The Edge Effect and Ecotonal Species: Bird Communities Across a Natural Edge in Southeastern Australia

Abstract

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. We studied the patterns of bird densities across heath-wood edges at replicated sites in three locations in southeastern Australia. 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. 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. The outstanding pattern was that bird density and species richness in the wood habitat were twice as high as in the heath habitat. 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). Three of these were habitat-generalist-ecotone-neutral. Fourteen species were ecotone neutral but were habitat specialists on either the wood (13 spp.) or the heath (1 sp.). Three species were ecotone shy. Although 11 species were ecotone conspicuous, they also occurred in either heath or wood or both. Thus, no species could be categorized as entirely ecotonal. 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.

Bird functional diversity enhances insectivory at forest edges: a transcontinental experiment

“…The predominantly neutral or delayed responses of birds to forest edges reported in previous studies indicate a high variability of edge effects according to the biogeographic or regional landscape contexts (Baker et al, 2002;Laurance et al, 2007). Here, we found additional effects of landscape diversity on bird functional diversity, but not on avian insectivory, which was only significantly affected by edge effects.…”

“…For each of the 24 forest stands, we paired an edge and an interior plot located at 50 m from the edge (N = 24 9 2 = 48 plots). This distance was chosen according to previous studies that had demonstrated that 50 m was a recurrent threshold of approximate edge influence for forest vegetation and birds (Baker et al, 2002;Harper et al, 2005;Rodewald & Vitz, 2005). The use of 50 m distance allowed us to include small forest fragments in the experiment as well as larger stands to study a complete gradient of forest fragment size.…”

Response of Avian Communities in Large‐river Floodplains to Environmental Variation at Multiple Scales

“…Proximity to edge habitats has been found to play a key role in structuring bird communities (e.g., Flaspohler et al 2001, Baker et al 2002. Distance-to-edge and variables reflecting edge density did enter into some of our analyses, but explained relatively small amounts of variation.…”

Bird functional diversity decreases with time since disturbance: does patchy prescribed fire enhance ecosystem function?

“…Immediately after fire, structural and floristic differences between burnt and unburnt patches are pronounced, and are likely to decrease with TSF as burnt vegetation regenerates. Although edge effects can be negative for forest passerines (Baker et al 2002, Barbaro et al 2012, it is plausible that a complex configuration of burnt and unburnt patches enhances functional diversity because the edge zone provides unique resources (Law and Dickman 1998).…”