Growth, development and maintenance of American water shrews (Sorex palustris) in captivity

Abstract

This paper documents a cost-effective method for the long-term housing and maintenance of water shrews. Wild-caught American water shrews (Sorex palustris) were successfully maintained in this set up for up to 2 years, suggesting a maximum lifespan of 28 months for this species in captivity. In addition, we describe the postnatal growth and development of S. palustris based on data collected from two litters born in captivity, together with corresponding changes in maternal mass over the gestational and postpartum periods. Minimum gestation for this species is 21 days with neonatal mass at birth averaging 0.42 g (n = 3). This study recorded one of the fastest growth rates to date for any Sorex shrew (0.51 g/day), with body mass beginning to plateau by 23 days of age. During the last two weeks of pregnancy, body mass of one pregnant shrew increased from 16.0 to 22.8 g (0.45 g/day). Maternal mass quickly dropped by 5 to 7 g following birth. However, maternal body mass then gradually increased by ca. 20% during the 24 to 27 day lactation period, despite a >30 fold increase in litter mass over this same interval. Exposure of young to water was initiated on day 25 with only surface swimming occurring on this day. All shrews were observed diving the following day, and appeared to be fully proficient divers by 40 to 45 days of age.