Loggerhead Shrike (Lanius ludovicianus) is endemic to North America, being native to Canada, U.S.A. and Mexico. It is currently listed as Least Concern, because it has been considered to not approach the threshold for Vulnerable under any criterion. This species inhabits open areas with short vegetation and has been described as rare to locally fairly common (Yosef and International Shrike Working Group 2016). Hence it may not approach the threshold for Vulnerable under criterion C, but the species has been undergoing a steady decline.
Several ideas have been presented that may account for declines (see Lymn and Temple 1991), including pesticides (Anderson and Duzan 1978), loss of breeding habitat to agricultural land (though it has been concluded that this may not be limiting Loggerhead Shrikes [Brooks and Temple 1990]), West Nile Virus (Smallwood and Nakamoto 2009), and habitat loss and fire ant presence in wintering habitats (Lymn and Temple 1991). While the use of certain pesticides is now prohibited in U.S.A. the potential effects of other threats may be likely to continue into the future.
Data from the Breeding Bird Survey has suggested population declines of c. 24% (-30.5 to -17.5%) over 3 generations (10.8 years) (Sauer et al. 2014); thus the population trend is likely to be approaching the threshold for listing as Vulnerable under criteria A2ce+3ce+4ce. Therefore, it is proposed that the species be listed as Near Threatened under criteria A2ce+3ce+4ce; and we welcome any further comments regarding this proposed uplisting.
Anderson, W. C.; Duzan, R. E. 1978. DDE residues and eggshell thinning in loggerhead shrikes. Wilson Bull. 90: 215-220.
Brooks, B. L.; Temple, S. A. 1990. Dynamics of a Loggerhead Shrike population in Minnesota. Wilson Bull. 102: 441-450.
Lymn, N.; Temple, S. A. 1991. Land-use changes in the Gulf Coast region: links to declines in Midwestern Loggerhead Shrike populations. Passenger Pigeon 53: 315-325.
Sauer, J. R.; Hines, J. E.; Fallon, J. E.; Pardieck, K. L.; Ziolkowski, Jr., D. J.; Link, W. A. 2014. The North American Breeding Bird Survey, Results and Analysis 1966 – 2013. Version 01.30.2015 USGS Patuxent Wildlife Research Center, Laurel, MD
Smallwood, K. S.; Nakamoto, B. (2009) Impacts of the West Nile virus epizootic on the Yellow-billed Magpie, American Crow, and other birds in the Sacramento Valley, California. Condor 111(2): 247-254.
Yosef, R.; International Shrike Working Group 2016. Loggerhead Shrike (Lanius ludovicianus). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/60481 on 19 December 2016).