Etruscan shrew
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The Etruscan shrew (Suncus etruscus), also known as the Etruscan pygmy shrew, white-toothed pygmy shrew and Savi's pygmy shrew, is the smallest known extant mammal by mass, weighing only about Template:Cvt on average.<ref name=j2/><ref name=j1/><ref name=r1/><ref name= r2>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name= sc>Template:Cite journal</ref><ref name= Macdonald /> (The bumblebee bat is regarded as the smallest mammal by skull size and body length.<ref name=j2>Template:Cite journal</ref><ref name=j3/>)
The Etruscan shrew has a body length of about Template:Cvt excluding the tail. It is characterized by very rapid movements and a fast metabolism, eating about 1.5–2 times its own body weight per day. It feeds on various small vertebrates and invertebrates, mostly insects, and can hunt individuals of the same size as itself. These shrews prefer warm and damp climates and are widely distributed in the belt between 10° and 45°N latitude stretching from Europe and North Africa to Malaysia. They are also found in the Maltese islands, situated in the middle of the Mediterranean Sea.<ref name=iucn/><ref name=r1/> Although widespread and not threatened overall, they are generally uncommon and are endangered in some countries.
DescriptionEdit
The Etruscan shrew has a slender (not truncated) body, with a length between Template:Convert excluding the tail, which adds another Template:Convert.<ref name= Macdonald>Template:Cite book</ref> The body mass varies between Template:Convert<ref name=j3>Template:Cite journal</ref> and Template:Convert<ref name=j1/><ref name= Macdonald/> and is usually about Template:Convert.<ref name=j2/> In comparison, the related greater white-toothed shrew can be twice as long and weighs four to five times more.<ref name= Macdonald/> The head is relatively large, with a long, mobile proboscis, and the hind limbs are relatively small.<ref name=m>Suncus etruscus. White-toothed pygmy shrew University of Michigan, Museum of Zoology</ref> The ears are relatively large and protuberant.<ref name= Macdonald/> The Etruscan shrew has a very fast heart beating rate, up to 1511 beats/min (25 beats/s) and a relatively large heart muscle mass, 1.2% of body weight.<ref name=j2/> The fur color on the back and sides is pale brown, but is light gray on the stomach. The fur becomes denser and thicker from fall through the winter.<ref name= Macdonald/> The shrew usually has 30 teeth, but the 4th upper intermediate tooth is very small (rudimentary), and is absent in some individuals.<ref name=r2/> Near the mouth grow a dense array of short whiskers, which the shrew actively uses to search for prey, especially in the night.<ref name=sc/> Dimorphism in body features between males and females is absent.<ref name=m/>
ActivityEdit
Etruscan shrews live alone except during mating periods. Their lifespan is estimated at typically around two years, but with a large uncertainty.<ref name= Macdonald/><ref>Longevity Records. Table 1. Record Life Spans (years) of Mammals Template:Webarchive. Demogr.mpg.de. Retrieved 2013-03-21.</ref> They protect their territories by making chirping noises and signs of aggressiveness.<ref>Stone, R. David (1995) Eurasian insectivores and tree shrews: status survey and conservation action plan, IUCN, p. 30. Template:ISBN</ref> They tend to groom themselves constantly when not eating, and are always moving when awake and not hiding. The hiding periods are short, and typically last less than half an hour. Clicking sounds are heard when these shrews are moving, which cease when they rest.<ref name=m/> The shrews are more active during the night when they make long trips; during the day, they stay near the nest or in a hiding place.<ref name=r2/> They reach their maximum level of activity at dawn.<ref name=iucn/>
Due to its small size and consequent high surface-area-to-volume ratio, the Etruscan shrew is at a constant risk of hypothermia, and would quickly freeze to death if not for its extremely rapid metabolism. Its skeletal muscles contract at a rate of about 13 contractions/sec during respiration alone. In cold seasons and during shortages of food, the shrews lower their body temperatures down to about Template:Convert and enter a state of temporary hibernation to reduce energy consumption. Recovery from this state is accompanied by shivering at a frequency of 58 muscle contractions/sec.<ref name=j2/> This induces heating at a rate of up to 0.83 °C/min, which is among the highest values recorded in mammals; the heart rate increases exponentially with time from 100 to 800–1200 beats/min, and the respiratory rate rises linearly from 50 to 600–800 breaths/min.<ref name=j1>Template:Cite journal</ref>
