Range map of Northern shrike.     Nonbreeding  Breeding  Migration  Year-round
BirdLife International. 2017. Lanius borealis (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T103718956A118775235. https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T103718956A118775235.en. Downloaded on 01 January 2019.
Cephas