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

Abstract

Interest 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.

Foraging behavior of Cerulean Warblers during the breeding and non-breeding seasons: evidence for the breeding currency hypothesis

“…During the breeding season, we also observed Cerulean Warblers provisioning young at nests in Ohio from 2007 to 2009 (Newell and Rodewald , ). We conducted 30‐min observations of nestling provisioning behavior (51 nests in 39 territories), focusing on the later nestling phase when adults were actively feeding young (>80% of nestlings observed were at least 4 days old based on estimated hatching dates).…”

“…We observed foraging behavior from 27 April through 9 July at six sites in two state forests in Vinton and Jackson counties. Three sites had recently been partially harvested to ∼50% stocking (Newell and Rodewald , ). During the non‐breeding season, we studied Cerulean Warblers at six shade coffee farms on the western slopes of the Cordillera de Merida in the Venezuelan Andes (Bakermans et al , , Newell et al ).…”

Bird response to fire severity and repeated burning in upland hardwood forest

“…Other studies in hardwood forests also have found that densities of many species are not detectably changed following low-intensity prescribed burns (Aquilani et al, 2000;Artman et al, 2001) or other silvicultural treatments with a moderate to high level of canopy retention (Moorman and Guynn, 2001;Newell and Rodewald, 2012).…”

Avian response to timber harvesting applied experimentally to manage Cerulean Warbler breeding populations

“…Removing the residual canopy in stages, as is sometimes done, perhaps may extend the benefits for canopy-dependent birds. However, the benefits for these species will eventually end due to often complete overstory removal later in the cutting cycle (Newell and Rodewald, 2012). Further, as these stands age the understory will eventually become unsuitable for some gap-dependent species.…”

“…Management strategies specifically intended to benefit Cerulean Warblers may be implemented across large areas in their core breeding range, and thus may have a large effect on the overall bird community. While studies within the core range of Cerulean Warblers have examined effects of specific timber harvest prescriptions on bird communities (e.g., Newell and Rodewald, 2012), knowledge of the effects of Cerulean Warbler management on a full range of early to late successional forest bird species is lacking.…”