The shrew is a fairly small animal belonging to the shrew family. This insectivore lives on almost all continents (except the northern ones), preferring to choose forest zones and tundra as its habitat. It is among the shrews that one can find the smallest and most voracious mammals - there are about 7 dozen species in this genus - almost two dozen of them live in Russia.
Appearance
These small animals are similar to ordinary mice - but, unlike them, they belong to the order of insectivores. And their body structure, upon closer examination, is also significantly different from that of a mouse - the shrew has a larger head and muzzle, elongated like a flexible proboscis (this structure of the muzzle allows the shrew to successfully sniff out prey). The shrew has tiny and very expressionless eyes - as well as small ears, almost invisible against the background of the fur.
The shrew is a fairly small animal, and is constantly in search of food, which is vital for it. Small animals are not able to retain heat, unlike larger ones, and they constantly need to fuel the metabolic processes that occur in a tiny body at breakneck speed. And all warm-blooded animals are guided by a general rule - the smaller the body size, the more food is required to maintain it.
As a rodent, the shrew is equipped with 32 teeth with very long incisors. What’s interesting is that this animal is born with a full set of teeth: its milk teeth are replaced in the embryonic period with full-fledged permanent fangs.
The body length of this animal reaches up to 10 cm (and this is a giant shrew!), and the tiny shrew does not grow more than 4 cm (excluding the tail). The entire animal weighs up to 4 grams, and the length of the tail is up to 6 cm maximum. The tail can be short and almost reaching the size of the body. On its sides there are holes that can secrete a musky secretion with a pungent odor - this is how the shrew protects itself from predators.
The shrew has velvety fur of high density - at the top the animal is colored in reddish-brownish shades, which allows it to camouflage well, and its abdomen is light.
Continuation of the family line
Species living in regions with temperate and cold climates are characterized by a seasonal pattern of reproduction. Tropical species “play weddings” all year round. Pregnancy in different species lasts from 17 to 32 days. Cubs are born naked and blind, but develop very quickly.
The common shrew begins to reproduce in the second year of life. The breeding season is in April. Typically, adult females produce 1 or 2 litters of 4-8 young and then die. By this time, adult males also die, so that at the end of summer immature young animals dominate the population.
The giant shrew, like the common shrew, is characterized by promiscuity: scientists recorded a case where a female mated with eight different males 278 times within two hours!
In some species, the young exhibit "caravan" behavior. Grown-up babies, leaving the nest, line up so that each one grabs the back of the body of the one in front with its teeth, and the very first one grabs its mother. Their grip is so tenacious that the entire caravan can be lifted off the ground if you only grab the female.
What does it eat?
In searching for food, the shrew is helped by a highly developed sense of smell and very sensitive hearing (even with the use of echolocation). The basis of her diet is animal food - this is understandable, because such proteins are the most high-calorie. The shrew feeds on everything it can catch with its needle-sharp teeth. Moreover, the amount of food that a shrew consumes per day can be several times greater than the entire animal itself.
A shrew (for example, its species is the tiny shrew) can feed an insane number of times throughout the day - more than a hundred - while eating every half hour.
Nutrition
The animal, despite its modest size, is extremely voracious, consuming twice its weight in food per day.
And she finds food by actively rummaging in the upper layers of the soil, which has the misfortune of greatly annoying avid gardeners and gardeners. But it’s better not to rush to get angry at neighbors like shrews, because animals can help get rid of many pests: caterpillars, weevils, leaf beetles, click beetles, chafers, mole crickets, and slugs.
Moreover, a shrew rarely catches the eye of a person, because it operates mainly at night, actively swarming in the garbage. The animal feeds on terrestrial invertebrates: snails, centipedes, spiders and earthworms.
In the forest floor, teeming with small animals where it lives, it is not difficult for it to obtain food during favorable periods. The shrew is also quite capable of eating bird droppings, carrion and plant seeds, which usually make up its winter diet.
When eating, the animal usually rests on all four paws, but in some cases, for example, when eating slippery worms or beetles, it can use its front paws to hold its prey.
Often in search of something edible, the shrew climbs trees, climbing the trunk, clinging to uneven bark with its paws in order to feast on the eggs of a nun butterfly or gypsy moth.
To get food, the shrew is capable of attacking even such large animals, in comparison with its size, as small rodents and frogs. And if he wins, he eats them almost entirely, leaving only the skins and bones of his victims.
