Pomarine Jaeger (Stercorarius pomarinus), San Carlos Lake, Pinal County

This Pomarine Jaeger was photographed by Keith Kamper on 14 November 2014

Pomarine Jaeger is a review species and juvenile jaegers pose an ID challenge, particularly at a distance. The bird was also recorded in three counties at the lake, Gila, Graham, and Pinal, and would be the first record for each of the counties. It was observed by Keith Kamper, Patty Tersey and Doug Jenness.

Pomarine is the rarest jaeger species in Arizona, with only ten accepted records.

This intermediate juvenile jaeger exhibited a heavy, bulky body, with a "barrel-chested" appearance, broad-based wings, and a rounded head. The bill was thick and appeared to be strongly bi-colored even at a distance (darker near the tip). Overall coloration was brown, head and nape appeared uniform in color, with no streaking. There were pronounced pale bases of the underprimary coverts resulting in a small crescent under each wing, creating a "double flash" typical of Pomarine Jaeger. Coverts appeared paler than the flanks, and the upper and undertail coverts were strongly barred. Central tail feathers barely jutted out beyond the others, were blunt, not tapered, nor as long as one would expect in Parasitic. In flight, in direct comparison with Ring-billed Gull, when not pursuing that species with prey items, the wingspread appeared slightly larger. Transiting flight wingbeats appeared slow and deep, not as quick as one would expect in Parasitic. All of these characteristics are consistent with Pomarine rather than Long-tailed or Parasitic jaegers.

14 November 2014, photo by Keith Kamper