Status and Management of the Black-capped Vireo at Fort Sill, Oklahoma, 1988-91

Abstract : Environmental regulations require Army installation land management personnel to protect endangered species on Army land. The black-capped vireo (Vireo atricapillus), which is on the Federal list of endangered species, occurs on the Fort Sill Military Reservation, OK, and also on military installations in Texas. Major threats to the species include nest parasitism by brown-headed cowbirds (Molothrus ater) and habitat loss. The U.S. Army Construction Engineering Research Laboratories (USACERL) evaluated the distribution, abundance, dispersal, minimum survival, habitat requirements, and reproductive success of vireos on Fort Sill. A search of suitable habitat on the entire installation was conducted in 1988, and the locations, numbers, and reproductive success of the vireos were determined. This study concludes that conditions at Fort Sill are favorable for the continued presence of vireos, and that the major threat to the vireo on Fort Sill and throughout its range is cowbird nest parasitism. The study recommends cowbird control measures to enhance vireo reproductive success, and continued annual monitoring and data collection on black-capped vireo numbers, age classes, and reproduction. Specific data-collection procedures are outlined. Options for other potential long-term research, monitoring, and management considerations are also provided. Black-capped vireo, Fort Sill, OK. Cowbird parasitism, Endangered species,