GTNP Breeding Bird Monitoring Project: The 2006 Season Year-to-Year Variation in Avian Breeding Densities in Grand Teton National Park.

Abstract

Census work was carried out in mid­ June on 10 of the 30 breeding bird monitoring sites formally established in the mid 1990s. The censuses conducted in 2006 spanned a range of habitats from grassland and sage through willows and cottonwoods to pine and spruce-fir forest. Collectively, the sites cover all habitats within Grand Teton National Park, from lowest to highest elevations, and have produced records of 158 bird species since project initiation. Dry conditions prevailed in GTNP in late winter 2006 and extended into the spring and summer. Similarly, dry conditions were widespread in the overwintering areas of many of the migrants breeding within the park, from southern and southwestern USA south into northern and western Mexico. The 2006 breeding birds showed overall lower densities, with especially low numbers in those species typical of wetland habitats. On the other hand, many species characteristic of drier habitats within the park and with geographic ranges extending south and west of the park were more common than usual. Comparisons are drawn, for different suites of birds, between 2006 densities and the long term average densities at the monitoring sites. Some attempt is made to distinguish between on-site and off-site influences on breeding bird densities, although these efforts remain tentative.