Introduction

1. Introduction Preliminary Results Objectives During the field season of 2011, 25 May – 22 June, we recovered geolocators from 14 RWBL and 1 YHBL, that were attached in 2010. The locator data were recovered and are currently being processed. In preliminary findings migratory routes of RWBL and YHBL appear to have species specific routes. RWBL that breed in eastern ND appear to migrate to spatially proximate winter roosts, suggesting that populations share both breeding and wintering sites. The single YHBL seemed to travel much further south and west into regions of Mexico during the winter months. Although graphically this may be evident, further research must be completed to directly correlate these findings with future data. Further study of temporal migration patterns are also needed to identify if the RWBL and YHBL are migrating earlier. Northern blackbird populations are migratory, wintering in the southern United States and Mexico and breeding in the northern United States and Canada. While roosts during the breeding season are generally small and dispersed throughout the landscape, winter roosts are exceedingly large, with millions of birds often concentrating at a single location. Several blackbird species have been studied extensively because their large population numbers frequently result in extensive damage to agriculture. Blackbirds are also an excellent species for modeling how global climate change may affect the migratory ecology of passerine birds. Such factors that may be impacted by global climate change include the seasonal timing of migration, routes used, and stopover habitats visited. Finally, we have little information about the fine-scale migratory patterns of small birds. By using real-time data gathered from light-level geolocators, we are documenting detailed migratory routes that will be plotted visually using Global Information Systems (GIS). Additionally, these data will provide detailed baseline information that can be used to track changes in bird migration patterns in relation to climate change, an objective outlined in the United States Department of Agriculture(USDA) Wildlife Services (WS) National Wildlife Research Center Blackbird Project Plan. Determine the migratory routes and winter roost sites of male Red-winged Blackbirds and Yellow-headed Blackbirds nesting in North Dakota. Develop landscape maps of habitat types in the area of migratory stop-over sites and winter roosts. Predict potential changes in stop-over sites, winter sites and breeding grounds due to climate change. Migratory Routes and Winter Roosts of Male Red-winged Blackbirds (Agelaiusphoeniceus) and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) Nesting in North DakotaDereck Stonefish1, George Linz2, William Bleier1, Jeffrey Homan2, and Erin Gillam11Department of Biological Sciences, NDSU, Fargo, ND 581082USDA, Wildlife Services, National Wildlife Research Center, Bismarck, ND 58501 Methods We have used a combination of light-level geolocator tags and classic banding methods to investigate the migratory patterns and winter roost locations of male Red-winged Blackbirds (RWBL) and Yellow-headed Blackbirds (YHBL) that breed in North Dakota. During the breeding season, we deployed geolocators on 48 blackbirds (35 RWBL and 13 YHBL) in 2010, and 52 blackbirds (17 RWBL and 35 YHBL) in 2011. Geolocators are a newly available technology in which a tag attached to a bird records sunrise and sunset times for up to a year. These data are then treated using a algorithm to provide spatial correction and processed into latitude and longitude coordinates. Geolocators have been used in previous research to track migratory pathways and locate wintering grounds of neotropical birds. Acknowledgements Funding is provided by NSF GRFP, ND EPSCoR, USDA Wildlife Services, National Wildlife Research Center and North Dakota State University Magnified to show Geolocator