Breeding range (km2 x 106)

Figure 13.9 (a, b) Sizes of breeding and wintering ranges of 57 landbird species which breed entirely in Eurasia and winter entirely in Africa. (c) Relationship between sizes of breeding and wintering ranges of the same 57 species. Warblers are shown separately as open circles. From Newton (1995a).

larger than the wintering range. This is significantly greater than the expected 50% (x2 = 4.0, P < 0.05). The most extreme example is the Lesser Grey Shrike Lanius minor, whose breeding range in Eurasia covers an area at least seven times greater than its known wintering range in southwest Africa, which is centred on the Kalahari basin (Herremans 1998). In contrast, in only 31% of species is the wintering range larger than the breeding range. The most extreme examples include the Olive-tree Warbler Hippolais olivetorum and Subalpine Warbler Sylvia cantillans, whose known wintering ranges cover more than twice the area of their respective breeding ranges. However, these low-density species are little known in Africa, and their effective wintering ranges may have been overestimated by the inclusion of records of vagrants or of occurrences in occasional years only.

0 0

Post a comment