EVIDENCE FOR YEAR-ROUND RESIDENCY OF GRAY HAWKS FROM THE LOWER RIO GRANDE VALLEY TO WEBB COUNTY, TEXAS

Gray Hawks (Buteo plagiatus) are generally considered migratory in much of their United States range, but recent telemetry research has demonstrated year-round residency of breeding adults in the Lower Rio Grande Valley of Texas. Whether this pattern extends farther upriver along the Rio Grande has remained uncertain. We used GPS telemetry from two adult male Gray Hawks tracked in Webb County, Texas, to document annual space use and evaluate evidence for residency outside the Lower Rio Grande Valley. Both individuals remained spatially constrained within a consistent area throughout the annual cycle, and seasonal analyses indicated use of the same general areas during winter months, with no evidence of long-distance seasonal migration. Winter community-science observations (2010-2025) further corroborate repeated Gray Hawk presence in the region. Together, these findings extend telemetry-based evidence of year-round residency approximately 170 km northward along the Rio Grande corridor and suggest a broader zone of non-migratory behavior in south Texas.