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

Abstract

b s t r a c tTimber harvesting has been proposed as a management tool to enhance breeding habitat for the Cerulean Warbler (Setophaga cerulea), a declining Neotropical-Nearctic migratory songbird that nests in the canopy of mature eastern deciduous forests. To evaluate how this single-species management focus might fit within an ecologically based management approach for multiple forest birds, we performed a manipulative experiment using four treatments (three intensities of timber harvests and an unharvested control) at each of seven study areas within the core Cerulean Warbler breeding range. We collected preharvest (one year) and post-harvest (four years) data on the territory density of Cerulean Warblers and six additional focal species, avian community relative abundance, and several key habitat variables. We evaluated the avian and habitat responses across the 3-32 m 2 ha À1 residual basal area (RBA) range of the treatments. Cerulean Warbler territory density peaked with medium RBA ($16 m 2 ha À1 ). In contrast, territory densities of the other focal species were negatively related to RBA (e.g., Hooded Warbler [Setophaga citrina]), were positively related to RBA (e.g., Ovenbird [Seiurus aurocapilla]), or were not sensitive to this measure (Scarlet Tanager [Piranga olivacea]). Some species (e.g., Hooded Warbler) increased with time post-treatment and were likely tied to a developing understory, whereas declines (e.g., Ovenbird) were immediate. Relative abundance responses of additional species were consistent with the territory density responses of the focal species. Across the RBA gradient, greatest separation in the avian community was between early successional forest species (e.g., Yellow-breasted Chat [Icteria virens]) and closed-canopy mature forest species (e.g., Ovenbird), with the Cerulean Warbler and other species located intermediate to these two extremes. Overall, our results suggest that harvests within 10-20 m 2 ha À1 RBA yield the largest increases in Cerulean Warblers, benefit additional disturbance-dependent species, and may retain closed-canopy species but at reduced levels. Harvests outside the optimum RBA range for Cerulean Warblers can support bird assemblages specifically associated with early or late (closed-canopy) successional stages.

Diurnal space use and nocturnal roost-site selection by male Cerulean Warblers during the breeding season

“…,b, Perkins and Wood , Sheehan et al. ). However, their habitat selection can vary, particularly in response to disturbance at the local scale (Boves et al.…”

Positive association between forest management, environmental change, and forest bird abundance

“…farmlands, in Europe (Donald et al 2001;Inger et al 2015;Reif and Hanzelka 2016;European Bird Census Council 2018), but confirm the observed population trends of woodland bird species in Europe (Gregory et al 2007;Ram et al 2017). In temperate regions with stable amounts of forested land cover and sustainable forest management, non-migratory forest bird populations are stable or even increasing, with evidence that both migratory and resident species may benefit from moderate-intensity forest management or disturbance (King and DeGraaf 2000;Bakermans and Rodewald 2009;Sheehan et al 2014). Our results suggest that the overall decline in bird abundance and diversity could be mitigated by focusing on non-forest ecosystems.…”

“…They found that they peaked in forests with intermediate levels of residual basal area, yet late successional species responded negatively to increasing forest management intensity. Compared to forests in NE-USA, or at least those studied in Sheehan et al (2014), European managed forests typically reach much higher basal areas and higher small-scale diversity in age classes and structure. Thus, late successional bird species in Europe likely had sufficient access to nesting and feeding sites to maintain their abundance levels.…”

Forest restoration to attract a putative umbrella species, the white‐backed woodpecker, benefited saproxylic beetles

“…It can be difficult to quantify restoration needs at the landscape level, but habitat requirements of umbrella species might provide a mechanism for determining tangible targets. In fact, recent findings suggest that umbrella species can guide management efforts (Branton and Richardson v www.esajournals.org 2014, Sheehan et al 2014).…”

“…In the USA, pinegrassland communities have been restored for the red-cockaded woodpecker (Picoides borealis) with positive outcomes for other bird species associated with fire-induced environments (Wilson et al 1995). Forest management for the cerulean warbler (Setophaga cerulean) has also been shown to benefit other disturbance-dependent bird species (Sheehan et al 2014). Crosstaxon studies are uncommon, and to our knowledge we are among the first to evaluate the effects of ecological restoration for an umbrella species from the perspective of another taxonomic group.…”