Harsh winters, meaning those with bone chilling temperatures and serious amounts of snow, such as last year and this year, bring the same question on an almost daily basis — why do I see “sea gulls” at the mall, at fast food restaurants, and at garbage dumpsters?
The answer is weather related, but first let’s address the term “sea gull.” Everyone who has ever been to a coastal beach knows what it means, but “sea gulls” are not limited to seashores.
In fact, Franklin’s gulls nest on the prairies of the northern Great Plains. Bonaparte’s gulls nest on the edges of the boreal forest in Canada and Alaska.
And California gulls nest near lakes throughout the west.
Among ornithologists and birders, the term “gull” suffices. Most of the winter gulls seen here in the inland east are ring-billed gulls and herring gulls. Both are common along the Atlantic coast in the summer, but large populations also nest inland on the many islands of the Great Lakes.
When winters are mild, they stay near the lakes. But when polar vortices plunge southward and send us into a prolonged deep freeze, gulls wander south in search of open water.
Last year was a classic case.
In December of 2013, the Great Lakes began icing up, but in mid January, 2014, temperatures plummeted and the freeze accelerated.
By March 6, 2014 the Great Lakes were 92.2 percent covered by ice. When it gets very cold, ice-up can happen quickly.
It’s happening again this year. According to the Great Lakes Environmental Research Laboratory (GLERL), on Jan. 6, less than six percent of Lake Erie was frozen. By Feb. 9, more than 90 percent of Lake Erie and 54 percent of all the Great Lakes were frozen.
Under these conditions, smaller bodies of water near the Great Lakes also freeze. When this happens, gulls head south in search of open water.
During the day they scavenge at landfills, dumpsters, parking lots, and anywhere else they can find food. At night, they roost on ice near open water where they are relatively safe from predators.
These evening flocks can be quite impressive and often draw attention from gaggles of birders.
In Pittsburgh, for example, thousands and sometimes close to 10,000 gulls gather near the confluence of the Allegheny, Monongahela, and Ohio rivers. Most are ring-billed gulls, many are herring gulls, and sharp-eyed birders are always looking for rarities such as glaucous gulls, ivory gulls and greater black-backed gulls.
Similar gatherings occur near Buffalo and Niagara Falls.
Always rewarding. Scanning thousands of birds for one or two individuals can be tedious, but it is always rewarding. That’s what birders do. So that’s why we see gulls in winter. Ice freezes them out of preferred places, and they head south for open water.
In the spring, when the ice thaws, the gulls will return north to islands in the Great Lakes and beyond. The most frequently seen winter gulls are ring-billed gulls. They are about 18 inches long and have a four-foot wingspan.
The yellow bill is encircled by a black ring near the tip, hence its name. Other diagnostic features include a white head, yellow legs, yellow eyes, pale gray back, and white underparts.
Herring gulls, the other common winter species, resemble ring-bills, but are larger, about 25 inches long with a five-foot wingspan.
The bill is yellow and the lower bill has a red spot near the tip. Also, look for the pale gray back, white underparts, and pink legs.
In nature, gulls are opportunistic scavengers. They eat fish, carrion, crabs, insects, mollusks and almost any sort of organic garbage. Larger gulls can be quite predatory. Great black-backed gulls, for example, can swoop down and swallow ducklings and shorebird chicks whole.
If you’re puzzled seeing winter gulls, just look around. It’s probably very cold, you’re probably just a few miles from a lake or river, and there’s probably an open trash receptacle nearby.
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