A primarily nocturnal species (2) (4) (7), the southern short-tailed shrew is rarely seen during daylight hours except on cloudy, overcast days (7). This highly active species (2) has a poor sense of smell and extremely poor eyesight, and so relies mostly on its acute hearing and highly developed sense of touch to navigate, avoid predators and seek out prey (4).
The southern short-tailed shrew builds runways under leaf litter or within loose soil, and also uses the burrows and runways of other small mammals (4) (7). Within its runway system, this species creates shallow nests for resting, and although the southern short-tailed shrew is usually a solitary species (4), multiple individuals may make use of a common burrow system (1) (4). Larger nests for rearing young are often located under rotting vegetation such as logs and stumps (1) (4) (5) (7), or in a deeper burrow system which may be more than 30 centimetres below the soil surface (4) (5). These larger nests can be between 10 and 20 centimetres in diameter (4) (7), and are made of shredded grass, roots, leaves and other plant fibres (4) (5) (7).
Shrews have the highest metabolic rates of any North American mammals, with a pulse rate of about 700 beats per minute (7). Although some reports suggest that the southern short-tailed shrew needs to eat its own body weight in food each day (4) (7), more recent studies have shown that it requires less than half that (4). However, the southern short-tailed shrew still has a voracious appetite (4), and is constantly on the prowl for food when active (7).
Insects make up about 92 percent of the southern short-tailed shrew’s diet (9), but this species also eats other invertebrates including worms, snails, slugs, spiders and centipedes (2) (3) (4) (5) (7). Live snails are often collected and stashed away in a burrow as a food supply for the winter (1) (4). In addition, the southern short-tailed shrew eats fungi and plant material (1) (3) (5) (9), such as nuts and berries (4), and has been reported to feed on turtle eggs in Florida (5). Interestingly, this species is also known to eat small vertebrates (1) (2) (3) (4) (5) (7), which it subdues using toxic saliva secreted by specially modified salivary glands (3) (4). This saliva is capable of paralysing and killing prey the size of a mouse within three to five minutes (7).
Despite its toxic saliva, the southern short-tailed shrew is still palatable to many predators, including snakes, owls, hawks, foxes and weasels (2) (4) (5) (7). However, as a way of repelling predators, and also as a way of communicating an individual’s breeding status or defending its territory, the southern short-tailed shrew secretes a pungent odour from glands located on its rump and flanks (7).
The timing of breeding in the southern short-tailed shrew varies depending on location (1), but generally lasts from late winter or early spring to late summer (1) (7). In Texas and Arkansas, it is known to start as early as February (1) (4), and it is thought that individuals living at lower latitudes may have a longer breeding season (5). Reproductive peaks are often seen in spring (3) and late summer (3) (7).
After a gestation period of 21 to 30 days (1) (4) (7), the female southern short-tailed shrew gives birth to a litter of between 3 and 10 young (4) (7), with the average litter size being 5 to 7 young (1) (4). It has been noted that smaller litters tend to be produced between March and July, and larger litters between September and November (5). Female southern short-tailed shrews can produce three or more litters per year (1) (3) (4) (7). The young shrews leave the nest after three or four weeks (4) (7), and become mature at about three months of age (4). The southern short-tailed shrew is thought to have a maximum lifespan of two years (1) (7).