English and Scientific names:

Great Black-backed Gull, Larus marinus

Number of individuals: 

1 in 1st basic

Locality: LOUISIANA: 

Cameron Parish

Specific Locality:

East Jetty

Date(s) when observed:

10 September 2005

Time(s) of day when observed:  

16:10-16:30

Reporting observer and address:

Robert C. Dobbs
Fort Collins, CO

Other observers accompanying reporter who also identified the bird

Danny M. Dobbs

Light conditions (position of bird in relation to shade and to direction and amount of light):

Relatively bright, but soft light (cloudy conditions)

Optical equipment: 

Swarovski HD-STS80 spotting scope

Distance to bird(s): 

200-300 m

Duration of observation:

20 min

Habitat: 

Sandy beach, ca. 200 m east of jetty

Behavior of bird: 

Resting

Description:

Massive gull, 3-4 x size of Laughing Gull (direct comparison of resting birds); very heavy, all black bill, except for small pale area at base of mandible; legs flesh-colored.

Plumage: all white head (with very little, very faint brownish tinge on nape); underparts white, with sides of breast and breast most clearly visible (sides of breast very white, but also showed very little, very faint brownish tinge to some feathers); wing coverts, scaplulars, and back mottled pale gray and darker brownish-gray (producing somewhat checkered look) ; primaries very dark--missed details when bird briefly stretched wings; all white rump.

Voice:

Bird did not vocalize.

Similar species:

Among subadult plumages of the "large" dark-primaried gulls, only Great Black-backed (to the best of my knowledge) has the combination of almost immaculate white head, white underparts, and very large, deep bill. I considered 1st year Kelp Gull, which apparently has a rather white head and large bill, but such a bird should show darker underparts, a more solid dark back, and is smaller.

Photographs or tape recordings obtained?

Unable to obtain photos

Previous experience with this species: 

No previous experience with subadults of this species.

Identification aids:

at time of observation: = Sibley Guide to Birds
after observation: = miscellaneous photos online

This description is written from: 

Notes taken at time of observation

Are you positive of your identification? If not, explain: 

 

95%--less than 100% simply due to lack of previous experience with subadults of this species.

Reporter: 

Robert C. Dobbs

Date and time: 

20 September 2005, 10:00 am