A family affair?

Sandwich Tern with Royal Terns

Here in Tortuguero, on the Caribbean coast of Costa Rica, Laughing Gulls have only been around in numbers since a week or two, but Royal Terns have been common at least since I got here, mid-October.

Yesterday afternoon, I walked out to the mouth of the Tortuguero River, where a number of them can usually be found.

About a third of the individuals in this group were banded. A little bit of online research showed me there's a considerable banding effort on the United States Eastern Seaboard each year, involving thousands of Royal Terns being banded in Maryland, Virginia and North Carolina. Go here for an account of a Honduran intern's experience banding Royal Terns with the Maryland Coastal Bays Program.

Four of the five banded individuals I saw can be seen in this photo. Even within the group, they seemed to associate more closely with each other, something I'd noticed with banded individuals in New Jersey and El Salvador also. According to the BNA account, Royal Terns are "highly social and gregarious throughout the year, assembling into compact flocks up to several thousand, often in family groups, but occasionally solitary outside the breeding season (Buckley & Buckley 2002, emphasis added).


References:
Buckley, P. A. and Francine G. Buckley. 2002. Royal Tern (Sterna maxima), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/700