Least Terns: fickle and feisty

by: Virginia Andrews

A perfect summer day, with blue sky and bluer ocean, sun-sparkles glinting off the waves. The white sands are hot, but the breeze is cooling. Small white birds wheel over one particular spot above the water, not too far out.Their excited, high-pitched calls announce their presence, even to a drowsy beach-goer. The birds hover and dart, like an animated Escher print above the waves. Individually they leave the syncopated mass of the flock and plunge down, into the water below. Each splashdown sends up flakes of light. A tiny bird rises up, a flash of silver in its yellow bill, dripping water. Feisty, fickle and occasionally furious, they are Least Terns: a sign of fish below.

Why Least? Least what? Least is just birder lingo for small. Of the 16 species of terns in North America, they are the smallest. About nine inches long, from bill-tip to tail-end, their wings are long and narrow. Fully extended, their wingspan is about 20 inches. They are graceful, agile fliers, sometimes called “sea swallows” for their delicacy and buoyancy in the air.

But for a little bird, they can have a big impact. They are nothing if not feisty, as any creature wandering unawares into a colony soon discovers. When a Least Tern’s nest is threatened, the parent on guard will dive-bomb any intruder. And it’s not just a liquid payload. Their rapiersharp bills can draw blood, and when it comes to protecting their young, they have no fear of engagement.

It doesn’t matter if the intruder is a gull or a researcher, a hawk or a stockbroker, they will rise to the attack. Screaming with rage, their alarm call is vociferous. In 1832, Alexander Wilson compared it to “the squealing of young pigs.” Older Nantucketers, remembering when the term “island car” meant something far less luxurious than today’s beach vehicle, might compare it to the shriek of brakes just about to give up the ghost.

Researchers working with terns have learned that just wearing a hat is not enough. Some have adopted propeller-topped beanies as terns tend to attack the highest point.

Looking silly is usually preferable to a perforated hat or a head-wound. This feisty attitude, as well as the way terns plunge in after fish, earned them another common name: “the little striker.”

They are quintessential beach birds, nesting on flat areas of sand or gravel. After wintering in the Caribbean or islands off the coast of South America, they arrive early, seeking out wide expanses of beach, looking for flat areas above the summer wrack lines. Even so, a late-season nor’easter or storm surge can wipe out a colony. So, they are also notoriously fickle, setting down and making scrapes only to change their minds and relocate.

Whatever clue tips them off that an area might not be safe, they tend to err on the side of caution. There might be good reason for that.

Least Terns used to be a regular feature of beaches all across North America, east, west and along interior rivers. Once upon a time, their colonies were not only widespread, but the birds were very abundant. A colony could contain hundreds or even thousands of birds. But all that changed in the latter part of the 19th century.

In those days, everyone wore a hat. Hats were high-fashion, status-conveying items, and women in particular had to demonstrate their family or husband’s wealth through sartorial display. Once feathers were added, there was no turning back. Soon whole birds were stuffed and worked into ever-more-elaborate chapeaux.

Feathers have exerted a primal decorative appeal across cultures through the millennia. But with the improved technology of firearms, as well as faster transportation, the ability to collect massive numbers of birds changed radically. Combined with rising incomes, the market expanded, feeding on itself as well as the natural world. Although the plume trade was at fault for much of the slaughter, private natural-history collections were also all the rage. Every boy wanted a collection of eggs, of stuffed birds and/or mammals. Hunting was no longer purely for subsistence, but for decoration and education, as well as science. Furthermore, the culture of hunting “just for the sport of it” made every living thing fair game.

Where colonies of terns numbering in the thousands were found, they were ruthlessly collected. On islands off the Virginia coast, as many as 1,200 to 1,400 birds were harvested in a single day. For 10 or 12 cents a bird, as many as 100,000 a year were taken. This was true up and down every accessible coastal area or bit of sand where they might nest.

Through the next 30 years, observers noted the reduction from thousands, to hundreds, to dozens, to single pairs spaced out a mile apart, to complete extirpation. Only a few obscure sites kept the species from complete extinction. Finally, led in America by a couple of Boston society ladies, and supported by a few sportsmen-turned-conservationists, wild birds were protected and fashions changed.

Taxonomy – the classification of groups of organisms – is constantly being refined to ever-subtler levels. Once terns were lumped together in the genus Sterna. Just recently, mitochondrial DNA studies have shaken up the picture. Now terns are considered to be paraphyletic, and so the Least Tern has been reclassified as genus Sternula. Why is this important? It helps us understand how special they are, how unique.

Given the fervor with which they were hunted, perhaps it’s not surprising that Least Terns have never recovered to anything like their previous abundance. They are endangered or threatened across most of the United States. Over 100 years of protection have enabled them to hang on, with their total worldwide population now estimated at about 30,000 pairs.

To put this in perspective, that would be less than one year’s supply at a previous generation’s rate of consuming natural resources.

Development, pollution, disturbance and climate change all still threaten them. Nesting as they do at water’s edge, increasingly severe storms and high water menace them more than ever. It is also possible that the rapid constriction of genetic diversity, in the days when they were so savagely hunted, also stressed them as a species. For these reasons, they are still protected. But protection of Least Terns also benefits other struggling beach-nesting birds, such as Piping Plovers and American Oystercatchers. Terns help define areas that require closure. This often represents efficient use of space by more than one species of birds.

A tern colony is a wonderful thing to watch, from a respectful distance. The male and female tend the eggs and the nest in rotation. When a parent calls for relief, the partner quickly arrives to shade the young from heat, or warm them from cold, while the other goes fishing. Small fish, usually sand eels or silversides, are courting gifts as well as family meals.

E.H. Forbush, detailing the exchange of food at a meal among a family of four Least Terns, wrote, “where shall we look to find a lovelier picture of happy, harmonious family relations than that shown here on this desolate beach, beside the roaring surf?”

Where indeed? ///

Ginger Andrews is a native Nantucketer, artist and birder, and leads bird walks for the Maria Mitchell Association. She writes the weekly “Island Bird Sightings” column for The Inquirer and Mirror, Nantucket’s newspaper since 1821.

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