Canopy characteristics affect reproductive success of golden‐cheeked warblers

Abstract

The golden‐cheeked warbler (Setophaga chrysoparia), listed by the U.S. Fish and Wildlife Service as endangered in 1990 due primarily to habitat loss and fragmentation, is a Neotropical migrant songbird that breeds exclusively in mature juniper–oak (Juniperus–Quercus) woodlands in central Texas, USA. Previous studies suggested suitable breeding habitat consists of >35% canopy closure (with 50–70% cover optimal), and ≥10% oak composition. However, little is known about this species' habitat relationships at the southwestern edge of its breeding range. Therefore, within this portion of the species' breeding range, we investigated influences of canopy closure and tree species composition on pairing and reproductive success of golden‐cheeked warblers during 2009 and 2010. We used remote sensing and ground sampling to acquire variables to describe habitat characteristics, and we estimated pairing for breeding and reproductive success by golden‐cheeked warblers. We found successfully breeding pairs in areas with >20% canopy cover, 35% juniper composition, and only 3% oak composition. A logistic model for pairing success retained juniper, oak, and the interaction between these 2 variables, and the model for reproductive success retained juniper, canopy closure, study area, and the interaction between canopy closure and study area. Our results expand our knowledge of habitat conditions that warblers use for breeding, thus expanding the range of habitat management options available for this species during breeding season. © 2012 The Wildlife Society.

Using LiDAR‐derived vegetation metrics for high‐resolution, species distribution models for conservation planning

“…Thus, our results provide some new insight into understanding how to describe where vireos occur and may help guide future investigations into why vireos occur where they do. For both species, recent research has suggested that previously assumed habitat relationships may in fact vary across the species' ranges, among years, among individuals, and in the context of various social and behavioral conditions (Pope 2011, Klassen et al 2012, Smith et al 2012. The capacity to estimate vegetation height and perhaps other structural metrics remotely to relate to species response variables among years, across regions, and even among territories or nest sites can provide an essential tool for developing a more complete and accurate understanding of the habitat associations for these species and provide insight into the mechanisms driving these patterns.…”

“…We erred on the side of being inclusive in the sampling frame, not a priori restricting sampling to areas generally considered habitat for either species (Wilkins et al 2005, Groce et al 2010) because recent research indicates habitat use may differ from previous assumptions (Pope 2011, Klassen et al 2012, Smith et al 2012). We generated a 300 3 300 m grid of sample points initiated at a random starting point (n ¼ 1341; Thompson 2002).…”

“…Using recent work on both species (Collier et al 2010, Pope 2011, Collier et al 2012, Klassen et al 2012, McFarland et al 2012a, Smith et al 2012, we developed candidate models: (1) models including only LiDAR-derived vegetative metrics (W L ), (2) composite models incorporating LiDAR-derived vegetation metrics and non-LiDAR-derived environmental metrics (W LC ), and (3) models including only non-LiDAR-derived vegetation and environmental metrics (W N ) (Appendix A: Table A1, Appendix B: Table B1) to determine whether models that included LiDAR-derived metrics were more competitive than those without LiDAR-derived metrics. To create a resource selection surface prediction, we generated a 100-m-radius hexagonal grid over the prediction area from a random starting point.…”

Survival of Red-headed Woodpeckers' (Melanerpes erythrocephalus) nests in northern New York

“…Habitat Variables.-Habitat features associated with nest-site selection can affect avian nest survival by influencing predation rates, nest defense, microclimates, and food abundance for provisioning young (e.g., Newlon and Saab 2011, Klassen et al 2012, Kozma and Kroll 2012. We sampled habitat characteristics related to the nest cavity, nest tree, and surrounding vegetation that were thought to influence survival of Red-headed Woodpeckers' nests.…”

Age-specific survival of male Golden-cheeked Warblers on the Fort Hood Military Reservation, Texas

“…Thus, a new PVA is warranted and might significantly alter our outlook on GCWA viability. In recent years much effort has been expended to update our knowledge on GCWA abundance and reproduction both at the local and range-wide scale (e.g., abundance, Hunt et al 2012, Collier et al 2013, Peak and Thompson 2013, Warren et al 2013reproduction, Campomizzi et al 2012, Klassen et al 2012, Marshall et al 2013. Apparent survival (Φ) has been estimated for juvenile (hatch year, HY) and adult (after hatch year, AHY) male GCWAs while accounting for imperfect detection in the past, where Φ is the probability that an individual remains alive and returns to the study area from one sampling occasion to the next.…”