Effects of patch size, isolation and regional abundance on forest bird communities

Abstract

The aim of this study was to assess the impact of isolation on forest bird communities in agricultural landscapes in The Netherlands. We studied the avifauna of 235 small (0.1-39 ha) woodlots composed of mature deciduous trees in [1984][1985]. These woodlots were selected in the eastern and central/southern part of the country within 22 regions showing great differences in landscape structure, i.e., degree of isolation. Multiple regression analysis indicated that woodlot size was the best single predictor of species number and probability of occurrence of most species. It turned out that the isolation variables, area of wood, number of woods, interpatch distance, and proximity and density of connecting elements, explained small but significant parts of the residual variances in species number. No single species was significantly affected by the density of connecting elements. Biogeographical differences between two groups of regions were emphasized. Evidence of four woodland species suggested that regional abundance affected the probability of occurrence in small isolates.

Influences of forest type and habitat structure on bird assemblages of oak (Quercus spp.) and pine (Pinus spp.) stands in southwestern Turkey

“…Stand size and connectivity to surrounding forest stands are known to be important determinants of forest bird assemblages in both native forests and plantations (e.g. van Dorp and Opdam, 1987;Enoksson et al, 1995;Díaz et al, 1998), implying that smaller isolated patches of forests may have a lower species richness than larger patches of the same habitat. In a Spanish study, Santos et al, (2002) found that native stands of holm oak (Q. ilex) had to be of significantly larger size than similar stands located in central Europe in order to support equal numbers of bird territories and species.…”

Effects of habitat cover, landscape structure and spatial variables on the abundance of birds in an agricultural–forest mosaic

“…However, it is equally important to avoid placing too strong an emphasis on just one or a few explanatory factors while neglecting others (Van Dorp & Opdam 1987;Borcard, Legendre & Drapeau 1992). Our results suggest that when exploring avian abundance patterns and their relationships to landscape structure, it is important to study simultaneously the effects of ecologically more proximate explanatory variables.…”

“…Modelling approaches have an important role in birdenvironment studies in different environments, such as agricultural landscapes, forests and wetlands, because they provide assessments of the key factors maintaining avian diversity and spatial predictions for conservation planning (Van Dorp & Opdam 1987;Ormerod & Watkinson 2000;Opdam & Wiens 2002;Suárez-Seoane, Osborne & Alonso 2002;Rushton, Ormerod & Kerby 2004). A variety of ecological issues, including bird species distribution ( Robinson, Wilson & Crick 2001), abundance patterns of different bird groups (Chamberlain et al .…”

Integrated effects of urban morphology on birdsong loudness and visibility of green areas

“…Patch sizes in idealised open spaces vary from 0.28 to 2.25 ha, and the patch sizes in the actual urban morphology are 0.1 to 2.02 ha, except for one patch with an area of 0.06 ha. The effects of patch size on avian density and nesting are debated; it has been suggested that they are not clearly influenced by patch size but vary among regions, number of years of vegetation and species (Winter et al, 2006;Davis, 2004;Schmiegelow and Mönkkönen, 2002;Schieck et al, 1995;Andrén, 1994;Van Dorp and Opdam, 1987). However, van Dorp and Opdam (1987) utilised 0.1 ha as a lower limit for the habitat of birds and proved that multiple bird species inhabited patches of 0.1 ha.…”