The northern short-tailed shrew (Blarina brevicauda) is the largest shrew in the genus Blarina, and is found in the northeastern region of North America. This species is a highly active and voracious insectivore and is present in various habitats. It should be noted that she is one of the few venomous mammals. The specific epithet, brevicauda, is a combination of the Latin brevis and equine, which means "short tail". Blarina brevicauda is a red-toothed shrew, one of three or four species (depending on the organ) in the genus Blarina. It was previously thought to be a sister subspecies of the southern short-tailed shrew (carolinensis blarina). This species has been subdivided into eleven subspecies based on morphological characteristics, which are grouped into two semi-species: brevicauda and talpoides. These groups were reflected by the molecular taxonomy of the study of mitochondrial cytochrome b sequences. Two groups of subspecies are believed to have been preserved by isolated Pleistocene glaciers.
This shrew has a total length of 108 to 140 mm (4.3 to 5.5 in), of which 18 to 32 mm (0.7 to 1.3 in) with a tail, and weighs 15 to 30 grams (0.5 up to 1.1 ounces). The northern short-tailed shrew exhibits slight sexual dimorphism in size; males are slightly larger than females. The dorsal fur is thick and velvety, and may be black, brown-black, or silver-gray, with the belly fur being slightly lighter and grayer. The northern short-tailed shrew sheds from summer coats, which are shorter and paler than winter coats in October and November, and vice versa in February and July. The tail is rather short, accounting for less than 25% of the total length. Dental formula 2-2 / 1-1, C 1-1 / 1-1, P 3-3 / 1-1, M 3 - 3 / 3-3 = 14/18 = 32. Three well-developed odor glands are present, one on each side of the animal and one abdominal. Smell can be used to mark an area, although shrews are considered poor in terms of odor.
Most of the remains of B. brevicauda are from the Pleistocene, although one find from the end of the Pliocene has been tentatively assigned to this species. The species is believed to have originated in the middle or late Pliocene. The brevicauda subspecies appeared later.
This shrew is found throughout central and eastern North America, from southern Saskatchewan on the Atlantic coast of Canada and south to Nebraska and Georgia. This is probably the most common shrew in the Great Lakes region. Population densities typically range from 5-30 shrews / ha (2-12 per acre), but rarely exceed 200 per ha (80 acres). The typical house range of the shrew is 2.5 hectares, and may overlap slightly with the ranges of other shrews. Both disturbed and undisturbed habitats are used by the northern short-tailed shrew, including meadows, old deposits, fencerows, marshy areas, deciduous and coniferous forests, and home gardens, although the preferred habitats are wet with a decent amount of leaf litter or thick vegetation cover. Burned forests are not quickly colonized by B. brevicauda, and shrews quickly leave clear felling.
The northern short-tailed shrew consumes three times its weight in food every day. It eats small amounts of underground mushrooms and seeds, although it is mostly carnivorous. It prefers insects, worms, voles, snails, and other shrews for the bulk of its diet, although salamanders and mice are also eaten. This shrew consumes vertebrates more often than other shrews. The northern short-tailed shrew mainly feeds for several hours after sunset, although it is also active during cloudy days. Due to high evaporation and water loss, the Northern Short-tailed shrew will require access to a water source, although it also draws water from its diet. The northern short-tailed shrew often stores food, especially in autumn and winter, or when it is taken in abundance. One study found that 87% of the prey she catches is stored, 9% is eaten right away and 4% remains where she was killed.
The saliva of the northern short-tailed shrew contains kallikrein, a protease used to paralyze and subdue its prey. The toxin is strong enough to kill small animals, up to a size slightly larger than the shrew itself, and the results of bites from people trying to control the shrew are painful. Poisonous saliva is secreted from the submandibular gland, through the duct at the base below the incisors, where saliva flows along the groove formed by the two incisors, and into the prey. This toxin is very similar in structure to the venom used by the Mexican lizard (Heloderma horridum), but developed independently, but from the same precursor protein. One component of the venom, a peptide called Soricidin, has been patented and is currently being researched in Canada for pain control and as a cancer drug. Another component is currently being studied in Japan as an antihypertensive agent.
The sense of smell is considered weak and the eyes are degenerate and vision is believed to be limited to detecting light, but the shrew compensates for this with echolocation and a subtle sense of touch.
