The historical distribution of Loggerhead Shrikes in Alberta has not been well documented, but has evidently changed over the last century in response to human land use patterns. Shrikes occur throughout the
Grassland and Aspen Parkland regions, where frequent fires reduced woody encroachment and provide suitable foraging and nesting
habitat. A reduction in fire frequency that accompanies human settlement may reduce habitat suitability in the Aspen Parkland, but the simultaneous intensification of agricultural activities in more northerly areas may have encouraged the northward expansion of the breeding range in Alberta, and elsewhere on the Canadian prairies. The northerly range expansion reached a peak by the mid-1950s, when the species was reported breeding at Fairview and Falher in the Peace Parkland. Loggerhead Shrikes were also reported as far west as near
Waterton Lakes National
Park, although the late date of this record (28 August 1939), suggests that it may have been of a migrating individual.
Since the 1950s, the breeding range of the Loggerhead Shrike in Alberta has contracted southward. Breeding Bird Surveys
(BBS) last detected Loggerhead Shrikes in the Athabasca region in 1973, and by the early 1980s, almost all reports of Loggerhead Shrikes along BBS routes were from areas south and east of Drumheller. There is also a concentration of records in the extreme southeastern part of the province. Records in the Aspen Parkland are relatively sparse, although a few records extend as far north as Athabasca and Lac La Biche, and west to Drayton Valley and Sundre.
Reprinted from Alberta Wildlife Status Report No. 24 (1999), with permission
from Alberta Sustainable