Return to Conservation Biology Research on Birds
Eliason, B. 1996. Statewide survey and habitat protection for the loggerhead shrike in Minnesota. Final report by the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 7+ pp.
The loggerhead shrike (Lanius ludovicianus) historically bred throughout the United States, southern Canada, and northern Mexico. Declines in loggerhead shrike populations have been recorded in all areas of the bird's breeding range. The most severe declines have occurred in New England, where the species has been virtually extirpated. Significant declines have also occurred in the Midwest.
Once considered a common inhabitant of the agricultural region of Minnesota, loggerhead shrike populations have declined so severely that the species has been designated as threatened under the state endangered species statute. The last intensive statewide survey for the loggerhead shrike in Minnesota was conducted in 1986 and 1987, when University of Wisconsin graduate student Bonnie Brooks located 29 and 19 pairs in these years in 12 counties. In 1989, the MNDNR initiated a statewide monitoring program based on the results of Brooks' project. The monitoring methodology involved point surveys conducted at 1/2 mile intervals along 8 routes located in areas of historical breeding concentrations. This monitoring program documented a dramatic decline of this species along the survey routes between 1989 and 1994. This apparent decline was difficult to interpret for several reasons. Vegetation changes and conversion of other land uses had resulted in changes in habitat suitability along the survey routes. In addition, casual observations of shrikes in the vicinity of the survey routes suggested that more birds were present than were being detected by the methodology. Concerns about the validity of the monitoring methodology lead to the initiation of the current project.
The primary purpose of the 1995-96 project was to determine the current distribution and abundance of the loggerhead shrike in Minnesota to provide a basis for monitoring, further research, and the development of a recovery/management plan for the species. At the same time, the project provides comparisons of the efficiency and effectiveness of various methods of locating shrikes. In addition, because the largest known concentration of active shrike territories occurs in Dakota Co., a portion of the Twin Cities metropolitan area where rapid development is occurring, there is also a critical need for immediate habitat conservation measures to preserve shrike habitat. Therefore, a third objective of the current project was to offer technical assistance to landowners to maintain and enhance existing pasture land known to harbor loggerhead shrike territories.