Many frogs become prey for shrews during hibernation, and when the snow melts, only their thoroughly gnawed skeletons can be found on the forest floor.
Red Book and population
The population of different shrew species and its size varies significantly. For example, for Eurasia, the most common (and, accordingly, numerous) is the common shrew with a population of about 600 individuals per hectare. Naturally, the more food and places suitable for living are available, the greater the distribution density of the species. The small and tiny shrew and many other species have approximately the same habitat. Many American shrews are also characterized by densely populated habitats, which cover mainly forest and tundra zones.
There are also clearly localized species of this family - for example, the Caucasian shrew, which lives in the forests of the Caucasus, or the Kamchatka shrew, which lives on the coast of the Sea of Okhotsk and Kamchatka.
In this family, it is not so common to find very small or rare (especially if we are talking about a limited territory) species - although each country can boast of its rarity.
For example, only one species of shrew is listed in the Red Book of our country - the giant shrew. This rodent is indeed the largest representative of its genus and is classified as a rare species that is characterized by low numbers. The giant shrew lives in the forests of Primorye and is found in only a few places in this territory: the Lazovsky Nature Reserve, the Kedrovaya Pyad Nature Reserve, and Lake Khanka.
For the shrew and its protection, completely unoriginal measures are used, which mainly include the preservation of areas suitable for habitation. After all, it is important that even such a creature, which lives on the edge of the capabilities of warm-blooded animals, can survive.
Reproduction
Giant shrews are nonfertile animals. This fact is probably one of the reasons for the gradual extinction of the species. Females give only one offspring per year. Since giant shrews lead a secretive lifestyle, scientists to this day have not been able to determine the number of young individuals in the litter. What is known is that from two to four embryos are born in the womb of females. The question of how many babies are born remains a mystery. According to some data, the lifespan of such animals is only one and a half years.
It is noteworthy that during the entire period of study of the species, naturalists were not able to catch a single male giant shrew. Therefore, the conditions under which members of the species mate are unknown.
Natural enemies
The tiny little thing, foul-smelling and very evil, oddly enough, also has its enemies:
- small predators;
- predator birds;
- snakes and vipers;
- predatory fish;
- representatives of their own species;
- parasites.
It is interesting that when studying the common shrew, more than one and a half dozen species of various parasites and helminths were found in its representatives. One individual could contain more than 500 worms.
Usually the shrew is not bothered by people - although sometimes they can suffer in the event of mass persecution of rodents. Most often, people harm it indirectly - through changes in the habitat (development, deforestation, etc.).
Ways to deal with shrews
Digging through many-meter-long tunnels in search of food, the shrew spoils not only vegetable plants, but also lawns and front gardens. This cannot be allowed.
- Careful and deep digging of the site.
- Pour crushed (not finely) eggshells into the hole.
- Low-growing marigolds and legumes planted in rows are effective. Additionally, garlic or onions are planted around the perimeter of the site - this is not something that shrews eat, their smell is good at “daring off” the animals.
- Using traps with baits that are used for mice.
- They install a repeller, which is a tin turntable that constantly creates noise. Shrews really do not like such “noise performances” and move away from such places. Similar repellers have appeared on sale, only electric ones.
- A simpler repeller that creates noise and rumble - cut-off tin cans or plastic bottles are attached to driven pegs 1 m high.
- A method that allows you to block access to the site for small pests: dig sheets of iron or slate around the perimeter of the site to a depth of 1.5 meters. The shrew doesn’t burrow that deep, so it certainly won’t be able to overcome such an obstacle.
- Tornado ultrasonic devices have proven themselves to be excellent; they are absolutely safe; their operating principle is low-frequency vibrations that are not tolerated by the shrew family.
Video
Interesting Facts
One interesting fact is known about the shrew. It is due to the fact that its smallest species live precisely where the harshest living conditions occur - the tundra, highlands, Siberia - and, logically, should strive for more favorable territories. Moreover, the size of the animal can be smaller the further north it lives - which contradicts Bergman’s rule, according to which the size of individuals should change upward due to cold. Many shrews in the northern regions are able to reduce the size of their internal organs during the winter in order to reduce heat loss.
