Research Objectives:

1. Quantify the habitat characteristics at the nest, territory, and area scales to determine which variables affect black-capped vireo nest success and fledgling survival.
   
   
2. Quantify adult behavior during different nest stages to determine if adult behavior affects black-capped vireo nest success and fledgling survival.
   
   
3. Determine which predators depredate black-capped vireo nests using nest cameras.
   
   
4. Determine if management practices on private land affect black-capped vireo success differently than management practices on public land.

Management Implications:

1. Identifying habitat variables that affect black-capped vireo nest success and fledgling survival at multiple scales will provide valuable information for land managers.
   
   
2. Habitat characteristics and the presence of nest predators may affect adult behavior which may in turn affect black-capped vireo nest success and fledgling survival.
   
   
3. Because most of the black-capped vireo’s range is in private ownership, recovery of this endangered songbird may depend on management practices on private land.

Project Summary:

Black-capped vireos (Vireo atricapilla) are federally endangered songbirds whose breeding range in the United States has been reduced to parts of Oklahoma and central and southwest Texas by habitat loss and degradation. Habitat characteristics can be highly variable across the range, with different species associations depending on location and past management activities, such as brush clearing and prescribed fire. Suitable habitat for black-capped vireos has been characterized as a patchy distribution of low, scrubby growth consisting of mostly deciduous woody shrubs and trees of irregular height; however, not much is known about which habitat types provide the best resources for vireos to successfully reproduce.

I am studying the effects of habitat characteristics and adult behavior on black-capped vireo nest success and fledgling survival at Kerr Wildlife Management Area (WMA, Texas Parks and Wildlife Department) and adjacent private lands in Kerr County. At Kerr WMA area, there are 3 black-capped vireo habitat types: shrubland, which consists of oak and other deciduous patches surrounded by a matrix of grassland; deciduous woodland; and oak-juniper woodland. I am investigating whether nest success and fledgling survival are different in deciduous and oak-juniper woodland than in what is considered typical (i.e., shrubland) suitable habitat.

As the vireos arrive, I locate territories by spot-mapping singing males.  I also attempt to capture adults using mist-nets to have uniquely marked individuals within the population. Within each territory, I locate and monitor black-capped vireo nests until the fate can be determined. Once nests are located, I randomly select some for video monitoring using small, continuously recording infrared cameras to be able to determine the primary nest predators. I also randomly select nests for behavioral observations (e.g. time spent incubating, nestling feeding rates).  When nestlings are 6-8 days old, I give each one a unique color band combination as well, to be able to determine post-fledging survival. Once the nest is no longer active, I take vegetation measurements including nest height, nest substrate species, substrate height, and percent concealment at the nest to examine which factors affect nest success.

Habitat characteristics can have an effect on nest success and fledgling survival.  Certain habitat characteristics may provide the cover necessary to conceal the nest from predators and brood parasites.  Therefore, black-capped vireo territories that are in the best quality habitat (i.e. habitat that provides conditions appropriate for individual or population persistence) should have higher nest success and fledgling survival than those in poorer quality habitat.  Managers can use this information for making management recommendations on private and public lands with the goal of conserving and eventually recovering this endangered songbird.