Non-Breeding Behavior and Diet of Loggerhead Shrikes in an Intensive Agricultural Region

Abstract

As agricultural conversion has transformed the landscape across the central United States, populations of grassland-associated species, such as those of Lanius ludovicianus (Loggerhead Shrike), have declined. Understanding the ecology and behavior of grassland species in these highly anthropogenic, agricultural landscapes provides vital information for conservation efforts. However, few studies have assessed the ecology and behavior of this species in intensive agricultural areas, especially during the potentially critical nonbreeding season. To help fill these knowledge gaps, we used direct behavioral and larder surveys to describe the non-breeding ecology and behavior of Loggerhead Shrikes in the agriculturally dominated Lower Mississippi Alluvial Valley of Arkansas. Over 3 winters, we observed behavior of Loggerhead Shrikes and found that they spent most of their time perched and scanning for prey (81%), mainly from utility wires (68% of used perches). On average, they made 14.9 ± 1.2 foraging attempts/hr and focused their efforts mostly in right-of-way grasses and adjacent agricultural fields. Overall, individual foraging success rates averaged 58%, did not differ amongst microhabitats, and were comparable to rates reported for breeding Loggerhead Shrikes from other habitats at similar latitudes. Arthropods were the most frequently captured prey (76%; based on direct behavioral surveys), and anurans were the most commonly cached prey (43% of observed cached items). In total, our study highlights the importance of utility wires and rights-of-way for foraging and arthropods as food sources, throughout even the coldest months of the year at this latitude, and increases our understanding of the behavior and ecology of the Loggerhead Shrike in these contexts.