common shrew

Common shrews are found throughout the woodlands, grasslands, and hedgelands of Britain, Scandinavia, and Eastern Europe. Each shrew establishes a home range of 370 to 630 m² (440 to 750 yd²). Males often extend the boundaries during the breeding season to find females. Shrews are extremely territorial and will aggressively defend their home ranges from other shrews. They make their nests underground or under dense vegetation.

File:05-Common Shrew Spring Summer 2021 nX.webm

The common shrew's carnivorous and insectivorous diet consists of insects, slugs, spiders, worms, amphibians and small rodents. Shrews need to consume 200% to 300% of their body weight in food each day in order to survive; to achieve this they must eat every 2 to 3 hours, and they will starve if they go without food much longer than that. They do not hibernate because their bodies are too small to store sufficient fat reserves and they have a short fasting duration.{{Cite journal|last1=Churchfield|first1=Sara|last2=Rychlik|first2=Leszek|last3=Taylor|first3=Jan R. E.|date=2012-10-01|title=Food resources and foraging habits of the common shrew, Sorex araneus: does winter food shortage explain Dehnel's phenomenon? |journal=Oikos|language=en|volume=121|issue=10|pages=1593–1602|doi=10.1111/j.1600-0706.2011.20462.x|bibcode=2012Oikos.121.1593C |issn=1600-0706}}

Common shrews have evolved adaptations to survive through the winter. Their skulls shrink by nearly 20% and their brains get smaller by as much as 30%. Their other organs also lose mass and their spines get shorter. As a result, total body mass drops by about 18%. When spring returns, they grow until they reach roughly their original size. Scientists believe that low temperatures trigger their bodies to break down bones and tissues and absorb them. As temperatures start to rise with the onset of spring, their bodies start to rebuild the lost bones and tissues. This ability to shrink their bodies significantly reduces their food requirements and increases their chances of survival in the winter.{{Cite news|url=https://www.scientificamerican.com/article/small-minded-strategy-the-common-shrew-shrinks-its-head-to-survive-winter|title=Small-Minded Strategy: The Common Shrew Shrinks Its Head to Survive Winter|last=Stetka|first=Bret|work=Scientific American|access-date=2017-10-24|language=en}}{{Cite journal|last1=Lázaro|first1=Javier|last2=Dechmann|first2=Dina K.N.|last3=LaPoint|first3=Scott|last4=Wikelski|first4=Martin|last5=Hertel|first5=Moritz|date=2017-10-23|title=Profound reversible seasonal changes of individual skull size in a mammal|journal=Current Biology|language=en|volume=27|issue=20|pages=R1106–R1107|doi=10.1016/j.cub.2017.08.055|pmid=29065289|issn=0960-9822|doi-access=free|bibcode=2017CBio...27R1106L }} Common shrews exhibit three distinct seasonal phenotypes; however, these phenotypes have the same relative oxygen consumption despite varying temperatures.{{cite journal |last1=Schaeffer |first1=Paul |last2=O’Mara |first2=M. Teague |last3=Breiholz |first3=Japhet |last4=Keicher |first4=Lara |last5=Lázaro |first5=Javier |last6=Muturi |first6=Marion |last7=Dechmann |first7=Dina |title=Metabolic rate in common shrews is unaffected by temperature, leading to lower energetic costs through seasonal size reduction |journal=Royal Society Open Science |date=31 March 2020 |volume=7 |issue=4 |page=191989 | pmid=32431881| doi=10.1098/rsos.191989|pmc=7211839 |doi-access=free |bibcode=2020RSOS....791989S }}

Shrews have poor eyesight and instead use their excellent senses of smell and hearing to find food.

The common shrew breeding season lasts from April to September, but peaks during the summer months. After a gestation period of 24 to 25 days, a female gives birth to a litter of five to seven babies. A female rears two to four litters each year. The young are weaned and independent within 22 to 25 days.{{cite web |title= BBC Science and Nature: Animals |url= http://www.bbc.co.uk/nature/wildfacts/factfiles/260.shtml|access-date=11 September 2009}}

Young shrews often form a caravan behind their mother, each carrying the tail of its sibling in front with its mouth.

