Wood Thrush Postfledging Movements and Habitat Use in Northern Virginia

Abstract

We monitored 42 radio-tagged, fledgling Wood Thrushes (Hylocichla mustelina) to investigate movement and habitat use during the postfledging period. Fledglings' mean (? SE) age at dispersal from the natal sites was 32.5 5 0.6 days post hatching. First dispersal sites were located 1.5 ? 0.3 km from the natal site. All young joined flocks of juveniles, except three birds that remained solitary. Sixteen birds stayed at the first dispersal site until departure on migration, whereas nine visited additional dispersal sites. On 40 occasions, 15 fledglings moved up to 6 km from their dispersal sites. Before late August, 96.7% of fledglings' locations occurred in: (1) second growth scrub/deciduous sapling sites located along forest borders and abandoned farms (59.4%), (2) gypsy moth (Lymantria dispar) damaged deciduous forest (24.4%) and (3) Virginia pine (Pinus virginianus) forest with heavy deciduous understory (12.8%). Fruiting trees and shrubs used as food sources by juveniles fruit earlier in these habitats. After late August, an increased number of fledgling locations (14.1%) occurred in mature deciduous or mixed forest, possibly tracking the later fruiting cycles of understory plants in these habitats. Twenty-four of 33 fledglings left the study area in September. Mean age at departure was 81 ? 5 days post hatching. We suggest that postfledging movements in Wood Thrushes are keyed by the availability of food resources and the presence of conspecifics, although other factors may play a role. We conclude that successful conservation of migratory species requires protection of habitats used during the postfledging period as well as those used during the nesting portion of the life cycle.

Effects of forest management on vertebrates: synthesizing two decades of data from hardwood forests in Missouri,USA

“…These findings are consistent with previous studies that reported higher Wood Thrush densities in 100-m buffer zones surrounding regeneration cuts, and in unharvested stands that were adjacent to recently harvested stands (Wallendorf et al 2007, Kendrick et al 2015. The Wood Thrush is typically classified as a mature forest species, but juveniles and adults make use of shrubland habitat and small canopy openings during the post-breeding period (Anders et al 1998, Rappole et al 1998, Porneluzi et al 2014). Thus, the increased diversity in forest age structure in evenaged compartments may have promoted Wood Thrush populations in the unharvested and/or thinned stands of the compartment, even as abundance declined inside the actual clearcut openings (Vitz and Rodewald 2006).…”

Natal dispersers pay a lifetime cost to increased reproductive effort in a wild bird population

“…compared with non-dispersers [17,44]. In migratory species, young can acquire knowledge about the natal area by remaining near their birth site before the onset of migration [45,46]. Natal dispersers may therefore lack such knowledge about their settlement area.…”

Response of Bicknell’s Thrush (Catharus bicknelli) to boreal silviculture and forest stand edges: a radio-tracking study

“…Several authors have reported similar behaviour, with both adult and juvenile Wood Thrushes (Hylocichla mustelina (J.F. Gmelin, 1789)) feeding, from the time of dispersal from the nest site until fall migration, on a variety of fruits that successively reach maturity during that period (Anders et al 1998;Vega Rivera et al 1998a, 1998b, 1999. Major (2010) observed an increased in fruit trees and shrub abundance <10 years after PCT, similar to what we observed (PCT-96 vs. PCT-86).…”