A FEISTY ROYAL TERN

Above you see a bird species occasionally showing up along the beach here. The birds are terns, not gulls. The family Laridae comprises the Gull Subfamily, the Tern Subfamily and the Skimmer Subfamily. Terns differ from gulls in that gulls possess relatively small, stout, hooked bills and, usually, rounded tails, while the bills of terns average somewhat larger, are pointed instead of hooked, and tern tails are forked.

The birds in the picture are Royal Terns, STERNA MAXIMA, and a confrontation seems to be taking place. When I showed the picture to Marcia, the hotel owner, she told me that a while back an ornithologist staying at the hotel told her that immature Royal Terns are famous for "acting out" in front of their parents. Sometimes the parents reciprocate with a bit of defensiveness but other times they just stand calmly and let the tantrum pass. I can't say for sure what's happening in the picture -- even whether the angry-looking one is an immature or not -- but learning this about immature Royal Terns makes tern watching more interesting now.

Royal Terns are one of three Mexican-tern species with black crests, and in the picture you can see how the crests can be raised. Usually the crest points backward giving the bird's head a flat-topped, swooped-back look but the bird in the picture with his crest erect looks almost horned.

As the picture shows, Royal Terns in winter plumage have white foreheads. Only for a short time during the species' breeding season does a solid black cap develop. Royal Terns are very similar to Elegant Terns, but Elegant Terns don't occur on Mexico's Gulf/Caribbean side, only on the Pacific. Royals can most easily be confused with Caspian Terns, but that species is larger, has a blood-red bill instead of the Royal's orangish one, and its tail is less deeply notched.

Royal Terns are strong flyers and strictly limited to saltwater, unlike some tern species who range inland. Royals occur from northwestern Mexico and the eastern US south to Peru and Argentina, and locally in western Africa.

Most tern species feed by plunge-diving for fish near the surface.