The Loggerhead Shrike is the only one of the world's thirty species of true shrikes that occurs exclusively in North America. Like other shrikes, it inhabits ecotones, grasslands, and other open habitats and feeds on a variety of invertebrate and vertebrate prey. Compared to most birds, its head is large in proportion to its body size-hence the name Loggerhead, which also means "blockhead." Popular names for this species include butcherbird, white-rumped shrike, French/Spanish mockingbird, and thornbird.
Throughout most of the southern part of its range, the Loggerhead Shrike is resident; northern populations are migratory. Where resident, this species usually lives in pairs on permanent territories. Some pairs spend the entire year on a single territory; outside the breeding season, mates may defend neighboring territories, which are coalesced at the beginning of nesting.
This shrike, like others, is a small avian predator that hunts from perches and impales its prey on sharp objects such as thorns and barbed-wire fences. Although such predatory behavior mimics that of some raptors, impaling behavior represents a unique adaptation to the problem of eating large prey without benefit of the stronger feet and talons of raptors. In addition, the hooked bill, flanked by horny tomial projections and functionally similar to the notched upper bill of falcons, further sets shrikes apart as distinctive in the order Passeriformes. Being both passerines and top-level predators, these birds occupy a unique position in the food chain.
Despite its wide distribution, the Loggerhead Shrike is one of the few North American passerines whose populations have declined continentwide in recent decades. Changes in human land-use practices, the spraying of biocides, and competition with species that are more tolerant of human-induced changes appear to be major factors contributing to this decline.