Sunday, September 5, 2010

Recently arrived gull?

Last friday (september 3rd), I went to Panama Viejo and Costa del Este in Panama City, this time with Osvaldo Quintero, just to check out the hundreds of shorebirds present in the mudflats. The day was cloudy and by the time when we arrived to Panama Viejo, it began to rain. Not only that, the 13-feet high tide was not enough to push the birds close to shore, so we did not get many photographic chances. In any case, we walked towards the beach, finding immediately the now-usual suspects: Western, Semipalmated, Least and Spotted Sandpipers all around, plus Black-bellied, Semipalmated, Collared and Wilson's Plovers. Then, I saw an agitated shorebird running from one side to the other, with a long and thin bill... a Wilson's Phalarope. I was surprised because that was my first phalarope in more than ten years! It was wearing its winter (basic) plumage and soon flew behind the mangroves. I got awful photos of the bird (as you can see... it was too far away for my lens), but Osvaldo's are better. Anyway, you can see the characteristic silhouette and thin bill of the bird. We decided to visit Costa del Este (not before watching one, of two, Wood Storks leaving the mangroves where they were resting). In Costa del Este the things were not better, we only found distant shorebirds... but two PETRELS were carefully inspecting them with their scopes. We only stayed for a while, and decided to return to Panama Viejo to see if the weather improved. Back in Panama Viejo, we noticed among the Laughing Gulls and the Royal and Gull-billed Terns, a bigger gull with darker mantle. Through my binoculars I noticed the not-so-heavy-looking and slender beak, with not a pronounced gonydeal angle, dusky with yellow tip, the dark grey back, the white (unmarked?) head, underparts and tail, and the yellow legs: a Lesser Black-backed Gull. It was too far away (like the phalarope), but my pics still show most of these marks (you can enlarge the photos by clicking on them).

In the last photo, you can notice its relative size compared to the nearby Laughing Gulls, and its darker mantle (compare the colour with that of the Black-necked Stilt standing in front of it). You can see also that this bird retains pale (younger) secundaries feathers in the closed wings. When it took off, it flew directly away of us, showing pale secundaries and inner primaries (the outer primaries were darker than the mantle) and a slightly dark smudge to the end of the tail.

This was almost an adult bird, and is the earliest date that I see this rare gull in Panama (and it seems that the earliest date recorded before was september 6th, 1997). I'm not an expert, but I'm calling it a third-winter (basic) Lesser Black-backed Gull probably molting from its 3rd-alternate. What do you think?

Ending the day, we went to the Panama Viejo's Visitors Center where we saw other Wood Stork, a Great Blue Heron (recently arrived too?) and, under the "curious thing" tag, a Ruddy Turnstone walking along with a Rock Pigeon. Is not curious?

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