BREEDING BIRDS AT THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY, 1985-1991

During the summers of 1985-1991, bird censuses were conducted along 13 permanent routes located at the 2315-km(2) Idaho National Engineering and Environmental Laboratory (INEEL, formerly INEL) in southeastern I daho. The objectives of the surveys were to (1) compare avifauna in an d near facility complex sites with remote, relatively undisturbed habi tats, (2) identify trends in populations of sagebrush-obligate species and other common shrubsteppe species, and (3) determine the presence, abundance, and population status of species of special concern. Five routes were official U.S. Geological Survey, Biological Resources Divi sion 40.0-km Breeding Bird Survey (BBS) routes (formerly administered by the U.S. Fish and Wildlife Service) located in relatively remote po rtions of the INEEL where access by humans was controlled and limited. Eight shorter routes (5.8-19.2 lan in length) were near INEEL facilit y complexes, which more regularly experienced disturbance by humans. T he surveys recorded 25,597 individuals representing 90 species. Wester n Meadowlarks (Sturnella neglecta), Brewer's Sparrows (Spizella brewer i), Sage Sparrows (Amphispiza belli), Horned Larks (Eremophila alpestr is), and Sage Thrashers (Oreascoptes montanus) comprised 72% of all in dividuals. Almost half of all species were represented by fewer than 1 0 individuals. Bird density was significantly greater along facility c omplex routes. Moreover because of human-constructed wetlands and stru ctures of various types, facility complex routes had significantly mor e bird species per unit area, including more species of waterfowl and human-associated species. Some year-to-year variation in bird density was related to weather. More individuals were recorded in cooler, wett er years, although such increases were reflected more along facility c omplex routes. Among sagebrush-obligate species, trend analysis sugges ts that both Brewer's Sparrows and Sage Sparrows increased significant ly in abundance, which may be in contrast to regional trends for these species. Of 5 species of special concern observed trend analysis coul d be performed for only 2: Ferruginous Hawks (Buteo regalis) and Logge rhead Shrikes (Lanius ludovicianus). Both species had more routes with negative regression coefficients and negative trend means, indicating that declines may have occurred although the goodness-of-fit test for neither species was significant. These data from the INEEL should be useful for comparison with future studies at the site and other studie s from throughout the Great Basin region.