The chromosome number (karyotype) of Sorex araneus varies widely, with a number of distinct "chromosomal races" being present over the species' range. One such race was described in 2002 as a new species, S. antinorii. This is an example of chromosomal polymorphism (chromosomal variability as a result of chromosome fusions or disassociations).Polymorphism: when two or more clearly different phenotypes exist in the same interbreeding population of a species. Ford E.B. 1975. Ecological genetics, 4th ed.White M.J.D. 1973. The chromosomes. Chapman & Hall, London. p169

These karyotypes have been known to naturally hybridize, such as in the Petchora race and the Naryan-Mar variant in Northeastern Russia.{{cite journal |last1=Pavlova |first1=Svetlana |last2=Shchipanov |first2=Nikolay |title=New karyotypes of the common shrew Sorex araneus (Lipotyphla, Mammalia) at the northern periphery of the species range in European Russia |journal=Mammal Research |date=July 2019 |volume=64 |issue=3 |pages=455–459 |doi=10.1007/s13364-018-0409-6 |s2cid=53567760 |url=https://www.researchgate.net/publication/329021072}}

A study by Nanjing Normal University in 2019 found that Sorex araneus is capable of echolocation via high-frequency tittering and close-range spatial orientation. Comparison of genes involved in hearing between bats, bottlenose dolphins and Sorex araneus suggests that this is a result of convergent evolution.{{cite journal |last1=Chai |first1=Simin |last2=Tian |first2=Ran |last3=Rong |first3=Xinghua |last4=Li |first4=Guiting |last5=Chen |first5=Bingyao |last6=Ren |first6=Wenhua |last7=Xu |first7=Shixia |last8=Yang |first8=Guang |title=Evidence of Echolocation in the Common Shrew from Molecular Convergence with Other Echolocating Mammals |journal=Zoological Studies |date=25 February 2020 |volume=59 |issue=4 |doi=10.6620/ZS.2020.59-04 |url=http://zoolstud.sinica.edu.tw/Journals/59/59-04.pdf |access-date=4 May 2020 |archive-date=15 April 2022 |archive-url=https://web.archive.org/web/20220415172837/http://zoolstud.sinica.edu.tw/Journals/59/59-04.pdf |url-status=dead }}

File:Sorex minutus and Sorex araneus size comparison - en.jpgs (genus Sorex), size comparison]]

The common shrew is not an endangered species, but in Great Britain it, like other shrews, is protected from certain methods of killing by the Wildlife and Countryside Act of 1981.Wildlife and Countryside Act 1981 S11, [http://www.statutelaw.gov.uk/content.aspx?LegType=All+Legislation&title=wildlife+and+countryside+act&Year=1981&searchEnacted=0&extentMatchOnly=0&confersPower=0&blanketAmendment=0&sortAlpha=0&TYPE=QS&PageNumber=1&NavFrom=0&parentActiveTextDocId=809266&ActiveTextDocId=809398&filesize=2877 Sch 6]

In Britain, shrews can be found at densities of up to one per 200 m² (240 yd²) in woodlands. The main predators of shrews are owls, cats, weasels, snakes, stoats, and red foxes.{{cite book |title= British Wildlife|year= 2002|publisher= Collins|location= London|isbn= 0-00-713716-8|page= 402}}

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{{Commons}}

{{Wikispecies|Sorex araneus}}

• [https://web.archive.org/web/20050404192127/http://www.arkive.org/species/ARK/mammals/Sorex_araneus/ ARKive on the common shrew]
• [https://www.bbc.co.uk/nature/life/Common_Shrew BBC information on the common shrew]
• View the [https://web.archive.org/web/20131216075317/http://www.ensembl.org/Sorex_araneus/Info/Index shrew genome] in Ensembl
• {{UCSC genomes|sorAra2}}

{{Eulipotyphla|S2.}}

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Category:Sorex

Category:Animals that use echolocation

Category:Mammals of Europe

Category:Mammals of Russia

Category:Mammals of Turkey

Category:Mammals described in 1758

Category:Taxa named by Carl Linnaeus