Habitat use by Loggerhead Shrikes (Lanius ludovicianus) in the Lower Mississippi Alluvial Valley, USA

Loggerhead Shrikes (Lanius ludovicianus) are widely distributed across North America, but populations have declined precipitously across the range over the past 50 years. Shrikes occur in open habitats such as grasslands and shrubland, and hypotheses for their range-wide decline include habitat loss and degradation and changing agricultural practices. Understanding the winter ecology and population demography of shrikes has been identified as research priorities for conservation and management. To address these research needs, we conducted repeated point counts at 348 sites in eastern Arkansas (USA) between November 2016 and March 2017. At each site, we measured vegetation within 100 and 250m and used GIS to quantify land cover and crop data within 100, 250, 500 and 1,000m to characterize habitat use in winter. Land cover data include the percentage of land that is forest, grassland, developed, wetland, or cultivated crops. Site occupancy in winter was 23%, and repeated surveys and relocations of marked birds indicate that detectability is low or that shrikes readily move across the landscape. Preliminary analyses show no relationship between shrike habitat use and our land cover variables. Behavioral observations suggest that shrikes might depend heavily on rights-of-way (narrow strips of grassy habitat between roads and agricultural fields), and we will test whether habitat features, such as the width and height of grasses and presence of perches, along rights-of-way relate to the presence of shrikes. Future work includes continued surveys, nest monitoring, and banding and marking of shrikes to characterize their winter habitat use and demography.