By Lewis Young
The Northern Shrike is a solitary “masked hunter” that may be found in the northern U.S., including the Flathead Valley, during the winter. Its scientific name is Lanius excubitor and means “butcher watchman.” It is a pale gray bird with lightly barred under-parts and black wings, tail, and mask. The black wings have a distinctive white patch that can be seen when perched or flying and the tail has white outer feathers. The tail often bobs when perched. The black mask runs from the base of the bill, through the eye and well beyond. The bill has a distinct hook. Wingspan is about 12-14 inches and length is about 9-10 inches. Juveniles are brownish above and more heavily barred than adults. Immatures are somewhat intermediate in color but retain barring on under-parts until spring. A similar species, Loggerhead Shrike, breeds mainly in eastern Montana but winters farther south, whereas the Northern Shrike does not breed in Montana but winters here.
Northern Shrikes sing a medley of short liquid trills, whistles and harsh notes and often mimic the calls and songs of other birds, such as Blue Jays, Gray Catbirds, American Robins, and Song Sparrows. The call is a harsh shek-shek or a grating jaaeg. Both male and female Northern Shrikes sing throughout the year. The male sings especially in late winter and early spring.
Northern Shrikes live in semi-open country with lookout posts in the form of trees, shrubs, or other structures. They breed in the far north in Canada and Alaska in partly open or scattered spruce woods and in willow and alder scrub along streams or edges of tundra. Winter habitat is similar semi-open areas or sometimes in open grassland with a few high perches, but they seem to prefer some brushy areas nearby. They winter widely across the U.S. and southern Canada from coast to coast and as far south as northern Texas and New Mexico. Southern range limits and numbers on winter range vary unpredictably from year to year.
Northern Shrikes prey on insects, rodents, snakes, and small birds. They scan the countryside from a perch, then swoop down on prey with a direct flight. Occasionally, they may hover in the air above potential prey. Prey is seized near the ground with feet or bill and vertebrates are killed by biting through the neck. Wings, spines, and stingers are removed from insects. Food may be impaled on thorns, barbed wire, or hung in the crotch of a limb at an area called the larder. Besides being stored for later eating, the larder is believed to be also used for marking territories and attracting mates. Such behavior was characterized by early observers as “wanton killing,” but storing excess prey to eat later is an adaptation for surviving periods of food scarcity.
Nests are usually placed in a low tree or large shrub 6-15 feet off the ground. Probably built by both sexes, the nest is a loosely made, bulky open cup of twigs, grass, bark strips, and moss lined with feathers and animal hair. The nest is an open cup, but it is so deep that while incubating, the female is completely out of view except for the tip of her tail.
Clutch size varies from 4-9 eggs that are pale gray or greenish white, spotted with brown, olive, and gray. Incubation is mostly or entirely by the female and lasts 15-17 days. When born, the young have little down and are totally dependent on the parents. Both parents feed the nestlings, which leave the nest 19-20 days after hatching and then are tended by parents for several more weeks.
An odd historical note is that in the 1870’s, when the house sparrow had just been introduced from Europe, a warden was hired to shoot Northern Shrikes on the Boston Common in winter to protect the sparrows!
Currently there are no known conservation concerns. Population trends are difficult to assess because of the Northern Shrike’s rarity and remoteness of its breeding habitat; however, large areas of suitable breeding habitat in Alaska and northern Canada are protected. Currently the Northern Shrike is not on the U.S. Fish and Wildlife Service’s list of Birds of Conservation Concern, nor on the United States Watchlist, which is a joint project of the American Bird Conservancy and National Audubon Society.
Northern Shrikes, although not numerous, may be spotted fairly easily in the Flathead Valley in winter by looking for perched birds in prominent spots in mostly open areas. Trees, shrubs, fence posts, power lines and power poles overlooking open areas are good places to look. Enjoy them while they are here!