Etruscan shrews mate primarily from March to October, though they can be pregnant at any time of the year. Pairs usually form in the spring and may tolerate each other and their young for some time at the nest. The gestation period is 27–28 days, and they have 2–6 cubs per litter.<ref name=iucn/><ref name= Macdonald/> Cubs are born naked and blind, weighing only Template:Convert. After their eyes open at 14 to 16 days old, they mature quickly. The mother usually moves the young when they are 9 to 10 days old, and if disturbed, she relocates them by leading them with her tail in a train-like formation, a behaviour known as caravanning,<ref>Template:Cite journal</ref> with each cub biting the tail of the one in front. The young Etruscan shrews are weaned at 20 days old. By three to four weeks of age, the young are independent and are soon sexually mature.<ref name=r1/><ref name= Macdonald/><ref name=m/>
DistributionEdit
The Etruscan shrew inhabits a belt extending between 10° and 40°N latitude across Eurasia.<ref name=j2/> In Southern Europe, it has been found in Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, France, North Macedonia, Malta, Montenegro, Greece, Italy, Portugal, Slovenia, Spain, and Turkey, with unconfirmed reports in Andorra, Gibraltar and Monaco; it has been introduced by humans to some European islands, such as Canary Islands.<ref name=iucn/>
The shrew also occurs in North Africa (Algeria, Egypt, Libya, Morocco, Tunisia) and around the Arabian Peninsula (Bahrain, Israel, Jordan, Lebanon, Oman, Syria, and Yemen including Socotra). In Asia, it was observed in Afghanistan, Azerbaijan, Bhutan, China (Gengma County only), Burma, Georgia, India, Iran, Iraq, Kazakhstan, Laos, Malaysia (Malaysian part of Borneo island), Nepal, Pakistan, Philippines, Sri Lanka, Tajikistan, Thailand, Turkey, Turkmenistan and Vietnam. There are unconfirmed reports of the Etruscan shrew in West and East Africa (Guinea, Nigeria, Ethiopia) and in Armenia, Brunei, Indonesia, Kuwait and Uzbekistan.<ref name=msw3/><ref name=r1>Suncus etruscus, Red Book of Kazakhstan (in Russian)</ref>
Overall the species is widespread and not threatened, but its density is generally lower than of the other shrews living in the area.<ref name=iucn/> In some regions it is rare, especially in Azerbaijan, Georgia, Jordan and Kazakhstan (included into the Red Book).<ref name=r1/>
HabitatEdit
The Etruscan shrew favors warm and damp habitats covered with shrubs, which it uses to hide from predators. Areas where open terrain such as grasslands and scrub meet deciduous forests are usually inhabited.<ref name= Macdonald/> It can be found at sea level but is usually confined to the foothills and lower belts of mountain ranges, though has been found up to Template:Convert above sea level.<ref name= Macdonald/> It colonizes riparian thickets along the banks of lakes and rivers, as well as human-cultivated areas (abandoned gardens, orchards, vineyards, olive groves and edges of fields). The shrew, however, avoids intensively cultivated areas, as well as dense forests and sand dunes.<ref name=iucn /> It is poorly adapted to digging burrows, so it arranges its nests in various natural shelters, crevices and others' uninhabited burrows.<ref name=r1/><ref name=r2/> They frequent rocks, boulders, stone walls and ruins, darting quickly in and out between them.<ref name= Macdonald/>
Hunting and feedingEdit
Because of its high ratio of surface area to body volume, the Etruscan shrew has an extremely fast metabolism and must eat 1.5–2.0 times its body weight in food per day. It feeds mostly on various invertebrates, including insects, larvae and earthworms, as well as the young of amphibians, lizards and rodents, and can hunt prey of nearly the same body size as itself. It prefers species with a soft, thin exoskeleton, so it avoids ants when given a choice. Grasshoppers, where common, are often regular prey.<ref name= Macdonald/> It kills large prey by a bite to the head and eats it immediately, but takes small insects back to its nest.<ref name=r1/><ref name=r2/><ref name=sc/> When hunting, it relies mostly on its sense of touch rather than vision, and may even run into its food at night.<ref name=m/>
Predators and threatsEdit
The largest threat to Etruscan shrews originates from human activities, particularly destruction of their nesting grounds and habitats as a result of farming. Etruscan shrews are also sensitive to weather changes, such as cold winters and dry periods.<ref name=r1/> Major predators are birds of prey.<ref name=r2/><ref name=m/>