Herring Gull (Photos by Don Reimer)
Herring Gull (Photos by Don Reimer)
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In my previous column, I wrote about the prospects of seeing flocks of northern finches around Maine this winter. Since finches are such colorful and active beings that bring beauty and definite excitement to our yards, they become ready favorites with many bird watchers. But other types of interesting birds also visit our coastline during the winter season. In particular, I’m thinking about gulls that wander south from Canada and beyond.

Gulls, you say? Well yes, like the finch irruptions, certain species of gulls tend to arrive in periodic winter cycles. But why don’t these gulls appear in consecutive years? The probable answers lie in a successful summer nesting season and the subsequent increased competition for winter food resources.

Our most common coastal gulls are the familiar gray-backed Herring Gulls, found in coves and harbors. These are “4-year gulls” that do not attain full adult plumage until 4 years of age. They begin as brownish juveniles with dark eyes and bills, and their plumage characteristics and bill and eye color undergo gradual changes throughout the four-year span. These predictable changes make it possible to age gulls through their progressive phases.

Great Black-Backed Gulls, the world’s largest gull species, are the other gull we see routinely in Maine. Both gull populations have dipped in recent decades due to declines in the commercial fishing industry and the closure of open dumps.

We could see two forms of “white-winged” gulls this winter — the Iceland and larger Glaucous Gull that hail from Arctic areas. Unlike typical gulls with black wingtips, these birds have white translucent wingtips. The immature and sub-adult birds are generally whitish overall, making them stand out from others. These are both “4-year gulls” whose appearance will transition with time.

Ring-Billed Gulls are “three-year” gulls that over-winter in small numbers near the coastline. Named for the black band encircling the bill, these medium-size gulls are often seen in city parking lots and around fast-food restaurants. It is noteworthy that traces of trans-fat deposits are found in the bloodstreams of gulls that share in our human diets. My personal experience with a leg-banded Canadian Ring-Billed (F2Z) now extends into the sixth winter he has spent in Rockland. Last May he was spotted at his island nesting colony of 45,000 pairs near Montreal.

Bonaparte’s Gulls and Black-Headed Gulls are smallish “two-year” gulls that are somewhat similar in appearance. In flight, these gulls are most distinguishable by a flashing wedge of white feathers in the fore-wing. This key identification feature is highly visible from considerable distances. Consult a field guide for further ID characteristics. The Bonaparte’s Gull was named after Napoleon Bonaparte’s nephew Charles, an early and famous ornithologist who spent time in America. Black-Headed Gulls are colonizers from Europe that breed in limited numbers on Newfoundland. My accompanying photo depicts the maroon-red bill and winter plumage of an adult individual (no dark hood in winter). A gorgeous specimen indeed!

Why study gulls? A better question is why not? They are large-bodied birds that offer convenient and extended looks. Check out sites along the Rockland waterfront where gulls congregate around docks or loaf in the harbor. Port Clyde’s Marshall Point Lighthouse is another favorable spot to observe gulls in flight or in the water. If you study them carefully, you may observe some fascinating details of their lives. For example, you might observe droplets of water dripping from their nostrils. Did these birds somehow develop a winter head cold? No, the gull’s salt glands are simply excreting excess salt from its system. After all, unlike us humans, gulls can safely drink seawater.