Habitat selection and habitat‐specific survival of fledgling ovenbirds (Seiurus aurocapilla)

Abstract

Patterns of habitat use by some passerines change after the young leave the nest, and thus our understanding of habitat selection derived from counts of singing males earlier in the nesting cycle may not adequately represent the breeding habitat requirements of these species. Post-fledging changes in habitat use may have important conservation implications if the survival of fledglings is affected by characteristics of the habitat; however, there have been relatively few systematic studies of the post-fledging ecology of forest passerines and, of these, even fewer have incorporated analyses of the relationship between habitat characteristics and fledgling survival. We studied the post-fledging habitat selection and survival of ovenbirds Seiurus aurocapilla in northern New Hampshire, USA during two breeding seasons using radio telemetry. Habitat at sites used by radio-marked fledgling ovenbirds was characterized by fewer large trees and greater vertical structure 0-3 m above ground than ovenbird nest sites. Similarly, habitat at sites used by fledgling ovenbirds was characterized by fewer large trees and greater vertical structure than unused sites. Most (80%) of the 15 mortalities that we observed were due to predation. Nine (70%) of these occurred within the first 3 days of fledging, resulting in a significant drop in survival during this period. Fledgling survival increased significantly with increased vegetation structure. Our observations that fledgling ovenbirds are selective in their habitat use, that they select different habitat features than adult ovenbirds select for nesting and that fledgling survival is positively associated with these habitat features suggest that the use of habitat models based on counts of singing males before fledging does not adequately represent the habitat needs of this species. Conceivably, mortality during the postfledging period could limit recruitment to levels insufficient to maintain the viability of ovenbird population even if adequate nesting habitat were available.

Experimental effects of early‐life corticosterone on the hypothalamic–pituitary–adrenal axis and pre‐migratory behaviour in a wild songbird

“…Dixon 1972;Anders et al 1997;Cohen & Lindell 2004;King et al 2006;Rivers et al 2012), I did not find evidence that corticosterone-treated birds had higher survival rates during the pre-migratory period compared to sham or controls. One explanation may be the lack of power due to the low number of recaptures.…”

Recent advances in understanding migration systems of New World land birds

“…Juvenile Swainson's Thrush (Catharus ustulatus) move from riparian areas to mixed-hardwood forests and coastal scrub after fledging, searching for ripening fruit (White et al 2005). Recent netting studies within clearcuts in eastern deciduous forest have expanded the list of forest-breeding species that appear to use second-growth vegetation in late summer, but these studies did not show if such habitats were required by these species (Marshall et al 2003, King et al 2006, Vitz and Rodewald 2006; J. Faaborg, P. A. Porneluzi, R. Brito-Aguilar, and R. L. Clawson, unpublished manuscript). These post-breeding habitats may be critical to both the juvenile and adult survival components of breeding-season fitness, but they have not been studied in depth (Ahlering andFaaborg 2006, Whittaker andMarzluff 2009).…”

Effects of clearcutting, patch cutting, and low-density shelterwoods on breeding birds and tree regeneration in New Hampshire northern hardwoods

“…Common explanations given for high bird use in young regenerating stands during these two critical time periods are increased areas of cover and/or high insect and fruit abundance associated with these areas (Anders et al 1998, King et al 2006, McDermott and Wood 2010, Rodewald and Brittingham 2004, Vitz and Rodewald 2007. Additionally, Stoleson (2010) found that capture rates increased almost linearly with increasing clearcut size, suggesting that larger cuts may provide a greater benefit.…”