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All mammal depredations occurred in riparian 
areas, which was likely because mammals used 
Dolan Creek and washes as corridors between 
vireo habitats to move through the study area. 
Riparian corridors are an important landscape 
element for predators and guide animal movement 
including foraging (Small and Hunter 1988. Noss 
1991, Marini et al. 1995. Barding and Nelson 
2008). Most of the vegetation outside the wash 
areas is thick and possibly difficult for mammals 
to move through relative to the washes. 
The main predator of Black-capped Vireo nests 
in 2009 was the Brown-headed Cowbird. It is 
possible that cowbird depredations cause hosts to 
re-nest and subsequently parasitize the new host 
nest attempt (Arcese et al. 1996). There were no 
cattle within the study area or on the surrounding 
properties during our study: however, there was a 
substantial population of feral sheep and aoudad 
that may have attracted Brown-headed Cowbirds. 
Cowbirds may also be attracted to the food supply 
created by supplemental deer (Odocoiletis spp.) 
feeding occurring on many of the adjacent 
properties; some deer feeders occur only a few 
meters from the DRSNA fence line (KNS, pers. 
obs.). Black-capped Vireo habitat at DRSNA 
occurs within the typical distance to deer feeders 
that cowbirds have been observed to commute 
between feeding and breeding areas (7-13 km; 
Thompson 1994. Curson et al. 2000), potentially 
facilitating depredation and parasitism of vireo 
nests within the study area. 
No vegetation management or predator or 
Brown-headed Cowbird control was conducted 
in the Devil’s River area during 2009-2010. 
Our study provides information on the impact 
and diversity of nest predators, as w'ell as the 
impact of parasitism and rainfall on the Black- 
capped Vireo population in the area. Thus, 
more concise efforts can be made to fulfill the 
goal ol conserving Black-capped Vireos in 
southwest Texas and all regions of their 
breeding range. 
ACKNOWLEDGMENTS 
We thank the Texas Parks and Wildlife Department and 
The Nature Conservancy for access to their properties for 
field work; M. P. Sheick. C. R. Thompson. A. M. Salinas. 
M. G. Hepp. and I. I . Johnson for assistance collecting 
field data; 1. 1.. Conkling for help with camera logistics; 
and R. T. Snelgrove, A. G. Snclgrovc, T. L. Pope II A 
Mathewson. T. M. McFarland, V, L. McCallister, I.. G. 
Law, and B. A. Collier for logistical and technical 
support. Research funding was provided hy Texas 
Department of Transportation and Texas Parks and 
Wildlife Department. Additional support was provided 
by the College of Arts and Sciences and Department of 
Biological and Environmental Science. Texas A&M 
University-Commerce. 
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