Loggerhead shrike

The loggerhead shrike is widely distributed throughout North America. They occur from southern Canada throughout the United States south to Mexico.

Loggerhead shrikes inhabit a variety of open areas. Habitat types include short-grass pastures, weedy fields, grasslands, agricultural areas, swampy thickets, orchards, and right-of-way corridors. Shrikes occupy sites that contain hedgerows, scattered trees or shrubs, and utility wires or fence posts. They use these features as perches. Nests are often located in trees or shrubs bearing thorns. Some preferred species include, hawthorns (Crataegus spp.), osage orange (Maclura pomifera), and multiflora rose (Rosa multiflora). Red cedar (Juniperus virginiana) may also be used for nesting. Similar habitats are occupied year-round.

Loggerhead shrikes are opportunistic predators. They consume insects, small mammals, songbirds, snakes, frogs, lizards, and even small turtles. In summer, shrikes eat a large number of insects, small mammals, and songbirds. In winter, small mammals and songbirds comprise most of their diet.

Shrikes hunt from perches like fence posts and telephone wires. They perch high above their habitat to look for prey. When prey is sighted shrikes pounce on and kill it instantly.

Since shrikes lack talons they utilize thorns and other sharp objects to impale their prey. They use these sharp objects to anchor and immobilize their prey when they feed on them. Impaling prey allows shrikes to cache or store food and catch prey that would otherwise be to large to handle.

Loggerhead shrikes occupy large territories that are vigorously defended. During courtship males perform aerial displays and deliver food to potential mates. Male and female shrikes gather nesting material, but the female always builds the nest. The female builds the nest in a thorny shrub or tree that provides cover. Nests are constructed of twigs, weeds, bark, and are lined with grasses, lichens, moss, string, hair, or feathers.

In mid-April females lay 5 to 6 brown speckled-white eggs. She starts to incubate after the first egg is laid. She incubates the eggs for 16 to 20 days. The male provides all the food during this period. The young hatch asynchronously, or in the order that they are laid. This adaptation results in young that are staggered in ages. During years when prey is limited only the oldest and strongest young may survive. When the young hatch the females broods them closely. They are born blind and naked, or altricial, and are completely dependent on the adults. At 17 to 21 days old the young leave the nest but are still unable to fly. By 30 days the young fledge or fly for the first time. After fledging the young practice catching prey and learn skills that they will use for the rest of their life. They are fed by the adults for an additional 3 to 4 weeks after they fledge. Juvenile shrikes breed the following spring.

The clearing of eastern forests for agriculture during the 19th century created habitat for several species of grassland and edge birds, including the loggerhead shrike. The abundance of small farms, pastures, and hedgerows in the northeastern United States enabled this shrike to expand its breeding range. When mechanized agriculture began to expand large monocultures of agriculture operations, high quality shrike habitat was diminished. Many open areas were also lost to development or matured into forests. Consequently, the breeding range and the number of loggerhead shrikes in the Northeast began to decline by the early 1960’s. The heavy use of pesticides, particularly DDT, accumulated in the prey of shrikes and resulted in eggshell thinning, reproductive failure, and contamination of adults and young.

Severe habitat loss and pesticide contamination was disastrous to nesting loggerhead shrikes in the northeastern United States. Since the 1970s, loggerhead shrike numbers have plummeted and breeding populations have been extirpated from much of this region. Declines were observed in breeding bird population from the late 1960s into the late 1990’s. Declines were also observed on the wintering areas of shrikes from the late 1950’s to late 1980’s. This shrike was listed as a Nongame Migratory Bird of Management Concern by the U.S. Fish and Wildlife Service in 1982 and 1987.

Due to severe population declines and habitat loss, the loggerhead shrike was listed as an endangered species in New Jersey in 1987. Rare throughout much of the Northeast, the loggerhead shrike is also listed as endangered in New Hampshire, Vermont, Massachusetts, New York, Pennsylvania, Maryland, and Virginia. Habitat loss is still considered to be the main threats to loggerhead shrikes in New Jersey today.