Population trends of the loggerhead shrike from the North American Breeding Bird Survey
North American Breeding Bird Survey data indicated a general decline in Loggerhead Shrike (Lanius ludovicianus) populations during 1966-1993. At the continental level, shrikes declined at an average rate of 2.9% per year. Average rates of regional declines varied from 2.5-3.4% annually. These declines were prevalent in most states, provinces, and physiographic strata. Only the Edwards Plateau, High Plains, and Great Plains Roughlands strata, and Colorado, Louisiana, Montana, and South Dakota apparently have stable breeding populations. Severe winter weather during 1976-1979 may have contributed to this decline in the eastern half of the continent, combining with other factors during the winter and breeding seasons that have been implicated in the rangewide decline of this species.