As we are staying socially distant at home, the Least Terns are starting to migrate back to the Texas Coast to breed. The Least Tern is the smallest tern in North America. It’s also one of the few waterbird species that Gulf Coast Bird Observatory typically monitors during beach nesting bird season which begins in April and goes through the end of August. They have been observed nesting at Matagorda Beach, Bryan Beach, and sometimes at Dow Plant A. It is a species of high concern and interior populations are considered endangered due to its population declining.
Like other terns, the Least Tern’s body is mostly gray above and white below. We typically see them in their breeding plumage. They differ from other breeding terns by having bright yellow-orange legs, skinny yellow bill with a black tip, a black cap with a white forehead, and a black eye stripe. Their main diet is small fish and invertebrates. They like beaches, bays, estuaries, lakes, and rivers. They typically breed in open sandy, muddy, or gravelly spaces. In fact, they favor the parking lots at Matagorda and Dow which is unfortunate due to human disturbance.
Least Terns are considered colonial nesters, which means they tend to nest in very large groups. A colony can vary in size. Colony size can range from a few birds to as large as over a hundred birds depending on how much space they have. Last year, we observed at most 80 birds with 40 pairs in one colony nesting in a parking lot. The Least Terns nest in colonies to help protect themselves from predators thus safety in numbers.
During the breeding season, male Least Terns create nests called scrapes. Scrapes are small shallow bowls that the Least Terns create by scraping their bellies in the sand or gravel. In order to woo or attract a lady, the male Least Tern must offer her a fish and if she accepts, they will mate. Least Terns can lay one to three eggs. Both the male and female will take turns incubating the eggs until they hatch which usually takes 19 to 25 days.
The chicks are semi-precocial. This means that when they hatch, the chick’s eyes are wide open, they are fully feathered, and are able to move around within hours after hatching. Because their main diet is fish, the chicks still heavily rely on the parents for food. They also rely on the parents for shelter. The parents usually take turns caring of the chicks until they are able to fly, which is usually within 20 days of hatching.
During breeding season, Least Terns are highly protective of their nests and chicks. By nesting in large numbers, they are more capable of mobbing threats as a group. Mobbing can be in the form of squawking, pecking, or dive bombing/pooping on whatever is threatening them. Trust me, it’s like being in an Alfred Hitchcock movie. They can be highly disturbed by people, vehicles, and most importantly unleashed dogs. This is why we usually monitor and observe the colonies from a safe distance. Mobbing can deter Least Terns from incubating or protecting their nests and chicks which can cause the eggs to overheat and put both eggs and chicks at risk of predation.
So the next time you visit the beach, please be aware of nesting waterbirds like the Least Terns and give them plenty of space. If you don’t, then you might end up starring in your own horror movie covered in bird poop and, trust me, you don’t want that. On behalf of Gulf Coast Bird Observatory, thanks for reading and we hope that you are staying safe and healthy during this tough time.
Photos
LETE: Adult Least Tern in breeding plumage observed nesting at Matagorda Beach last year. Photo taken by Taylor Bennett
LETE chick: Least Tern chick observed at Matagorda Beach last year. Photo taken by Susan Heath.
