The Northern Short Tailed Shrew.

The Northern Short Tailed Shrew.

The northern short-tailed shrew is one of the only two venomous mammals the other is the Duck Billed Platypus. The northern short tailed shrews scientific name in Blarina brevicauda. The Northern Short Tailed Shrew is the largest shrew in the genus Blarina. The word genus refers to a taxonomic classification that ranks above species and below family. The Northern Short Tailed Shrew has a total length of 108 to 140 mm (4.3 to 5.5 in) with a tail length of 18 to 32 mm (0.7 to 1.3 in). The shrew also weighs about 15 to 30 g (0.5 to 1.1 oz). The Northern Short Tailed Shrew's fur is thick and velvety. The Shrew's fur is also black, brownish black, or silvery gray. The Northern Short Tailed Shrew's sense of smell is thought to be poor, and their eyes are degenerated and vision is thought to be limited to the amount of light in the area. but the Northern Short Tailed Shrew compensates by using echolocation and a having good sense of touch. The Northern Short Tailed Shrew has slight sexual dimorphism in size, with the male being slightly larger than the female. This means that the male shrews have are sligthly larger than the females.

The Northern Short Tailed Shrew consumes up to three times its weight in food each day. It eats small amounts of seeds and fungi although it is mostly carnivorous. The Northern Short Tailed Shrew eats insects, earthworms, voles, snails and other shrews. The Northern Short Tailed Shrew consumes vertebrates more often than other shrews do. The shrew mostly forages within a few hours after sunset, though the shrew is also active during cloudy days. One study found this shrew stores 87% of the prey it catches, while 9% is eaten immediately and 4% is left where it was killed. The Northern Short Tailed Shrew Has compartments in it's burrow which it will use to store it's food to eat at a later time.

The saliva of the northern short-tailed shrew contains a kallikrein-like protease, used to paralyze and its prey. The Northern Short Tailed Shrew's toxin is strong enough to kill small animals, up to sizes somewhat larger than the shrew itself.The Northern Short Tailed Shrew's poison is also strong enough to result in painful bites to humans who attempt to handle the shrew. The shrew's venom is secreted from sub maxillary glands, through a duct which opens at the base of the lower incisors which are the narrow edged teeth at the front of the shrew's jaw. The Shrew's venomous saliva flows along the groove formed by the two incisors, and into the prey when it bites it. The toxin of the Northern Short Tailed Shrew's is similar to the one used by the Mexican beaded lizard (Heloderma horridum).

The shrew's ability to consume almost anything it can catch allows the Northern Short Tailed Shrew to survive cold winters. The Northern Short Tailed Shrew mostly lives in coldish temperate regions which means that it must get lots energy to survive. Where The Northern Short Tailed Shrew's thermoneutral zone ( The temperature that the shrew prefers) range from 25 degrees Celsius (77 degrees Fahrenheit) to 33 degrees Celsius ( 91.4 degrees Fahrenheit). Although the Northern Short Tailed Shrew can easily withstand temperatures of 33 degrees Celsius ( 91.4 degrees Fahrenheit) 35 degrees Celsius ( 95 degrees Fahrenheit) and higher are lethal to the shrew. The Northern Short Tailed Shrew is primarily nocturnal although the degree of nocturnality changes with the season. During the colder winter the shrew has more out-of-burrow activity earlier in the evening, but are active later in the night during the summer. This has been tested with Northern Short Tailed Shrews in a laboratory and the study also showed that this was most likely due to solar radiation and changing daily temperatures, and it allows the shrews to minimize the energy needed to sustain themselves. The Northern Short Tailed Shrew also have other adaptations in winter including lining there nest which helps the shrew in conserving heat, the caching or saving of food in case of prey shortages and more.

Both disturbed and undisturbed habitats are used by the Northern Short Tailed Shrew, including grasslands, old fields, marshy areas, deciduous and coniferous forests, and household gardens. Though the preferred habitats are ones that are moist with leaf litter or thick plant cover. The northern short-tailed shrew has a high mortality rate, though it attempts to escape predation by remaining hidden under vegetation, soil, leaf litter, or snow. But only 6% of the shrews survived to the next year, and a winter mortality rate of 90% has been recorded. possibly due to cold stress. The Northern Short Tailed Shrew is eaten by many predators including trout, snakes, canids, cats, mustelids, skunks, raccoons, and opossums though some carnivores are deterred by the odor produced by the shrew's scent glands. The Northern Short Tailed Shrew has 3 scent glands which it uses to mark it's territory. The shrew is found throughout central and eastern North America, from southern Saskatchewan to Atlantic Canada and south to northern Arkansas and Georgia. It is the most common shrew in the Great Lakes region. Population densities usually range from two to 12 shrews per acre, but rarely exceed 20 shrews per acre. The typical home range of a shrew is 6.17763 acres. And sometimes overlaps slightly with the ranges of other shrews.

Other shrews spend more time above ground than The Northern Short Tailed Shrew, which prefers to tunnel along below ground. The Northern Short Tailed Shrew will have periods of frenzied activity, lasting around five minutes which are followed by longer periods of resting, with the total active time of only 16% of a 24-hour day (3.84 hours). This shrew is capable of digging at a slow rate of 2.5 centimeters per minute, in between resting. Normally The Northern Short Tailed Shrew exhibits several aggressive displays to ward off other shrews of the same species when they encounters each other. tests show that pairs of shrews which were put into a cage simultaneously lived for less than four months before one killed the other, and a new shrew placed in a cage containing an already established shrew will almost always be killed within a few hours.

Mating occurs from March through September. Six to eight shrews are commonly born in a liter and two litters are normally born per season. The young, which were born hairless and blind and weighing less than a gram, can become sexually mature in as soon as 2–3 months those born in the spring mature more quickly than those born late in the season, and may themselves reproduce in the same year that they were born.