Myosorex varius
{{Short description|Species of mammal}}
{{speciesbox
| image = Myosorex varius.png
| image_caption = Drawing of M. varius
| status = LC
| status_system = IUCN3.1
| genus = Myosorex
| species = varius
| authority = (Smuts, 1832)
| synonyms =
| range_map = Forest Shrew area.png
| range_map_caption = Forest shrew range
}}
The forest shrew (Myosorex varius) is a species of shrew in the mouse shrew family, Soricidae.{{MSW3 Soricomorpha| id = 13700323 | page = 266}} It is found in Lesotho, South Africa, and Eswatini.{{Cite iucn|url=https://www.iucnredlist.org/species/41382/115519477|title=The IUCN Red List of Threatened Species|access-date=2018-10-28}} Its natural habitats include temperate forests, dry savanna, Mediterranean-type shrubby vegetation, and temperate grassland. The term "forest shrews" in the plural is sometimes confusingly used to collectively refer to a different genus, Sylvisorex.
Description
The forest shrew grows to a length around {{convert|12.5|cm|0|abbr=on}} with a tail of {{convert|4.3|cm|1|abbr=on}} and an average mass of about {{convert|12|g|1|abbr=on}}. In KwaZulu-Natal and the Drakensberg region, the males are larger than the females, but in the Cape Colony, the sexes are of similar sizes. This shrew is covered in short, dense fur, dark grey or brown above and paler underneath.{{cite web |url=http://animaldiversity.ummz.umich.edu/accounts/Myosorex_varius/ |title=Myosorex varius: forest shrew |author=Joseph, Jency |year=2011 |work=Animal Diversity Web |access-date=23 February 2014}}
Distribution and habitat
Biology
The forest shrew excavates a shallow burrow or takes over the burrow of another small mammal. The complex of passages has several entrances and a nesting chamber containing dry grasses. These shrews are territorial and a breeding pair of shrews is often found in a nest.
The forest shrew is mainly nocturnal and is an insectivore, but its diet also includes any small invertebrates it can find, including earthworms, millipedes, centipedes, crustaceans, and spiders. The forest shrew is preyed upon by barn owls, marsh mongooses, striped weasels, and striped polecats. To avoid predation, it spends most of its time in its burrow and only leaves when it needs to feed or defecate. Its droppings are very pungent.
The breeding season varies across the forest shrew's range. In some areas, breeding takes place all year round, but in others, it is correlated with the higher rainfall which occurs in the summer, while unusually wet weather at other times of year can spark further reproductive activity.{{cite book |title=Advances in the Biology of Shrews II: Variation in aspects of the population dynamics of the endemic forest shrew Myosorex varius in South Africa |last1=Merritt |first1=Joseph F. (ed.)|last2=Baxter |first2=Rod M. |year=2005 |publisher=Lulu.com |isbn=9781411678187 |pages=179–187 |url=https://books.google.com/books?id=MrKLeOYjtV4C&q=Myosorex+varius&pg=PA179 }}
The forest shrew often contains the brachylaimid trematode Renylaima capensis in its kidney and ureter. This parasitic fluke has been found to have a three-host lifecycle, the first intermediate host being the terrestrial slug Ariostralis nebulosa and the second, another slug Ariopelta capensis. The forest shrew feeds on both these slugs.Sirgel, W. F.; Artigas, P.; Bargues, M. D.; Mas-Coma, S. (2012). "Life Cycle of Renylaima capensis, a Brachylaimid Trematode of Shrews and Slugs in South Africa: Two-host and Three-host Transmission Modalities Suggested by Epizootiology and DNA Sequencing". Parasites & Vectors 5: 169. {{doi|10.1186/1756-3305-5-169}}.
Feeding as it does on small invertebrates, the forest shrew tends to accumulate any environmental contaminants in its tissues. Earthworms are known to bioaccumulate lead and the levels of lead in forest shrews are found to rise when they eat contaminated earthworms. This enables the shrews to be used as bioindicators of heavy metal pollution.{{cite journal |author1=Reinecke, A. J. |author2=Reinecke, S. A. |author3=Musilbono, D. E. |author4=Chapman, A. |year=2000 |title=The Transfer of Lead (Pb) from Earthworms to Shrews (Myosorex varius) |journal=Archives of Environmental Contamination and Toxicology |volume=39 |issue=3 |pages=392–397 |doi=10.1007/s002440010120 |pmid=10948291 |s2cid=31190285 }}
Status
The IUCN lists the forest shrew as being of "Least Concern" because it has a wide distribution and is common over much of its range and the population seems stable. It is able to adapt to variations in its habitat and no specific threats have been identified.
References
{{Reflist}}
External links
{{Commons category|Myosorex varius}}
{{Soricomorpha|M.}}
{{Taxonbar|from=Q1768511}}