Bird of the Month: Northern Shrike
By Andrew McCormick
Scientific Name: Lanius excubitor
Length 10 in
Wingspan 14.5 in
Weight 2.3 oz
AOU Band code NSHR
Like a sentinel, as described by its species name excubitor, Latin for watchman or guard, the Northern Shrike surveys its territory from a low perch on a shrub or post. With precision it hunts using a direct flight toward its prey-a small rodent or another bird-and dispatches it quickly by “pounding its bill into the base or back of the skull and the using its hooked bill severing the spinal cord between the neck vertebrae as falcons do” (Sibley). It will eat a large insect where it catches it, but will take larger prey to its larder and impale it on part of a fence, a twig, or fork between branches to be eaten later. This practice helps a shrike survive when there is heavy snow cover. Shrikes are in the genus Lanius, from the Latin lanio, to butcher referencing this method of eating impaled prey. Shrike is from the Old English scric, a thrush (Holloway).
The Northern Shrike is gray on the head and back with black wings and a black mask below the eye tapering toward the bill, which is black, long, heavy and hooked. It is closely related to the Loggerhead Shrike L. ludovicianus which is found mostly in the central and southern United States. In flight the Northern Shrike can be confused with the Northern Mockingbird where they are present. The white wing patches on the shrike are smaller than the mockingbird’s and are restricted to the primary feathers.
The shrike is a unique combination of songbird and hawk. In spring it will sing melodiously from a perch in a manner similar to a catbird including mimicking other songbirds. It is not a friend to other birds, however. The list of birds included in the diet of shrikes forms an impressive list including American Goldfinch, Pine Siskin, redpolls, crossbills, Evening Grosbeak, American Robin, chickadees, swallows, Blue and Gray Jays, Northern Cardinal, Downy and Hairy Woodpeckers, Mourning Doves, titmice, Bushtit, kinglets, European Starling, Yellow-rumped Warbler, and Savannah, Fox, Song, White-throated and Golden-crowned Sparrows (Cade & Atkinson). Its behavior of impaling birds on twigs probably evolved because unlike a raptor its feet are very weak and not suitable for catching or holding prey once caught.
The Northern Shrike breeds in the tundra and migrates to southern Canada and the northern United States where it can be found in open fields and wooded areas. It will head north in March where it will make an open cup nest of twigs, grass, moss and feathers. A clutch of 4-7 pale gray or greenish-white eggs with spots of varying colors is deposited and incubated for about two weeks. Both parents feed the young and first flight occurs about three weeks after hatching (Kaufman).
Worldwide there are 100 species of birds in the Lanidae Family but only about 30 are “true shrikes” (Alderfer). Global populations of shrikes are suffering as open fields are developed for agriculture and insect populations are reduced by spraying. The North American population has not been studied well.