Relationship of Vertebrate Prey Size to Transport Mode and Distance in the Northern Shrike

This report presents experimental data on the transport of vertebrate prey by the Northern (Great Grey) Shrike (Lanius excubitor). The species is known to use three modes of transport: carrying prey exclusively with the bill, exclusively with the feet, and by transferring the prey from bill to feet while in flight. Shrikes often transport their prey a short distance from the point of capture (initial distance), followed by the longer flight to the impaling site (long distance). We found that the overall distance (initial plus long) and long distances, but not the initial distance, decreased with increasing prey weight. Greater weight of the prey coincided with reduced use of bill-only transport. The results reveal that Northern Shrikes are well adapted to carry their most common vertebrate prey, voles of the genus Microtus.