| Publication Type: | Journal Article |
| Year of Publication: | 2011 |
| Authors: | Wesołowski, T |
| Journal: | Journal of Ornithology |
| Volume: | 152 |
| Issue: | 2 |
| Date Published: | 2011 |
| ISBN Number: | 2193-7192 |
| Keywords: | Europe, Poland, Sylvia, Sylvia atricapilla, Sylviidae |
| Abstract: | Data on Blackcaps Sylvia atricapilla gathered in 1975–2007 in an old-growth primeval forest (Białowieża National Park, Poland) are analysed to see whether the species numbers, breeding phenology or reproduction showed any long-term trends. Neither the clutch size (mean 4.8) nor the nesting success (c. 38%) changed, but a number of directional changes during 33 years were observed. In comparison with the 1970s, in the twenty-first century, Blackcaps arrived over 2 weeks earlier, but advanced egg-laying by only 8 days. The breeding numbers increased threefold; they had been increasing slowly before 2000, but almost exponentially from 2001 onwards. The densities raised to c. 10 pairs/10 ha in luxuriant riverine habitats. Due to structural changes in the oak-hornbeam habitat, in the twenty-first century, Blackcaps situated nests lower and less frequently in conifers. The numerical increases were only partially accountable by structural changes in local habitats, but they were concordant with large-scale increases of Blackcaps across W Europe. It is hypothesised that the forest has recently been invaded by Blackcaps from strongly increasing, SW migrating, populations. |
| URL: | http://dx.doi.org/10.1007/s10336-010-0585-x |
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