The Canarian shrew is very well adapted to the hot and dry conditions of the lava fields. In the malpaís, it uses lava tubes which provide a small amount of protection from the weather. This enables the Canarian shrew to survive even when surface temperatures approach 60 degrees Celsius (1).
The Canarian shrew feeds mainly on insects and snails within the lava tubes, but its diet varies between different populations. On Montaña Clara Island, in addition to sand fleas and seabird corpses, the Canarian shrew’s main source of food is the Atlantic lizard (Gallotia atlantica), a small lizard weighing less than seven grams (4).
Unusually for a mammal, the Canarian shrew uses venom to immobilise its prey. The effects on one its prey species, the Atlantic lizard, have been studied extensively (4).
When the Canarian shrew encounters an Atlantic lizard, it quickly attacks by jumping onto the lizardand biting its neck. The bite delivers neurotoxic venom, which very quickly immobilises the lizard, and paralyses it for 24 hours or longer. The Canarian shrew is capable of consuming the entire lizard, including its legs and innards, in less than an hour. However, if it has recently eaten, the Canarian shrew will carry away its prey and hide it among rocks to return to later. This is an important strategy in a challenging environment with unreliable resources (4).
The Canarian shrew is very secretive, and spends much of the day hidden under rocks, in a scratched-out cavity. However, it is capable of very quick and agile movement should it be disturbed. Surprisingly, the Canarian shrew is very quiet, with hardly any vocalisations observed from any experimentally studied specimens. This is in contrast to the closely related greater white-toothed shrew (Crocidura russula), which vocalises on many occasions (7).
Unlike other mammals of a similar size, the Canarian shrew produces small litters, usually of around one to three young. The gestation period is usually about 32 days (2) (7). The young Canarian shrew is born naked and blind and weighs approximately one gram. After 11 to 12 days, the young can walk, and it will continue to suckle up to about 23 days old. A Canarian shrew captured from the wild lived for five years in captivity (2).