|1/30/2013 11:10:00 AM|
A Trio of Winter Gulls -
by Don ReimerGulls are some of the most highly mobile of birds, often shifting their regional locations with the seasons. As we might expect, there is a general southbound parade of gulls during the winter months. And while a few adult individuals arrive here in mid-winter when food grows scarce farther north, a larger share of our winter visitors are immature gulls. As with most families of birds, often there is a handful of over-achievers that push the migratory envelope.
Since gulls are quite approachable and easily viewed, we can learn a lot by observing their plumage characteristics, improving field identification skills that translate to other sets of birds. Immature gulls, in particular, show distinctively marked feather patterns that highlight certain topographical features such as wingbars and tailbands. The bare parts, such as bills, legs and eye color, are also worth noting.
Recently I photographed three species of northern gulls at Owls Head Harbor. The two smaller species, a "first-winter" Black-Headed Gull and an adult Bonaparte's, are labeled as "hooded gulls." Both species have blackish (actually brownish) heads in adult summer plumage; in winter, a smudgy crown and black dot behind the eye is all that remains of the dark head pattern. These are both "two-year" gulls, meaning that it takes two years for them to attain their full adult plumage.
Both species have a flashy white leading edge to the wings that is very evident in flight. The Black-Headed Gull is slightly larger and has a dark underwing and a crimson red bill and legs. The daintier Bonaparte's, named for Napoleon Bonaparte's nephew Charles, has a thin black bill and a small dove-like head.
The Black-Headed Gull breeds across much of Europe and Asia and also in coastal eastern Canada. Being an opportunistic feeder, it eats insects, fish, seeds, worms, scraps and carrion. This is a noisy species that nests in colonies. It is not a true pelagic species and is rarely seen far out to sea. The eggs of the Black-Headed Gull are considered a delicacy by some in the United Kingdom and are eaten hard-boiled.
Unique in its northern breeding habitat, the Bonaparte's Gull nests in pine trees near water in boreal forest zones. With buoyant tern-like flight, it forages coastlines and open ocean during winter, preferring plankton, insects, and fish. Weighing about seven ounces, the Bonaparte's Gull is the second smallest of the North American gulls (only the rare Little Gull is smaller).
The third gull I discovered was an adult Iceland Gull, a breeder from high Arctic Canada and Greenland with white wing tips and light gray back. Many other gulls, such as Herring Gulls, show varying amounts of black feathering in the outer wing. Like most of the larger gull species, Icelands are "four-year" gulls. Adults have yellow eyes, deep pink legs and a red dot on the lower mandible. These gulls typically forage while flying, picking up food at or just below the water's surface, but also feed while walking or swimming. Food is usually swallowed in flight. Their scavenging habits lead them to investigate garbage dumps, sewage outlets and fishing ports.
Winter is perhaps the optimal time to spot these usual gulls around our local harbors. Gulls are an interesting part of Maine's seasonal birdscape.
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