The return of the least terns…Part 2.
By: Olivia Morpeth
Least terns are one of the colonial nesting species here on Alabama’s coast. Their colonies can range from just a few birds to hundreds of pairs and nests! The nests are small depressions made in the sand, called scrapes. Clutches usually have one to three eggs, but two eggs per nest is the average. These eggs are small, less then 1.5 inches long and about 1 inch wide. They are lightly colored with darker spots and scrawls that help them blend in with the sand and shell underneath. The incubation period for these birds is around 19-25 days, so starting on the 25th of May, we increased our survey efforts to every day hoping to catch a glimpse of the colony’s first chick.
On May 28th we arrived at the site at 10:00 a.m. which is a little later than we usually start. It was hot out, so the adult terns were sitting snug on their nests, protecting them from the direct heat of the sun. In order to get the most accurate count we move systematically across the colony from one side to the other, counting all incubating and non-incubating birds. Just as we were counting, one tern shifted in its nest, stood up, and the small head of a chick poked out from underneath! The colony’s first chick! Just four days later that number grew to nine chicks, with many more nests containing eggs that will hatch in the coming weeks. These small chicks are semi-precocial which means they hatch with eyes open, covered in downy feathers, and are capable of walking soon after hatching! Although they are mobile, they rely on their parents for food and for protection from the sun and predators. The terns primary form of defense for their colony, as our coastal biologists know all too well, is diving at and pooping on the threat! That means getting too close to the colony for a count can be messy. The parents will continue to protect and feed their chicks until they begin to fledge, at about 20 days old.
Least terns are not the only shorebirds nesting in the area… Just outside the colony, a nest containing four killdeer eggs was located during a survey! This nest was also checked each time we surveyed the area. On May 29th, the four eggs were gone and four killdeer chicks were in their place! Unlike least terns, killdeer chicks will leave the nest soon after hatching and catch their own food, but the parents are always nearby to keep a protective eye on them. Those four chicks were joined by three more from a nearby clutch, and as of June 3rd seven killdeer chicks and three adults were all foraging just south of the least tern colony.