Its ability to consume almost anything it can catch allows the Northern Short-tailed Shrew to survive the cold winters of temperate regions. The thermoneutral zone of this species is between 25 and 33 degrees Celsius, which means that no additional energy must be expended on animals to maintain their body temperature (which averages 38-38.5 degrees Celsius) when the ambient temperature is within this range. Food consumption is 43% higher in winter than in summer, as a shrew must increase its metabolic rate to maintain its body temperature in cold conditions. Temperatures no higher than 35 degrees Celsius are fatal for this obstinate. A study of captive shrews found that if they were mostly nocturnal, the degree of nocturnality changed from season to season. That is, during the colder winter months the shrews exhibited more outside-burrow activity in the early evening, but were active later at night during the summer. The study found that this seasonal was associated with solar radiation and changes in daily temperatures, and that it minimized the energy shrews needed for thermoregulation. Other changes include the creation of a lined nest in winter, which helps keep the shrew warm, storing food in the event of a shortage of prey, feeding below fallen leaves or snow where temperatures are milder, and reducing activity during colder periods. Along with these behavioral adaptations, the Northern short-tailed shrew enhances its ability to generate heat during the winter nonshivering thermogenesis in brown adipose tissue.
Other shrews spend more time above ground than the northern short-tailed shrew, which prefers to tunnel along underground, through fallen leaves, or at the snow / ground interface. Attacks of frenzied activity, lasting about five minutes, are followed by long periods of rest, with total active time accounting for only 16% of a 24-hour workday. This animal is capable of digging at a speed of 2.5 cm per minute between rest periods.
The northern short-tailed shrew builds a nest up to 20 centimeters (8 inches) in diameter, underground or under a log, and lines it with the leaves or fur of the Meadow vole (Microtus pennsylvanicus). This nest is kept clean with waste stored outside the nest in the restroom area. Other parts of the burrow of the system are used to store food.
Usually solitary, B. brevicauda has several aggressive displays and vocalizations to ward off other members of the species when encounters occur. A pair of shrews introduced into a cage coexisted simultaneously for less than four months before one killed the other, and a new shrew placed in a cage containing an already established shrew is killed within a few hours.
Mating takes place from March to September, although most births occur sooner or later during this period. V. brevicauda is illegible. The male shrew, when observed in captivity, made clicking sounds while courting the female. During copulation, the male and female are linked together, and the female drags the male along with her. Pregnancy lasts 21-22 days, after which 4-7 young individuals are born, which are fed for up to 25 days. Two litters per season are typical, although three are possible. The female strengthens the nest when the young are nursing, and is also more active to support her with increased nutritional needs. Young ones who are born naked and blind, weighing less than a gram, can become sexually mature in the shortest 2-3 months. Those born in the spring are mature faster than those born at the end of the season and can themselves reproduce in the same year that they were born. In juveniles, the coat is pale and very similar to that of adults in summer, and molted when the young reach adult size.
The northern short-tailed shrew has a high mortality rate, although attempts to escape predation the rest are hidden under vegetation, soil, forest floor, or snow, in the study, only 6% of the marked group of shrews survived until the following year, and 90% mortality was not recorded in winter probably due to the stress of the cold. This shrew is consumed by many predators: trout, snakes, birds of prey, canines, cats, mustelids, skunks, raccoons, and possums, although mammalian predators are likely to be restrained by the musky odor produced by the odor glands of the shrew.
The northern short-tailed shrew is considered the species of least concern on the IUCN Red List as it is widespread, abundant, and its population is not declining.
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- First online 28 November 2009
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Notes on my hobbies
- Recent Entries
Travel to the North. Arctic Skuas
After a trip to the North, I came to my senses, figured out a little with the work and even slightly systematized the photographs taken. I will try to post a new post at least once a week, I will show the village of Dalnie Zelentsy and the nature of the Kola North - the tundra, the coast of the Barents Sea and some inhabitants of the protected islands.
I'll start with the robber birds, the short-tailed skuas. In an informative format, so that readers do not just see the photos, but learn something new about the birds of the North.
Short-headed skuas are true tundra birds. They nest in the tundra and on the coasts of the Arctic seas in both hemispheres. The habitat of birds in Russia:
According to their family ties, skuas are gulls. However, they differ from them so significantly that they are distinguished into a separate family. There are four species of skuas in the Murmansk region - large, short-tailed, long-tailed and medium skuas. The first three I was lucky enough to see (and shoot a little), but the middle one was not caught.
Skuas are predators, especially during nesting time, when they live in the tundra and may not be associated with water bodies at all. For the rest of the year, they wander alone or in flocks along the seas or oceanic coasts of the world, where they live mainly as seafood, indiscriminately eating everything that comes across - from crustaceans, molluscs, worms and fish to the meat and entrails of dead large marine animals. Skuas often hunt for robbery, chasing gulls, terns and forcing them to abandon their prey.
