Kelp Gulls in the Caribbean

Jump down to the Barbados Gull. Photos courtesy of Martin Frost.

The gull from Trinidad came to my attention due to Floyd Hayes, Lecturer in Zoology, Department of Life Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago. Floyd writes:

I first saw this gull during the last half hour of daylight on 8 July 2000, on the eve of my departure to Guyana for a week. Graham White relocated the bird on 9 July and managed to get some decent photos on 10 July. Nobody has seen the bird since. Neither Graham nor I claim any expertise in gull identification. We've basically been having fun the last several years examining the flocks of up to 3000 or more Laughing Gulls that congregate on the west coast of Trinidad, and hope that those of you who live here will join us more often in keeping track of the rarities that trickle through.


The Lesser Black-backed Gull (LBBG) is the second most common species of gull in Trinidad, with at least six different birds present in 1997-1998, three in 1998-1999, and eight in 1999-2000. At least three LBBGs, including an adult and two 2nd-summer immatures, have lingered all summer--providing the first summering records. Fortuitously they were present when the mystery gull appeared, facilitating comparisons.


The mystery gull is dark enough to be an intermedius or fuscus (races of LBBG, L. fuscus), as well as several other species of gulls including Great Black-backed Gull (GBBG) of the northern hemisphere and Kelp Gull (KEGU) of the southern hemisphere. We could not discern much, if any, contrast between the mantle and the wingtips, though a few photographs suggest that the mantle is slightly paler. The mystery gull appears too small and obviously yellow-legged to be a GBBG, but it does resemble a KEGU. The latter species has been recorded sporadically in North America since 1989, and a few have been breeding and hybridizing with Herring Gulls off the coast of Louisiana. One could plausibly show up in T&T.


Both the body and bill of the mystery bird appear perhaps 10-15% larger than an associating adult graellsii LBBG, but only slightly larger or equal in size to the two 2nd-summer graellsii (these birds are steadily molting into 3rd-winter plumage, with dark-gray rather than black patches of feathers on the back, similar in shade to the adult graellsii). The bird usually adopted an erect, stretched-neck posture that enhanced our impression of its large size and gave it a small-headed appearance. From what we have read and the photographs we've examined, we think that fuscus LBBG, which apparently is always smaller and trimmer than graellsii LBBG, could be eliminated as a contender. Perhaps we're way off, but I think that leaves us with either a KEGU or an intermedius LBBG as potential candidates. If so, either taxon would be new for the region.


Neither Graham nor I were aware of the importance of leg coloration when we saw the bird. I described it as "yellow" and Graham described it as "yellow--hint of greenish yellow." The legs look fairly bright yellow--brighter than in the KEGU photos we have seen. When the photos are examined through a dissecting microscope, the legs often appear to be the same shade of yellow as the bill, but sometimes a bit duller. Graham feels quite certain the legs were slightly duller in color than the bill; I have no recollection. The yellow in the photos on my screen appear slightly brighter than in the real photos, but comparisons between bill and leg colors may be valid. A reddish orbital ring and a pale iris are apparent in several photos when viewed through the microscope; these are consistent with both intermedius LBBG and KEGU.


We could not find any white on the tips of the primaries of the mystery bird, and none can be detected in the photos; obviously the white is worn off. Nevertheless, the plumage of the mystery bird was relatively fresh compared with the heavily worn adult graellsii LBBG. The projection of the wingtips beyond the tail appears similar in all of the large gulls. The bill of the mystery gull seems a bit heavy, but shaped similar to that of the graellsii LBBGs. I thought the mystery gull had proportionately longer legs, but the photographs don't seem to demonstrate any such differences.


In summary, the mystery gull's body seems big for an intermedius LBBG, which is supposed to be smaller (with some overlap) than a graellsii LBBG, but perhaps not big enough for a KEGU. The mystery gull's bill seems heavy for an intermedius LBBG, which is supposed to be longer and more slender than that of a graellsii LBBG, but perhaps not heavy enough for a KEGU. If the mystery bird is an intermedius LBBG, perhaps it is a large male. If it is a KEGU, perhaps it is a small female.


Here are my [Floyd's] comments on the photos (below):


#1. Note the black upperparts, heavy bill, wings projecting beyond the concealed tail, and yellow legs.


#2-3. Note the blacker upperparts, larger size and heavier bill of the mystery gull (left) compared with an adult, alternate-plumaged graellsii LBBG (right). The graellsii LBBG is partially obscured by vegetation in the foreground, resulting in greenish hues. The two gulls in the foreground are obviously Laughing Gulls.


#4. Note the similarity in size and projection of wingtips beyond the tail of the mystery bird (right) and 2nd-summer graellsii LBBG (left). Also note the subtle difference in proportions, with the mystery gull's posterior appearing more attenuated and the head relatively smaller.


#5. Here is a direct comparison, from front to back, of the adult graellsii LBBG, the mystery gull, and a 2nd-summer graellsii LBBG. Compare the wingtip projection of the latter two.


#6. This is the closest shot of the mystery gull.


#7. Again, compare the mantle coloration and sizes of the mystery gull (right) and adult graellsii LBBG (left).


#8. This excellent shot of the underwing reveals only a faint secondary bar. Note also the bright yellow legs and feet.


#9. A closeup of the head.

Then later, after an exchange of emails, Floyd wrote:

Though some gulls, no matter how many feathers are photographed, may remain a mystery indefinitely, it appears that the "Trinidad Mystery Gull" is no longer a mystery. The obvious consensus among 11 gull aficionados who commented on the photographs was that it was a Kelp Gull. Many argued that the size and shape eliminated the darker forms of Lesser Black-backed Gull, and several (with one exception) argued that the small size and yellow legs eliminated Great Black-backed Gull. Our own concerns about the brightness of the legs were echoed by others, but adequately addressed by a few, most notably Donna Dittmann who has been studying the Louisiana Kelp Gulls. The absence of white on the primaries (also not seen by Graham White or myself in the field) puzzled a few; presumably the white has worn off.

The worn primaries and bright soft parts of this apparent Kelp Gull suggest it is in alternate plumage and has been present for some time in the Northern Hemisphere rather than a recent vagrant from the Southern Hemisphere. Earlier in the summer Graham noted three different adult LBBGs present, but only one stuck around all summer. I had fun imagining the KEGU nesting with an adult LBBG on Soldado Rock (huge colony of Sooty Terns and Brown Noddies), about 80 km to the southwest--just think of what the hybrid offspring would look like! I did hear the KEGU give a long call once (sorry, but I was so busy looking at the bird and writing descriptions that I forgot to describe the call), but never heard such a call from a LBBG; surely it was in an aggressive rather than courtship context.


The Kelp Gull is still around [December 12, 2000], though very elusive, wandering along 25 km of coastline. In late September and October it had some large white patches on the wing coverts--obviously molting, which should be consistent with a bird from the Northern Hemisphere. Its legs are still fairly bright yellow, though with a definite green tinge. It's now been seen during 5 of 13 trips by birders to San Fernando, 25 km S of where we first saw it in Waterloo.

As always, click on the thumbnail to load the full image.

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Floyd Hayes also alerted to me this gull. The bird showed up just last week [~December 9, 2000] and it's definitely a different bird than the Trinidad bird above. The Barbados observers are unable to make out any orbital ring!

As always, click on the thumbnail to load the full image.

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since December 16, 2000 (Thanks WebCounter!)