BIRD COMMUNITIES AS INDICATORS OF RIPARIAN HABITAT QUALITY IN THE ROARING FORK WATERSHED, SOUTHERN ROCKY MOUNTAINS, COLORADO Delia G. Malone and John C. Emerick Introduction Riparian areas are critical components of stream ecosystems (Ward 1989). Riparian vegetation type, quality, cover and extent contribute to instream physical habitat and influence water quantity and quality. Disturbances or alteration to riparian vegetation may also alter riparian habitat structure and functions, which can lead to aquatic habitat degradation. Habitat alterations and environmental stressors are often reflected in changes in the community of riparian and aquatic fauna. Thus wildlife community composition can potentially be used to develop an Index of Biotic Integrity (IBI) which can then be used to characterize the ecological conditions of a particular habitat. Birds are ideal for use as an IBI because they are highly mobile and thus their presence or absence can be a reflection of the relative quality or suitability of the available habitat. Many neotropical migrant songbirds are sensitive to disturbance (Terborgh 1989; Wilcove and Terborgh 1984) and may thus be good indicators of ecosystem integrity (Hutto and Young 2002).However, because disturbance occurs throughout their migratory range, an Index of Biological Integrity for birds, should be developed for a particular region, and should be based on current assessment of the quality of available habitat, and should not be limited to the presence or absence of particular species. In this study we examine the following hypotheses: ˆü Riparian avian community composition will vary corresponding to changes in riparian habitat quality ˆü Bird species sensitivity to disturbance and tolerance may vary between geographic regions and thus an effective IBI should be developed that is specific to a given region. ˆü Variation in breeding bird community composition will enable the development of a Bird Index of Biotic Integrity specific to the Roaring Fork Watershed. Methods We located 62 sampling transects in riparian habitat in three life zones, Upper Sonoran, Lower Montane and Upper Montane. We selected sites along a human disturbance gradient from minimally disturbed to highly disturbed, urbanized habitats. At each site, we established a linear transect along which five points were located 100 meters apart. At each point we conducted breeding bird point count surveys and characterized the riparian habitat with regard to four parameters: 1) vegetation structure and species composition; 2) habitat quality with regard to riparian function; 3) habitat integrity (percent intact native habitat); and 4) impact intensity. We ranked Impact Intensity during surveys at each sites along a disturbance gradient and identified the assemblage of breeding birds at each site. Disturbance tolerant and intolerant bird species were distinguished from ubiquitous species and generalists by the use of literature review (DeGraff et al 2009, BLM 2009, Beason et al. 2005 and others) and field experience (Malone and Emerick 2003, Malone and Emerick 2007). Statistical Analysis Multiple correlation analysis was used to explore relationships between habitat variables and metrics related to the avian community. Birds in the avian community of each reach were classified into guilds, including feeding guilds (e.g. insectivores, omnivores, granivores), nesting guilds (e.g. tree nesters, shrub nesters, ground nesters), and other groups (e.g. neotropical migrants, warblers, riparian dependent birds, birds that were tolerant of disturbance, and birds intolerant of disturbance). We were particularly interested in correlations with the three metrics related to the quality of the riparian habitat, Habitat Quality, Habitat Integrity, and Impact Intensity. Some of the results of the multiple correlation analysis are shown in Table 1. There is a consistent correlation between Habitat Quality, Habitat Integrity, and Impact Intensity across all life zones, even though the means of estimating each of these variables are different. Also noted is a recurring positive correlation between total vegetation cover, disturbance intolerant birds, and Habitat Quality and Integrity, and a recurring negative correlation between these variables and Impact Intensity. Results from the Upper Sonoran reaches are more similar to results from the Montane reaches as compared to Lower Montane reach results, with respect to the nature and number of significant correlations. This suggests that an increase in the number of Lower Montane reaches to be censused in 2009 might reveal other significant correlations, possibly more in line with the results from the other two life zones. It must be mentioned that this analysis is preliminary, and although we recognize that some of the reaches appear to be outliers in the analysis, we have no plans to remove them from the 2009 census. Results Bird species community diversity ranged widely between sites and throughout the watershed. Altogether we recorded 118 species in 62 reaches with abundances that varied from 20 to 167 individuals and species richness from 6 to 37 per site. Diversity, as calculated by the Shannon Weaver diversity index varied from 1.67 to 3.37 where the higher number indicates greater diversity. These results are roughly similar to earlier results connected with the initial stream and riparian assessment conducted from 2004 through 2006 (Malone and Emerick 2007) In summary, results of the statistical analysis show some strong correlations between avian community characteristics and habitat quality metrics, and appear to indicate that an increase in the number of Lower Montane reaches to be censused in 2009 is warranted. Plans for the 2009 Field Season During the 2009 breeding season we will conduct a second round of breeding bird censuses. We will also add eight sites in Lower Montane ecosystems for a total of 70 sites. A habitat assessment will be conducted at each of the eight new sites. After data collection we will conduct a more comprehensive statistical analysis so that we can estimate an avian IBI. We may consider conducting a third year of censusing depending on results from these two years and the strength of the bird IBI. Table 1. Results of the Multiple Correlation Analysis. Shown are Pearson product moment correlation coefficients between variable pairs, grouped according to life zone. All correlations shown are significantly non-zero at the 95% confidence level. Negative values indicate inverse correlations, where one variable increased while the other decreased. Literature Cited Beason, J.R. Levad and T. Leukering. 2005. Monitoring Colorado’Äôs Birds: the 2004 field season report. Unpub. report, Rocky Mountain Bird Observatory, Brighton, CO. 80603 Bureau of Land Management. 2009. Birds as indicators of riparian vegetation condition in the western U.S. Bureau of Land Management, Partners in Flight, Boise, Idaho. BLM/ID/PT-98/004+6635. 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