ASSESSING THE DISTRIBUTION OF WINTERING RUSTY BLACKBIRD POPULATIONS USING CITIZEN SCIENTIST GENERATED DATA
Once common, Rusty Blackbirds (RUBL) populations have experienced one of the steepest known declines of any North American bird (declining by 90% since 1960). Habitat loss, predominantly of forested wetlands, in RUBL’s wintering range has been implicated as a key contributor to the decline, however our ability to assess the effects of this or other contributing factors is limited by uncertainties in the distribution of RUBL populations during the nonbreeding season. To address this, eBird and the RUBL Working Group established the Winter Hotspots Blitz, a citizen science project in which participants reported RUBL observations between Jan. and Feb. of 2009-2011. Using these data, in conjunction with 15 bioclimatic variables thought to predict RUBL habitat, we developed habitat suitability models to assess how RUBL distributions might vary by flock size and within environmental space. Average monthly precipitation and minimum temperatures were most predictive of RUBL presence across flock size classes (< 20, 20-99, and > 100 individuals). The proportional landscape composition of floodplain forests was positively associated with RUBL presence, as was row crop, pasture, and mixed forest habitat. Shrub, hardwood, and upland forests were negatively associated with RUBL presence. Flock size classes were found to occupy different portions of environmental niche space, with a differential response to floodplain forest (increasing importance with flock size) being the primary contributor. Likewise, predicted suitable habitat area within our study region decreased with increasing flock size. This project will aid our understanding of how RUBL populations are distributed and help us isolate areas in which research and conservation efforts might be most effective.
Evans, B. S., University of North Carolina, Smithsonian Migratory Bird Center, USA, firstname.lastname@example.org
Powell, L. L., Smithsonian Migratory Bird Center, USA, email@example.com
Location: Longs Peak - Diamond East
Presentation is given by student: Yes