Black-legged Kittiwake (1 Viewer)

[Richard Klim]

Pacific subspecies pollicaris Ridgway, 1884 recognised for IOC World Bird List v3.2 (Draft).
www.worldbirdnames.org/updates/subspecies

Also recognised by Malling Olsen & Larsson 2003, Howell & Dunn 2007, HBW, BNA Online, Clements; but not by H&M3.

• Burger & Gochfeld 1996 (HBW 3).
  
  
• Hatch, Robertson & Baird 2009 (BNA Online):
  

  Geographic Variation
  Considerable geographic variation in body weights and wing lengths (see Measurements). Within nominate subspecies, w. Greenland and e. Canadian Arctic breeding birds show less black on wing tips than other Atlantic populations (Chardine 2002).
  Based on mtDNA control region sequence, genetic differentiation exists between Atlantic and Pacific populations, and to a lesser degree within Atlantic populations (Patirana 2000). Pacific and Atlantic separation also clearly seen in 7 nuclear microsatellite allele frequencies, but geographic variation in Atlantic was limited (McCoy et al. 2005). ...
  
  Subspecies
  Two subspecies recognized, both in North America. Widely distributed nominate race (R. tridactyla tridactyla) occurs in Arctic and Atlantic basins, R. tridactyla pollicaris in North Pacific. Nominate race generally has a shorter bill, slightly smaller overall, less frequently shows a well-developed hind toe/claw, less black in the primaries (Brown et al. 1975, Cramp and Simmons 1983, Sluys 1992, Chardine 2002, Helfenstein et al. 2004a).