Great Black-backed Gull, Larus marinus
By Tom Dennis
The Great Black-backed Gull is one of many gull species found in our area. This gull holds the honor of being the largest gull species, not only in our area, but in the world! They are seen locally only during the winter months when the far-northern populations migrate to areas with open water, including the lower Great Lakes. These birds are often mistakenly called “greater” black-backed gulls, an understandable mistake since we are occasionally visited by a similar species, the Lesser Black-backed Gull; go figure!
The sudden deep freeze that we are encountering this February (2021) has seemingly turned back the clock to times when we experienced very cold winters and the resulting surface freeze on nearly all local bodies of water; including the Great Lakes. Recent reports show that Lake Huron presently has over 40% of its surface, ice covered. This condition causes a large concentration of waterfowl, gulls, and even eagles on the open water of the swiftly moving (and therefore relatively ice free) northern parts of the St. Clair River. Here they can find abundant food in the form of fish, crustaceans, mollusks, insect larvae, aquatic plants, and yes, even other birds. This also makes the Blue Water Area a huge draw for birders who come great distances to see many beautiful bird species, many of which are rarely seen up close.
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These gulls (notice that I don’t call them “seagulls” as no respectable “birder” would use this common generic misnomer) are found on the Atlantic Ocean coastal regions of North America and Northern Europe with breeding zones ranging from the Carolinas to the northern maritime provinces of Canada and Greenland. The population is strong now following complete decimation in some areas during the 1800’s when their feathers were used extensively to decorate hats and other clothing. The genus name Larus is Latin for “gull” or “large sea bird” with the species name, marinus, meaning “marine”. These birds are the “bullies” of the waterfowl world and in areas devoid of Eagle species, they assume the position of top raptor as predators of birds and even medium-sized mammals.
Great Black-backed Gulls take four years to mature into their adult plumage. The sexes are identically colored and differ only in size with males weighing in at slightly over 4 pounds and females being slightly smaller. Adult birds are fairly easy to identify as they are so much larger than other gulls. They have bright white heads and underparts that contrast sharply with stark black upperparts and black wings with white tips and edges. The bill is bright yellow with a red dot on the lower mandible and they have dull pink legs that along with size differential, distinguishes them from the yellow-legged Lesser Black-backed Gull.
These birds are opportunistic, omnivorous feeders and they are highly predatory as mentioned above. They are known to chase other birds, including small ducks and other gull species, until they are exhausted and defenseless and they swallow most of their prey whole. Rabbits, rats, and even raccoons are also included in their diet and they have been seen stealing food from other birds including Peregrine Falcons and Northern Goshawks. Despite their wide variation in foods, they feed their young almost exclusively on regurgitated fish, yum!
If you have never seen one of these giant gulls (or want to see them again) just head down to the St. Clair River and look for the large black and white gulls as they hitch a ride on an ice flow. Look closely as that big bird just may be the competition, a Bald Eagle. Please visit Blue Water Audubon on Facebook for up-to-date birding news.
Tom Dennis is a free-lance writer, passionate birder, zoologist, creation scientist, and naturalist.