be affected by vegetational changes following removal of feral sheep. Demography of deer mice varied among habitats, suggesting that habitat quality varied as well. Deer mice were abundant in habitats dominated by woody vegetation (island chaparral, oak woodland, coastal sage scrub), but rare or absent from habitats dominated by herbaceous vegetation (grassland, fennelgrassland). Density, body mass, reproduction, and survival did not differ among habitats dominated by woody vegetation, indicating that these habitats are all of similar, good quality for deer mice. Removal of feral sheep has resulted in invasion of grasslands by shrubs and increase in woody vegetation in other communities, which likely will benefit deer mice. Invasion of grasslands by fennel should have little effect on deer mice because both grassland and fennel-grassland were poor quality habitats.