Sometimes called Northern Raven, this is the world's largest passerine. Eight or more subspecies in three clades usually recognized. Race breeding in Iceland and the Faroe Islands are C. c. varius characterized by white bases to their neck feathers usually visible only when the wind exposes them. This race averages slightly larger and less glossy than nominate C. c. corax of Northern Europe. A rare black and white morph found only on the Faroes was known as the "Pied Raven." It became extinct in the mid-twentieth century. Canon SX50 HS PowerShot.
References:
Boarman, W. I. and B. Heinrich (1999). Common Raven (Corvus corax), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.476
Haring, E., Däubl, B., Pinsker, W., Kryukov, A. & Gamauf, A. (2012) Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) - a first survey based on museum specimens. J. Zool. Syst. Evol. Res. 50(3): 230–246.
Madge, S. & Burn, H. (1994) Crows and Jays: A Guide to the Crows, Jays and Magpies of the World. Houghton Mifflin, Boston.
Marzluff, J. (2018). Common Raven (Corvus corax). 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 https://www.hbw.com/node/60808 on 12 September 2018).
Wikipedia contributors. (2018, August 30). Pied raven. In Wikipedia, The Free Encyclopedia. Retrieved 21:57, September 12, 2018, from https://en.wikipedia.org/w/index.php?title=Pied_raven&oldid=857289648