Texas - Terns in Context

Recently mentioned that the Black Tern is one of the smallest of the terns, but I didn't really place that in context. A photo from Rollover Pass on the Bolivar Peninsula may give you a better idea. Here 3 small molting Black Terns are in the center, dwarfed by 3 large Royal Terns to the right with their orange bills, and 2 medium-sized Sandwich Terns on the left, with yellow-tipped black bills. The Royal Tern at 20" is almost as large as the 21" Caspian Tern.

At Bolivar Flats the Black Terns were seen with the slightly smaller Least Terns. I thoughtlessly tried to frame the Black Terns by themselves, but did find the 2 small tern species together. The bill of the Least is yellow in breeding plumage, with a touch of black at the tip. No other terns seen in the U.S. have yellow bills.

Terns were once grouped with the Gulls in the family Laridae but DNA analysis convinced the taxonomists to give terns their own family, Sternidae. There are about 44 species of birds in the tern family, including 5 species with the name noddy.

We did get to see a few distant Gull-billed Terns on the Bolivar Peninsula along Yacht Basin Road, a new species for us. They have relatively longer legs that most terns, as well as thick black bills, and are not usually seen along the shore with other terns.

Thalasseus Terns - Royal and Sandwich

Having watched birds at Florida beaches for the last 10 years, I've wondered at how often many of the shorebirds choose to frequent heavily used areas, which of course includes many hundreds of miles of the Florida coast. Struck me that maybe over the years these birds have "learned" that humans not only pose no direct threat to them, but maybe even provide a level of protection from predators. At Venice Beach in April we watched a shoreline roost site of over 100 terns . Periodically beach-goers walking on the packed sand near the surf line would approach the terns, at which point the terns casually moved about 8' away from the surf to allow the walkers to pass, and then immediately closed ranks and reassembled closer to the water. Their comfort with human presence is surprising, and makes them ideal subjects for photography.

These Royal Terns (Thalasseus maximus) are part of the large group we watched. Their deep orange bills are shorter and thicker than those of our west coast Elegant Terns, but not as thick nor as red as the bill of the Caspian Tern. Royal Terns at 20" are large, almost the size of the 21" Caspian Tern, meaning that are as big as many gull species. Did you spot the interloping tern above?

Here's another look at the Royal Terns. The foreground birds are in alternate (breeding) plumage, while the one one to the rear is still working on getting its black cap:

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​About a dozen Sandwich Terns, Thalasseus sandvicensis,  gathered at the edge of the group furthest from the water, a pair with raised crests drawing our immediate attention. Their yellow-tipped black bilsl argues that this one should have been the one called "elegant". The blurred foreground bird isprobably a Caspian Tern.

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The above Sandwich were vocalizing, with crests raised, so I zoomed in. Quick switch to video mode captured a courtship dance, culminating in mating. The activity was not preceded by the usual courtship feeding, where the male present a fish to the female, but she seemed eager to explore a match none-the-less. Almost seemed like she was giving directions to male in the sequence that follows: Mating Sandwich Terns, Venice Beach, FL.

Let's turn to tern taxonomy (groan). In the 2000 edition of Sibley most of the terns were in the genus Sterna, with a few smaller terns in other genera. In 2006 they decided to split up the genus Sterna. 3 species were moved to the genus Thalasseus (Elegant, Royal and Sandwich), and others that moved to new genera,  including Caspian, Gull-billed, Least, Sooty and Bridled Terns. Check out the changes in one of my favorite sources:

Taxonomic Changes.

The 15" Sandwich Terns are said to be less aggressive than other tern and gull species, and often rely on bigger species like the Royal Tern to guard their crowded island nesting sites. The Royal Terns seem comfortable with their smaller cousins nearby.