Vagrant Gulls at Costa del Este

Rosabel Miró, Chris Rhodes and Darién Montañez visited Costa del Este at 7:00 A.M. to look for interesting gulls on the puddles in the mud. The first stop was on a large, shallow pond to the left as you descend from the bridge across the Corredor Sur from Chanis, on a large plot of land between the new Colegio San Agustín and the houses. The most interesting bird there was what seemed to be an all-dark Green Heron. Ridgely mentions a melanistic phase found in the lowlands of Bocas del Toro, but Costa del Este is quite a long way from Bocas. We thought this bird was clearly a Green/Striated Heron after comparing it with the real Striated Herons that were all around the same pond. Its plumage was almost black, though, dark brown on the sides of the neck.
After that we stopped to watch a flock of gulls standing next to a large puddle next to the mouth of the canal that separates Costa del Este from the mangroves to the east. There was a Franklin's Gull, but the highlight was a possible juvenile Gray Gull. Its plumage was brown all over, slightly lighter around the face. It seemed to be the same size as the Laughing Gulls around it. When it flew we did not see any white trailing edge on the wings, but the tip of the tail seemed to be of a lighter color.
Then we stopped at another flock of gulls, on the plot of land between the Escuela Interamericana and the coast, next to the Corredor Sur as it heads towards Panamá Viejo. This flock had a Ring-billed Gull, but the highlight was a Gray-hooded Gull. It also seemed to be the same size as the ubiquitous Laughing Gulls, but showed no trace of black in the nape. Instead, its head was white, with a light gray wash nape a faint gray ear patch. The mantle was also a lighter shade of gray than that of the Laughing Gulls, but the most evident difference was its bright red bill (black on the tip) and legs. In flight the differences were also obvious: a large white patch on the leading primaries separated the gray wings from its black tips, and there were white mirrors at the very tip.
After getting so lucky gullwise we decided to stop at the Parque Ecológico to look for Golden-Plovers and other grass sandpipers, but the only things that were around were a few Whimbrels.