Winter mortality of northern bobwhites: Effects of food plots and weather

Knowledge of winter mortality is lacking for many avian populations, but its importance is widely recognized. We estimated winter mortality in a northern bobwhite (Colinus virginianus) population on the Fort Riley Military Reservation in northeastern Kansas by locating, flushing, and counting individual northern bob whites in coveys each month from December through March during 1961-1967 and 1968-1980. Number and duration of days of less than or equal to-5 degrees C and days with snow cover were obtained for each winter. Of the 403 coveys monitored, 198 had access to food plots (<600 m) and 205 did not (>900 m from food plots). December-to-March mortality of northern bobwhites near food plots ranged from 24% to 46% ((X) over bar = 34%), whereas mortality for those far from food plots was 20% to 82% ((X) over bar = 50%). Number of days with snow cover of greater than or equal to 10 cm and duration of less than or equal to-5 degrees C temperatures during January were significantly correlated with mortality and were the best predictors of winter mortality of northern bobwhites.