![]() ![]() ![]() It appears that a substantial part of the effect traditionally attributed to forest fragment size may be related to distance to the forest edge. The effect of forest fragment size was consistently accompanied with the effect of distance to the forest edge with the exception of only two generalist species. While frequency of the generalist species generally peaked somewhere close to the forest edge, frequency of sensitive forest resident species increased up to a distance of 150 m or more from the forest edge. The maximum frequency of species dependent on distance to the forest edge differed considerably along the line connecting forest edge to the centre of forest fragments. Spatial distribution of the majority of common forest bird species was significantly affected by distance to the forest edge and/or fragment size and vegetation. For this purpose we used generalized additive models (GAMs) with spline components and demonstrated the distance – frequency relationship for each bird species for whom it was relevant. Based on data from a four year bird survey, we explored the spatial distribution of 29 common forest bird species within 24 forest fragments (0.1–255 ha) in relation to distance to the forest edge, fragment size and forest vegetation. In this study, we attempted to determine whether and how forest bird species distribution was related to distance from the forest edge or clearing (whichever was closer) taking into consideration effects of fragment size and vegetation. However, the role of distance to the forest edge on the spatial distribution of bird communities within forest fragments remains largely unknown. Species-rich communities of forest birds generally occupy larger rather than smaller forest fragments. We conclude that there is little evidence from this or other studies of avian communities to support an edge effect of increased density and species richness, and no evidence of entirely ecotonal species. Thus, no species could be categorized as entirely ecotonal. Although 11 species were ecotone conspicuous, they also occurred in either heath or wood or both. Fourteen species were ecotone neutral but were habitat specialists on either the wood (13 spp.) or the heath (1 sp.). Three of these were habitat-generalist-ecotone-neutral. Of a total of 86 species, 31 occurred in sufficient numbers to categorize according to their habitat association (generalist, or heath or wood specialist) and their density at the ecotone (ecotone neutral, ecotone shy, or ecotone conspicuous). The outstanding pattern was that bird density and species richness in the wood habitat were twice as high as in the heath habitat. ANOVA showed a modest increase in bird density at the wood side of the ecotone, which may be partly due to sampling biases rather than to some inherent habitat value in the ecotone. Multivariate analysis showed that the bird community in the ecotone was intermediate between the heath and wood communities, indicating that the ecotone contained a mixing of species rather than a unique bird community. We studied the patterns of bird densities across heath-wood edges at replicated sites in three locations in southeastern Australia. Ecotones have been considered as unique environments, and the concepts of edge effect and ecotonal species have been widely used, especially in avian community ecology. ![]()
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