Riparian Bird-Habitat Association Models: A Framework for Informing Management and Developing Restoration Guidelines in Utah

Approximately 75% of the avian species in Utah use riparian habitats at some time during their life cycles and at least 80% of this habitat in Utah has been lost or altered since settlement; currently 0.6% of land cover in Utah is considered riparian. In 1992, with the support of Utah Partner's in Flight, the Utah Division of Wildlife Resources began a statewide neotropical migratory bird (NTMB) and habitat monitoring program to assess the status of bird populations at 31 sites. Additional sites (up to 52) were added in later years; bird and habitat assessments at 37 riparian sites have been continuously monitored since 1998. Using this long-term dataset, my primary study goals were to: 1) estimate abundance and densities of 38 focal avian species, 2) document and describe changes in riparian vegetation over time, and 3) investigate how these two processes are related by creating bird-habitat association models. Recent results from population trend analyses suggest that the patterns of annual variation and regional synchrony seen in riparian-dependent species groupings may be driven by landscape-wide effects on habitat. I developed riparian-bird habitat association models to better understand these large-scale effects using important variables specific to nine species of interest. I constructed classification and regression trees for three distinct foraging guilds to assess species-specific and community level habitat associations. Variables identified as important predictors of species density varied according to the species of interset. However, the variables selected by the classification models were consistent with each species life history strategies. Model results are intended to provide the framework for the development of management guidelines that will inform terrestrial riparian restoration and conservation efforts in Utah.