Effect of habitat fragmentation on distribution, density and breeding performance of the middle spotted woodpecker Dendrocopos medius (Alves, Picidae) in Nerussa-Desna Polesye [Russian]

摘要

The effect of habitat fragmentation on the state of middle spotted woodpecker population in the Nerussa-Desna Polesye (52 degrees 18'-52 degrees 50'N, 33 degrees 28'-34 degrees 40'E) was studied in 1997 and 1998. The distribution, density and breeding performance of the population were compared in continuous and fragmented habitats (oak forests). Thirteen and fourteen pairs were distributed over a study plot of 95.6 ha in the continuous habitat. Thirty fragments of habitat (plots of 3.3 to 19.1 ha, total area is 248.9 ha) were investigated. In 1997 and 1998, the woodpecker was registered in 5 and 8 plots, respectively; territorial pairs inhabited only 4 and 5 plots, respectively. The density of the population in the continuous oak forest fragmented habitats was 1.36-1.46 and 0.16-0.20 territorial pairs/10 ha, respectively. All the reproduction indices were higher in the continuous habitat than in fragmented ones. Nonetheless, the only parameter (proportion of eggs fledged) was statistically significant: 82.8 (n = 93 eggs) and 61% (n = 41 eggs) in continuous and fragmented habitats, respectively (p < 0.01). The results obtained suggest an adverse effect of habitat fragmentation on the middle spotted woodpecker population.