Non-breeding Ecology of Loggerhead Shrikes in Kentucky

Abstract

Populations of Loggerhead Shrikes (Lanius ludovicianus) across North America have been declining, and factors responsible for this decline remain unclear. Few studies have focused on the availability and use of wintering habitat. Our objectives were to ascertain the size and characteristics of Loggerhead Shrike territories, and examine the hunting behavior of shrikes during the non-breeding season. We observed 1,372 hunting attempts by 19 shrikes; arthropods (65.3%) and other invertebrates (23.3%) were the most common prey. Characteristics of habitat at used and randomly selected, apparently unused isolated and continuous perch sites differed (P = 0.023 and P = 0.021, respectively). Used perches had less grass cover, more bare ground, and denser, shorter vegetation. We found no difference between characteristics of occupied and unoccupied areas (P = 0.34). Non-breeding territories in our study were larger (mean = 85 ha) than those reported for shrikes during the breeding season. The availability of suitable winter habitat does not appear to be limiting Loggerhead Shrike populations in Kentucky. However, most Loggerhead Shrikes winter south of Kentucky where densities are higher, and it is possible that availability of suitable habitat might be a limiting factor in some areas.