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1

Species richness relative abundances and habitat use in local assemblages of Sorex shrews in Eurasian boreal forests

100%

Sheftel B. I. , Hanski I.

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nr 1

EN

Using a large body of observational data on the occurrence of Sorex shrews in boreal forests, we test two models that predict the structure of small mammal communities along a gradient of increasing habitat productivity. Tilman's (1982) model predicts a humped curve of species richness along productivity gradients. In contrast, we found a linear increase in species richness with increasing logarithm of the pooled density of shrews, which we use as a measure of habitat productivity for shrews. The model of Hanski and Kaikusalo (1989) assumes a trade-off between exploitative and interference competitive abilities, and it predicts that the size structure of small mammal communities should shift from the dominance of small species (superior in exploitative competition) in unproductive habitats to the dominance of large species (superior in interference competition) in productive habitats. Shrew assemblages show such a shift. Though it is not possible to draw definite conclusions about the role of interspecific competition from our observational data, the changing size structure of local shrew assemblages with increasing habitat productivity is a predictable feature of their community structure.

2

Home ranges of sympatric soricine shrews in Hokkaido, Japan

100%

Ohdachi S.

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1992

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tom 37

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nr 1-2

EN

Home ranges of sympatric shrews, Sorex unguiculatus Dobson, 1890 S. gracillimus Thomas, 1907 and S. caecutiens Thomas, 1907 were studied by a mark-recepture method during the non-snow covered seasons in northern Hokkaido, 1988 and 1989. Home range size of S. unguiculatus, the largest species (15.1 g for adult males), was not significantly different from that of S. gracillimus, the smallest species (4.4 g for adult males). Both S. unguiculatus and S. gracillimus had more exclusive home ranges within species than between species. Tolerance of home range overlap may be related to the reduction of dietary overlap. No reliable information of home range for S. caecutiens was obtained in this study.

3

Aging and cohort dynamics in Sorex shrews

84%

Gliwicz J. , Jancewicz E.

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nr 3

EN

In the shrews Sorex araneus Linnaeus, 1758 and S. minutus Linnaeus, 1766 a short period of fast post-natal development in the nest is followed by a longer summer period of developmental stasis and then by autumn regression. The aim of this paper has been to test whether this period of developmental stability also is accompanied by inhibited development of the eye lens - the most continuously growing organ of the mammalian body. If it is not, then can this be used as an age indicator in studies on shrews, and can it serve in distinguishing seasonal cohorts of young born in consecutive summer months? This aspect was examined on material comprising dead shrews collected from live traps and pitfalls set for rodent research in the marshy habitat of a river valley in Białowieża Forest, Poland, in 1997-1999. In fact, the eye lens in shrews was shown to increase in size continuously; therefore it may be used as a reliable age indicator. Body mass of weaned young shrews also continued to increase slowly with age until autumn. On the basis of the distribution of individuals in successive lens-mass classes, three age groups (cohorts) of young could be distinguished each season in the S. araneus population, and two in S. minutus. In the former species, consistent patterns to the relative abundance of the three seasonal cohorts were observed. The consequences of time of birth on individual fitness in Sorex shrews are discussed.

4

Overlap of temporal niches among four sympatric species of shrews

67%

Rychlik L.

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tom 50

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nr 2

EN

Hypotheses about the dependence of circadian activity from metabolic rate and the segregation of temporal niches among competing species were verified by the study of activity patterns in a shrew community of two semiaquatic species,Neomys anomalus Cabrera, 1907 andN. fodiens (Pennant, 1771), and two terrestrial species,Sorex araneus Linnaeus, 1758 andS. minutus Linnaeus, 1766, co-existing in wet habitats of Białowieża Forest (E Poland). In ten trapping sessions, performed in early summer between 1991 and 2000, traps were open 24 hours continuously and patrolled at 1:00, 5:00, 10:00, 15:00, and 20:00. All the shrew species were most active between 20:00 and 1:00, and least active around mid-day (10:00–15:00). However, activity of the twoSorex species was lower than that of the twoNeomys species in the period 20:00–1:00, but higher in the period 15:00–20:00. BothNeomys species displayed clearly nocturnal, unimodal patterns of activity. In contrast, activity of bothSorex species was relatively evenly distributed over 24 hours and they increased their activity earlier (ie after 15:00) than bothNeomys species (after 20:00). These results confirm the idea that small shrew species with higher metabolic rate have more frequent and more equally distributed activity bouts than large species. Overlap of temporal niches was the highest within genera (99.29% between bothNeomys species and 98.36% between bothSorex species), the lowest betweenN. fodiens andS. araneus (88.26%) andS. minutus (89.34%), and intermediate betweenN. anomalus and bothSorex species (91.78 and 93.34%, respectively). Such high interspecific overlaps in activity suggest a joint-action of other mechanisms that separate ecological niches of these species also in other dimensions (eg food, microhabitat).

5

Cestodes of shrews [Insectivora, Soricidae] from the Magadan region, North-East Siberia

67%

Novikov M. V.

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nr 1

EN

Five species of Sorex shrews (S. caecutiens, S. isodon, S. daphaenodon, S. gracillimus and S. minutissimus) were studied for helminths in North-East Asia. 11 cestode species were described. For 5 of them S. isodon and S. gracillimus were recorded as new hosts. Geographical distribution and community structure of found cestodes are briefly analyzed. A role of different shrew species in the helminth circulation is also discussed.

6

Fossil remains of shrews (Soricomorpha: Soricidae) and desmans (Talpidae: Desmaninae) from Norfolk, England, with biostratigraphic implications for the Plio-Pleistocene boundary in East Anglia

59%

Harrison D. L. , Parfitt S.A. S. A.

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tom 52A

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nr 1-2