Insectivores are notoriously shy, secretive, and active mammals. Their vision is not highly developed, therefore they rely mostly on their other senses, hearing, touch, and smell. Some species of moles and shrews depend on echolocation, the use of sound to navigate. Insectivores have various means of protection, the most obvious being nocturnal, subterranean, or aquatic habitats. Most seek cover in deep forests, holes, and tunnels deserted by other animals, under leaves, branches, stems, and roots of plants. Hedgehogs and certain tenrecs have spiny armor for protection.

Insectivores communicate in a wide variety of ways. Insectivore communication can be both interspecific (between dif-

Hedgehog Under Leaves
East African hedgehog (Erinaceus albiventris) in Nairobi, Kenya. (Photo by Animals Animals ©Bruce Davidson. Reproduced by permission.)

ferent species) and intraspecific (among members of the same species). Adult hedgehogs make hissing snorts when threatened, and young make birdlike whistles and quacks while in the nest. Solenodons emit a high frequency clicking sound similar to that of many Soricidae, which may serve an echolocation function. White-toothed shrews (Crocidura leucodon) emit metallic squeaks. Suncus murinus chirps and buzzes. Among many tenrecs, communication is tactile, with a few audible signals. Some insectivores mark territory with bodily secretions. Scent glands are used for communication between golden moles, especially between mothers and their offspring and between sexes during the mating season. When marking their territory, moonrats (Echinosorex gymnura) produce a foul smell reminiscent of rotten onions or ammonia from small anal glands. Suncus murinus, the musk shrew, emits a pungent odor from a gland located between its last rib and hip bone. The Haitian solenodon (Solenodon paradoxus), has scent glands located in its groin and armpits that secrete a goatlike odor.

The Haitian solenodon produces a venom in a gland located in the mandible (lower jaw) then squirts it through a channeled bottom incisor. The southern short-tailed shrew (Blarina carolinensis), the short-tailed shrew, and Elliot's short-tailed shrew (Blarina hylophaga) have submaxillary glands that secrete venom as well. The toxicity of their saliva allows these tiny mammals to attack prey larger than themselves as their bites immobilize their victims. It is also thought that shrews use their venom to immobilize their prey for consumption at a later time.

Most of the species belonging to Insectivora are nocturnal (active between dusk and dawn). Sclater's golden moles, however, are among those who are active day and night. They must keep moving in order to maintain their body temperature and they do so by digging almost non-stop. When they do sleep, they keep their bodies warm with involuntary muscle twitches. Many shrew species are active day and night as well, because their metabolism requires them to eat continuously. Hedgehogs located in cooler climates hibernate during the winter and some desert-dwellers estivate (go into torpor by lowering their body temperature and slowing their metabolism) during very hot weather. In the months preceding their hibernation, hedgehogs build up substantial fat reserves to see them through their "down" time. Tenrecs and hedgehogs for example, are known to go into a state of torpor when food gets scarce. The tenrec's heartbeat can drop to one beat every three minutes accompanied by a drop in body temperature.

In the wild, insectivores are, for the most part, solitary animals whose social life is limited, for the most part, to mating and rearing of offspring. When hedgehogs gather during the breeding season; the animals establish a hierarchy. When solenodons meet, there may be some initial scuffling but they eventually tolerate each other. Solenodons are among the more social species with the young remaining for long periods with their mother. The nomadic shrew moles travel in groups of up to 11. Small-eared shrews (Cryptotis), are known to be sociable, with several adults sharing a nest at the same time. Outside of mating season, many Insectivora species do not tolerate each other in the wild and become extremely aggressive and violent. When in captivity however, these same animals initially avoid each other or exhibit aggressive behavior but eventually learn to live together quite peacefully.

Fossorial insectivores—moles, desmans, and a few species of tenrecs and shrews—spend much of their time digging burrows and tunnels for food and shelter. Eastern moles (Scalo-pus aquaticus) found in Central and North America, dig up to 102 ft (31 m) per day. The short-tailed shrew digs tunnels through leaves, plant debris and snow. The yellow golden mole (Calcochloris obtusirostris) is nicknamed "sand swimmer" because of the way it tunnels through the sand at an impressive speed.

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