Despite their reputation for impaling reptiles on thorns and barbed-wire fences, in many parts of their range, the diet of the Loggerhead Shrike (Lanius ludovicianus) consists mainly of insects. Spiders, such as the one captured by this shrike in Tooele County, Utah last month, make up a smaller proportion of the diet (roughly 4%).
One thing I found interesting upon reading the Birds of North America account on the Loggerhead Shrike: the hypothesized reason behind their propensity to impale large prey items on thorns and spines.
Shrikes are songbirds, but unlike other songbirds, they will kill larger vertebrates such as lizards, birds, and small mammals that are usually taken by raptors. Since shrikes have small perching feet similar to other songbirds they lack the talons and grasping feet of raptors, and it is for this reason that it is thought they impale their prey: to act as a holding mechanism for prey that is larger than their morphology dictates they should be able to eat.
A pretty amazing behavioral adaptation!
Yosef, Reuven. 1996. Loggerhead Shrike (Lanius ludovicianus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/231
Tags: 52-week project, bird, Lanius, Lanius ludovicianus, loggerhead shrike, prey, shrike, spider, utah