We are exploring the relationships between Loggerhead Shrikes (occupancy, health, subspecies composition, and age structure) and agricultural practices and features in the Mississippi Alluvial Valley. The Loggerhead Shrike, known also as the ‘Butcher Bird’ for its habit of impaling its prey (e.g., mice, frogs, snakes, and insects) on thorns (or barbed wire), is a predatory songbird that is considered a Species of Greatest Conservation Concern across much of its range because of severe population declines over the past 50 years (-3%/yr). The population of the eastern migratory subspecies (L. l. migrans) has declined at an even more precipitous rate (-3.7%/yr) than the year-round resident subspecies (L. l. ludovicianus). Furthermore, a third, unnamed migratory subspecies (L. l. ssp.) that breeds in Canada, is considered Critically Endangered with only 55 individuals remaining. The cause of the Loggerhead Shrike’s decline is broadly attributed to habitat degradation and/or habitat loss, but it is unclear what specific factors are responsible for these declines or if various subspecies are affected by different factors. Based on sparse citizen science data (e.g., ebird and Breeding Bird Survey), agricultural landscapes in appear to be important for both resident and migratory shrikes, but little rigorous scientific information exists regarding this relationship. For instance, we know little about what proportion of birds that spend the winter in different regions (or other areas in the mid-south) are migratory. We also know little about habitat preferences or movements during the non-breeding season. Shrikes, in general, use open habitat characterized by grasses and forbs interspersed with bare ground, shrubs, and small trees year-round. In much of the Lower Mississippi Alluvial Valley, this now consists mainly of margins of row crop fields. However, it is currently unknown which habitat types, and what finer-scale features (e.g., row crop type, ditches, field margins, or isolated trees), are most preferred, how these different habitat types/features impact shrike survival during the winter, or how this may vary by age, sex, and/or subspecies. Of particular interest to agriculture is how different human activities and agricultural practices (e.g., crop types, pesticides, agricultural buffers) may affect the species (or subspecies).
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