ML130238811

Age

Not specified

Sex

Not specified

Observation details

NAB 65: 143 Great Black-backed Gull (Larus marinus) Barrow, Alaska October 8¿9, 2010 Andrew W. Piston, PO Box 1116, Ward Cove, AK 99928 On October 8th, while birding in Barrow with Steve Heinl and Jerry Koerner, we discovered a first cycle Great Black-backed Gull (Larus marinus) feeding on the remains of Bowhead Whales that had been cleaned the day before near the end of the road towards the point in Barrow. When we first found the bird we initially figured it was most likely a first cycle Vega Herring Gull, but as we continued to observe the bird we began to realize the bird had features inconsistent with any Herring Gull. After further study we identified the bird as a Great Black-backed Gull. Almost all the gulls feeding at the whale cleaning site were various aged Glaucous Gulls (Larus hyperboreus), so this gull was readily apparent with its dark wing tips, all black bill, and checkered appearance of the back and wings. Although we initially thought the bird was likely a Vega Herring Gull, the bird¿s large size started raising questions in our minds. All the surrounding gulls were Glaucous Gulls, which on average are the largest gulls typically seen in western North America. The bird in question was as large as all the Glaucous Gulls when standing, but when it took flight the bird appeared massive and clearly stood out as having the wider wingspan than any of the accompanying Glaucous Gulls. Giving an added appearance of general bulk was the slow wing beats the bird used in flight, which combined with the large wings, helped add to the overall larger look of this bird. Another feature that caused us to start questioning the identity of this bird was the massive bill. Although I don¿t have any experience with Vega Herring Gulls, the bill size and shape was unlike any herring gull I have seen and appeared to be structured more like one would expect from a Western Gull¿massive and thick. The bill was clearly larger than all the surrounding Glaucous Gull bills and at one point I found myself thinking that the nearby Glaucous Gulls appeared small billed by comparison. Overall the birds color was pale gray with a black checkering across the back and wing coverts. The bird did not have any of the brownish tones one would expect on a 1st cycle herring gull. The birds head was whitish, or light gray, with a black smudge behind the eye and a relatively flat forehead leading to a massive all black bill. The upperwing pattern matched that of a Great Black-backed Gull, with fairly uniform dark primaries and no pale window on the inner primaries as one would expect to see on a similar aged Herring Gull. The underwing showed pale flight feathers that stood out from the darker patterned underwing coverts. The tail had a dark band that was widest at the center and narrowed towards the outer retrices. The rest of the tail and upper tail coverts were whitish with some small dark markings that were most numerous near the dark tail band.

Technical information

Model

C765UZ

ISO

71

Focal length

63 mm

Flash

Flash did not fire, auto

f-stop

f/3.7

Shutter speed

1/320 sec

Dimensions

788 pixels x 600 pixels

Original file size

131.23 KB