4. Skua's nest is a common hole in the ground where a bird lays two eggs:
5. Bird on the nest:
6. In Arctic Skuas, some of the birds are dark and some are white-bellied:
I photographed two pairs of skuas and both the female was dark and the male was light. However, the color of plumage does not depend on the sex of the birds; moreover, the ratio of dark and light birds depends on the region. For example, the dominance or predominance of dark birds has been noted in Iceland, the Faroe Islands, western Greenland, Labrador and the Commanders. An approximately equal ratio of dark and light morphs is characteristic of the Solovetsky Islands, Kamchatka, and the Kola Peninsula. In northeastern Greenland, Spitsbergen, Jan Mayen, Bear Island, Alaska, Kolguev Peninsula, Novaya Zemlya and throughout the tundra strip of Siberia, birds of light morph make up the overwhelming majority, and in some places dark morph is not found at all.
8. On days when the wind blows from the tundra on the coast and it gets much warmer, blood-sucking insects pester not only people, but also skuas:
9. Skuas violently drive away all birds of prey from their nest, including other skuas. They boldly attack a person, flying at him on low level flight and turning him aside only in the immediate vicinity:
To be honest, under such a psychological attack, I don't want to be near the skuas at all. According to the literature, Arctic Skuas, when attacking, do not hit a person, however, I did not check this statement, and filmed the birds from a decent distance from the nest.
The behavior of the Arctic Skua as a person approaches the nest differs from that of other skuas. The birds either attack from the air, then take them away from the nest, flapping their wings and screaming loudly - thereby achieving the desired effect, because being near a bird's nest is simply unbearable!
12. And finally, the shot that I like the most:
When preparing the note, the text of the book "Birds of the Tundra" by V.K. Ryabitsev was used
Table: short-tailed skink short-tailed classification
|View||Short-tailed skink (Latin Tiliqua rugosa)|
|Area||Steppes and deserts of Australia (except for the center and coasts)|
|Dimensions (edit)||30-36 cm with a mass of about 1 kg|
|The number and position of the species||Numerous, Least Concern|
Shorttail or short-tailed skink (Latin Tiliqua rugosa) is a large reptile from the genus of gigantic lizards that lives in the hot regions of Australia. Like many other representatives of the Australian fauna, these reptiles have a number of unique features that set them apart from their relatives in the family.
The body of the short-tail is rather dense and massive, slightly flattened on the sides. The head has a pronounced triangular shape with a slightly blunt nose. Feet not proportionally short, but powerful enough. The tail, as you might guess, is very short and just as tight. The length of the body from the tip of the nose to the tip of the tail is about 30-36 cm, while the weight often reaches 1 kg. Such an uncharacteristic structure imposed certain restrictions on the mobility of Tiliqua rugosa: the lizard is too slow, inactive, and sometimes it seems that it is also lazy.
Dark blue stubby tail. Photo: Martin Lagerwey
The skin of the short-tailed skink is covered with thick convex scales, which give the lizard a noticeable resemblance to coniferous cones. Such a coating probably also performs a protective function - not every predator is able to bite through the natural armor of a shorttail.
In this picture, you can clearly see how thick the scales of the sleepy lizard are. Photo: Graham
The color, as a rule, does not have camouflage properties, depending on the subspecies, it ranges from dark blue or dark brown to light cream. The belly is several tones lighter, often light shades pass to the back in the form of irregular spots.
Tiliqua rugosa is an endemic species in Australia.They prefer an arid hot climate, therefore they live in steppes, deserts and semi-deserts, avoiding coastal regions with high rainfall. The area can be represented as a wide ring enveloping the entire continent, which does not include the central and coastal regions.
Hunting skinks, as a rule, begins with the last rays of the sun, although it is only a stretch to call it such, these slow lizards are mostly engaged in gathering. By nature, they are omnivorous, for obvious reasons, preference is given to plant foods and snails, even more clumsy than they themselves. They can also feast on carrion - there is not so much food in the deserts to be neglected. They very rarely hunt large insects.
Features of the
- Unusual tail. The tail of these lizards is so similar to the head that many predators simply fall into a stupor from just one species of two-headed monster. In addition, fat accumulates in the tail for wintering.
- Blue tongue. The tongue of the shorttail has a triangular shape, impressive size and color from bright blue to dark blue.
- Unusual defense. In case of danger, the blue-tongued lizard does not run away, instead it takes a threatening position, opens its mouth wide, puts out its tongue and, clicking it, makes rather loud sounds.
- Monogamy. An absolutely unique feature for reptiles, today science does not know other representatives of this class who would create pairs for life, take care of and participate in raising offspring, and form related colonies.
- Live birth. Tiliqua rugosa is one of the few lizards that does not lay eggs. There are from 1 to 4 pups in the litter, differing in very solid size.
A short-tailed skink in a threatening stance. Photo: Matt Summerville