Species-Specific Edge Effects on Nest Success and Breeding Bird Density in a Forested Landscape

Abstract

Using natural nests of eight bird species, we provide one of the first multispecies tests for edge effects on reproductive success in a forested landscape. Our primary objective was to assess whether distance to the edge of recent clearcuts was related to nesting success in intact northern hardwood forests. Estimated nest success was generally lower for the two ground‐nesting species than for the six canopy‐nesting species. Brood parasitism was <3% for species which typically accept eggs of the Brown‐headed Cowbird (Molothrus ater), and nest predation was the most common cause of nest failure. Probability of nest failure was influenced by distance to forest edge for the ground‐nesting Hermit Thrush (Catharus guttatus) and Ovenbird (Seiurus aurocapillus), but not for six canopy‐nesting species. For the Hermit Thrush and Ovenbird, nest success relative to decreasing distance to the edge was reduced during the nestling stage, but not the incubation stage. Nest density appeared to be higher in forest zones near the clearcut edge for ground‐nesting and for several canopy‐nesting species. Our data suggest that the effect of proximity to edge on nest success for ground‐nesting species may penetrate 300 m into intact forest, while the effect of proximity to edge on nest density may penetrate farther. These data suggest that the creation of openings in forested landscapes reduces nest success and increases nest density for some species of migratory birds in a zone adjacent to the opening. This pattern supports the notion that “ecological traps” may exist for ground‐nesting birds in areas near recently created forest openings. Because areas of contiguous forest (e.g., publicly owned forest) in the Upper Great Lakes remain relatively intact, they may serve as source habitat for regional songbird metapopulations.

Testing mechanistic explanations for mammalian predator responses to habitat edges

“…Our study did not quantify the habitatspecific distribution of alternative food resources that may supplement part of the carnivore diet, such as passerine birds, bird clutches, amphibians, insect, or fruit. Although these resources are usually a less important part of the diet of mammalian carnivores (Goszczyński 1986;Genovesi et al 1996;Martinoli et al 2001), most are also likely to be more abundant at forest edges compared to heavily exploited grasslands and forests (Buse and Good 1993;Flashpohler et al 2001;Lázaro et al 2005;Šálek et al 2009). Nevertheless, habitat quality for predators also includes other (complementary) sources than food.…”

Ohio's Forests 2011

“…Edge effects vary somewhat with distance from forest edge, depending on the type of edge and species of vegetation or wildlife, (e.g., Chen et al 1992, Rosenberg et al 1999, Flaspohler et al 2001, but 100 to 300 feet is frequently used as a general range for the 'vanishing distance' or the distance into a patch where the edge effect disappears and interior forest conditions begin.…”

Habitat fragmentation reduces nest survival in an Afrotropical bird community in a biodiversity hotspot

“…Habitat fragmentation results in a reduction in area, an increase in remnant isolation, the creation of edge, and an alteration in the habitat structure of the remnants, all of which may contribute either directly or indirectly to changes in avian nest survival (3)(4)(5)(6). Given that nearly two thirds of all bird species are endemic to the tropics (7,8) and that moist tropical forests are being lost worldwide at a rate of 0.52% annually (9), understanding the impact of habitat fragmentation on the demography of tropical birds is clearly important for avian conservation.…”