Habitat
Giant shrews prefer to settle in wooded areas filled with coniferous and broad-leaved trees. Such animals dig holes on slopes that are in close proximity to water sources. In particular, these animals build their homes in river valleys. In general, shrews try to stick to damp, but not swampy areas.
Currently, the most numerous populations are observed in the southern part of Primorsky Krai. Giant shrews are found in areas located between the valleys of the Kamenka and Serebryanka rivers. Outside the domestic latitudes, representatives of the species were repeatedly caught in China and Korea.
Shrew lifestyle
These animals lead a solitary lifestyle. They are active mainly at night, about 2 hours before sunset.
Shrews can make moves in soft soil using their paws and proboscis. But most often they move on the surface. They overcome winter thanks to developed physiological characteristics: in late autumn, their body size and weight decrease. These processes affect all internal organs, including the brain.
In spring, the body size of shrews increases sharply. These small animals are characterized by an increased level of metabolism.
The common shrew consumes an amount of food per day that is 150% of its weight.
They easily deal with ground beetles, swimming beetles, large pine borers and other insects. Shrews can also attack voles that are larger than them. The shrew eats insects up to 35 centimeters in size instantly.
Shrews have predatory tendencies.
The shrew kills a lizard measuring 7 centimeters in just 4 seconds. Larger lizards have to make multiple attacks. At one time, the shrew eats up to 3 large bronze shrew larvae, each of which weighs about 3 grams.
There are no predators that specialize exclusively in eating shrews. On occasion, the shrew is attacked by predatory mammals and day and night birds. But predators are reluctant to attack shrews because they have a strong musky odor. One of the main enemies among mammals is the sable.
Notes
- Wilson DE & Reeder DM (eds).
Mammal Species of the World. — 3rd ed. - Johns Hopkins University Press[en], 2005. - Vol. 1. - P. 743. - ISBN 0-8018-8221-4. OCLC 62265494. - Sokolov V. E.
Five-language dictionary of animal names. Mammals. Latin, Russian, English, German, French. / under the general editorship of academician. V. E. Sokolova. - M.: Rus. lang., 1984. - pp. 38-39. — 352 p. — 10,000 copies. - ↑ 12345678910111213141516171819202122232425262728293031
Complete illustrated encyclopedia. "Mammals" Book. 2 = The New Encyclopedia of Mammals / ed. D. MacDonald. - M.: Omega, 2007. - P. 439. - 3000 copies. — ISBN 978-5-465-01346-8.
The role of shrews in the study of evolution
On our planet, ice ages occurred several times, then they were replaced by periods of warming. During the Ice Age, animals migrated following the outgoing heat, and with the advent of warming, they returned to their former habitats. A shrew helped find out how this happened.
For the winter, shrews make a reserve from the seeds of coniferous trees and, less commonly, mushrooms.
The technique for tracking the return paths of animals and people is based on studying the chromosome set of shrews. In each animal species, the number of chromosomes is basically constant, but this rule does not apply to the shrew. Each population of shrews has its own set of chromosomes.
By studying differences in chromosomes in shrews, scientists were able to reconstruct the history of evolution within Eurasia. The research was carried out among shrews living in Western Siberia.
When the weather worsened, their habitat narrowed, and they survived only in the mountainous regions of the Southern Urals, the Sayans and Altai. With the decrease in the distribution area of shrews, their chromosomal diversity has decreased. At the same time, a characteristic set of chromosomes was determined for each habitat. Thanks to which modern science has been able to recognize from which places certain species originated.
Even before the ice age, about 18 thousand years ago, these animals lived everywhere, they even inhabited the forests of the Arctic.
When the ice retreated, forests began to grow, and with them the number of forest animals, including shrews, increased. They began to settle further north. Moreover, each population differed by one chromosomal change. Having studied these changes, scientists have figured out the ways of their return and settlement throughout Siberia.
The advancement of shrews occurred in three directions. Shrews, living during the Ice Age in the Sayan Mountains and Altai, spread into Eastern Siberia. South Ural shrews populated the Ural mountains in a northern direction. Rodents from the eastern part of the Urals settled in the West Siberian Plain. In the east, shrews from the Sayan and Altai and from the eastern part of the Urals met, and a new race was formed.
This technique has so far been developed only for shrews, but it makes it possible to track the movements of other species of animals and even people, since they all moved behind the retreating ice.
Most predators, with the exception of owls, do not eat shrews, which is due to their unpleasant, pungent odor.
