Management for oak regeneration: Short‐term effects on the bird community and suitability of shelterwood harvests for canopy songbirds

Abstract

AbstractInterest in regenerating oaks (Quercus spp.) has promoted use of partial harvesting techniques that create an open forest structure. From 2007 to 2009, we studied songbirds in mixed‐oak forests in southeastern Ohio, comparing shelterwoods recently harvested to 50% stocking and closed‐canopy mature second‐growth. We surveyed birds using distance‐based methods (56 line transects in 18 stands at 4 forests). We intensively investigated suitability of shelterwoods for canopy‐nesting species by examining habitat preferences, as measured by settlement patterns, age distributions, and site fidelity; we also examined nesting success. Several midstory and ground‐nesting species were 26–73% less abundant in shelterwood than unharvested stands, whereas shrub‐nesting species increased >100% several years post‐harvesting. Canopy‐nesting species were 31–98% more abundant in shelterwoods, but cerulean warbler (Setophaga cerulea) responses varied by forest. Patterns of settlement and site fidelity were generally similar among stands. Proportions of young males were actually greater for several species in shelterwood than unharvested stands, which may have been a consequence of young birds colonizing newly created (or improved) habitat. Even in our predominantly forested study system, nesting success (>700 nests) was low, ranging from 15% to 19% for yellow‐throated vireos (Vireo flavifrons) and cerulean warblers, to 27–36% for scarlet tanagers, blue‐gray gnatcatchers (Polioptila caerulea) and eastern wood‐pewees (Contopus virens). However, nest survival did not differ between shelterwood and unharvested stands, possibly because numbers of avian predators did not change with harvesting. Despite increased numbers of brown‐headed cowbirds (Molothrus ater) in shelterwoods, only 2% of canopy nests in which young could be identified were parasitized. Although these results suggest shelterwood harvests containing abundant overstory trees can provide short‐term breeding habitat for canopy songbirds, long‐term responses of birds to partial harvesting may differ from those documented here depending on different management options employed. Management for oak regeneration will typically remove all overstory trees later in the cutting cycle, initially resulting in loss of nesting substrates and hence breeding habitat for canopy songbirds. © 2011 The Wildlife Society.