Breeding Bird Survey Results 2009

Stoller-ESER-128


EXECUTIVE SUMMARY

Breeding bird surveys (BBSs) have been conducted annually since 1985 (no surveys were conducted in 1992 and 1993) to monitor bird populations on the Idaho National Laboratory (INL) Site. In 2009, we conducted surveys from June 3 to 30 along 13 established routes, five of which are part of a nationwide survey administered by the U.S. Geological Survey (USGS), and eight of which circumscribe INL Site facilities. We documented 5,072 birds from 55 species during these surveys. Bird abundance was greater than the 1985-2008 average of 5,018 birds, but the number of species observed (i.e., species richness) was lower than the 22-year average of 59.


Compared with past surveys, we observed similar patterns of bird abundance among those species that are typically most numerous. In 2009, the five species that were surveyed in greatest abundance were horned lark (Eremophila alpestris, n = 1,466), western meadowlark (Sturnella neglecta, n = 1,071), Brewer’s sparrow (Spizella breweri, n = 743), sage thrasher (Oreoscoptes montanus, n = 516), and sage sparrow (Amphispiza belli, n = 367). During 23 years of breeding bird surveys on the INL Site, these species have been the five most abundant 18 times, and in the remaining five years they were among the six most abundant species. Considering declines reported in populations of sagebrush-obligate species throughout the intermountain west, this trend indicates that the quality of sagebrush-steppe habitat on the INL Site remains stable.  
Although three new species were added in the past two years to the list of birds that have been observed at least once during BBSs on the INL Site, no new observations were made in 2009. Four species were observed, however, that had been recorded in ≤ 6 of the past 22 years. These include American goldfinch (Carduelis tristis), western tanager (Piranga ludoviciana), northern mockingbird (Mimus polyglottos), and northern pintail (Anas acuta).      

    
Species observed during the 2009 BBSs that are considered imperiled or critically imperiled in Idaho include the long-billed curlew (Numenius americanus, n = 2), Franklin’s gull (Larus pipixcan, n = 26), and grasshopper sparrow (Ammodramus savannarum, n = 4).


 

FUTURE DATA ANALYSIS


With over two decades of BBS data collected, we are well positioned to conduct a long-term analysis of bird population trends for species occupying the INL Site. Past reports have provided details regarding particular species, but no effort has been made to consider a comprehensive analysis of all BBS data from the INL Site. In the near future, we plan to analyze all data from past BBSs, and to investigate long-term trends in bird abundance and species richness. The results of such an analysis will be submitted to a peer-reviewed journal for publication and will be included in an annual report to the U.S. Department of Energy.


Landscape Change and Habitat Variation


The habitat and vegetation communities across the INL Site are a mosaic of sagebrush-steppe habitat. The INL Site has experienced some large, natural disturbances (e.g., wildfire) which have caused changes in vegetation community composition and distribution across the site. Little is known, however, concerning responses of bird populations to alterations of habitat composition and distribution across the landscape and how habitat fragmentation can influence local populations. Local bird populations and community assemblages can respond to these habitat changes, and the long-term BBS data should reflect these changes. We will investigate the patterns of habitat change in conjunction with changes in observed bird abundance and richness along routes.


Long-term Community Diversity Trend


Diversity indices have not been calculated each year, and a useful comparison would be to calculate Shannon’s H and EH for all BBS routes for all years to assess which routes have experienced significant change in bird community abundance. The initial community diversity results reported here consider community differences between different routes in the same year. It is unknown how diversity on the same route has changed over time. A number of community similarity indices, such as Morisita’s index, can be calculated to address this question. We anticipate coupling the results from the spatial analysis described above with the results from community diversity change over time to present a comprehensive description of how bird communities have changed on the INL Site since 1985.


Full 2009 Breeding Bird Survey Report (pdf format)