have a higher exposure to parasites. Diet and prey Masked shrews are opportunistic generalists. They eat insects, worms, snails, small rodents, salamanders, and seeds. Due to its high metabolism, the masked shrew can eat three times its weight a day. The shrew has to eat almost constantly, because they can only survive a few hours without food. Their metabolism drops when they are at rest. McCay and colleagues (1997) found a higher abundance of masked shrews in non-irrigated forests due to a higher availability of larval insects, which is the preferred food source of the masked shrew. Masked shrews chose Lepidoptera larva over other food sources. Behavior This animal is active day and night year-round. Masked shrews can be nocturnal or diurnal depending on the weather. Doucet and colleagues (1974) showed that rain increases the nocturnal activity of the masked shrew, while cloud cover increases day and night activity. It digs tunnels but also uses tunnels created by other small mammals. It uses dry grass to make nests in these tunnels. It can make high frequency pulses and has lateral scent glands. The home range of the masked shrew depends on availability of food, but it is on average 0.55 hectare. It has a low tolerance for other shrews in its home range. Merritt and colleagues (1995) found that its mass declined by half from summer to winter and non-shivering heat production, energy conservation, and reduced body mass. Reproduction Masked shrews living at high latitudes are born in late spring and summer, reach adult size by the time they leave their nests, and complete their life cycle within a year. They are born during spring or summer, remain immature in winter, and breed the following spring. Masked shrews breed from May to September. Females have one litter of 6 to 7 young during the breeding season. The young are born hairless and clawless and have translucent abdominal walls. Body mass increases and peaks at twenty days, then decreases when the young leave the nest after about 27 days. Masked shrews have a high chance of mortality during their first two months of life and most die during the first year. Masked shrews become sexually mature at two months, but wait until their first spring to breed. References Sources Hutterer, R. (16 November 2005). Wilson, Don E., and Reeder, DeeAnn M.. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns