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1

Why are shrews so small? The costs and benefits of small size in Northern temperate Sorex species in the context of foraging habits and prey supply

100%

Churchfield S.

Acta Theriologica. Supplement

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2002

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tom 47

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nr 1

This paper reviews the ecological advantages and disadvantages of very small body size in Sorex Linnaeus, 1758 shrews living at high latitudes with cold winters. It examines the feeding and foraging habits of small and large shrews in the context of prey supply, location of winter prey sources, territory requirements, habitat exploitation and inter-specific competition. Data on feeding habits and prey availability show that the major costs of small size are a reduction in food niche breadth and prey biomass resulting from restrictions on the type and size of prey eaten, and large territory requirements. Major benefits of small size are the ability to subsist on small, numerous and accessible arthropods with high encounter rates, enabling coexistence with larger congeners and exploitation of low-productivity habitats less suitable for larger earthworm-eating species. Small size, coupled with low per capita food intake, is shown to be of special adaptive value in cold winters when food supply is restricted mostly to small arthropods, and earthworms are few.

2

First results on the feeding ecology of sympatric shrews (Insectivora: Soricidae) in the Tai National Park, Ivory Coast

51%

Churchfield S., Barriere P., Hutterer R., Colyn M.

Acta Theriologica

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2004

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tom 49

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nr 1

The feeding ecology of a multi-species community of shrews inhabiting secondary forest and cacao-coffee plantations in the Tai National Park (Ivory Coast) was investigated. A total of 553 shrews were captured and 194 alimentary tracts were examined. Ten species were found, including Sylvisorex megalura and nine species of Crocidura, forming a series with respect to body size. New ecological data on these little known African species are presented. All species of shrews ate a wide diversity of arthropods, with Coleoptera, Araneae, Formicidae and Diplopoda making the largest dietary contributions. Lumbricidae were eaten by two species. C. obscurior had an exceptionally long intestine for its size but there was no evidence of dietary specialisation in this or other shrew species. All species investigated ate predominantly small prey and there was no correlation between size of prey items consumed and body mass of shrew species. There was little evidence of resource partitioning amongst the shrews, despite differences in body size.

3

Population dynamics and survivorship patterns in the common shrew Sorex araneus in southern England

51%

Churchfield S., Hollier J., Brown V. K.

Acta Theriologica

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1995

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tom 40

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nr 1

Results of a four-year, mark-recapture study of a high-density population of Sorex araneus Linnaeus, 1758 inhabiting grassland are reported. The population showed regular cycles of abundance between seasons and differences between years. Captures were not related to ambient temperature or rainfall, and population numbers showed no consistent correlation with winter weather conditions. Immigration and dispersal occurred throughout the year but were lowest in winter. Fifty-five percent of males and 35% of females in the breeding population were immigrants. Shrews underwent an autumn-winter weight loss of 12-19% but there was no evidence that weather conditions affected seasonal or annual patterns of weight change. There were no significant differences in body mass between resident and transient (and dispersing) young or between resident and immigrant adults. Weather conditions affected neither monthly survival, nor annual winter mortality rate which was 21-48%. Onset of sexual maturity was not affected by time of birth, but early-born cohorts had better survival rates at all stages than did late-born cohorts. There were significant differences in survival between cohorts born in different years but these were not correlated with weather conditions or population density.

Ograniczanie wyników

2 Acta Theriologica

1 Acta Theriologica. Supplement

3 Churchfield S.

1 Barriere P.

1 Brown V. K.

1 Colyn M.

1 Hollier J.

1 Hutterer R.

1 2004

1 2002

1 1995

Why are shrews so small? The costs and benefits of small size in Northern temperate Sorex species in the context of foraging habits and prey supply

First results on the feeding ecology of sympatric shrews (Insectivora: Soricidae) in the Tai National Park, Ivory Coast

Population dynamics and survivorship patterns in the common shrew Sorex araneus in southern England