Medium-sized, length 23 to 25 cm, wing span about 30 to 35cm, relatively long-tailed appearance. Typically perched atop a tall tree or shrub surveying its world. Adult gray above and white below, with contrasting pattern of black and white on wings and tail, black mask, and white rump. Heavy black bill toothed and hooked at tip. Sexes similar, although female may average slightly duller black in wings and have less pure-gray upperparts, sometimes discernible when mates seen together (Cade and Atkinson 2002).
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see Marks et al. 2016, Birds of Montana.
Western Hemisphere Range
In the Bozeman area, normal migration periods are October 15 to November 1 and March 10 to April 10, with a peak on March 25.
Nests throughout taiga and taiga-tundra ecotone of Alaska and Canada, where suitable trees or shrubs occur in association with open landscapes and in willow, alder and poplar stands that extend beyond spruce line into tundra zone. Winter range in areas farther south in southern Canada and U.S. Includes coastal wetlands and estuaries, savannas, forest edges, Great Basin shrub deserts and edge with forests, Great Plains and edge with forests and deciduous woodlands, especially where trees and shrubs planted as shelterbelts, and mixed agricultural-suburban-woodland associations of the former eastern deciduous forest region of mid-western and e. U.S. and s. Canada.
Mostly arthropods by number, but small mammals and birds, rarely reptiles, make up the bulk of the Northern Shrike's diet. Especially in winter, it is a determined pursuer of small birds and mammals (Cade and Atkinson 2002).
Nests in deciduous trees/shrubs built before new leaves develop, usually obvious and exposed at first, but concealed by new growth before young leave nest. Nests in conifers well concealed and protected by overhead cover. Eggs ovate to rounded-ovate, ground color grayish white to greenish white, usually heavily blotched or spotted. Clutch size is probably 4 to 6 eggs. Nest construction begins soon after arrival in late April- early May. In Alaska, earliest egg-laying May 5. (Cade and Atkinson 2002).