GULLS AND TERNS OF TEN MILE LAKE

by Carl Hertsman

For the most part, gulls and terns tend to nest in colonies on sandy beaches and sandy islands. (Exceptions include the Fairy Tern of the Pacific islands and the Bonaparte's gull which nest in trees.) Eggs of gulls and terns are the color of sand, as are the young, so that they are less visible to predators. Ring-Billed and Herring gulls are omnivorous and opportunistic feeders; their numbers have rapidly increased with the increase in human development and man-made dumping areas. These gulls will also predate on tern eggs and young, so gull colonies are crowding out the colonies of nesting terns. Increased numbers of dogs and raccoons and losses of habitat have also seriously decreased the numbers of terns in many areas. As far as I know, no gulls or terns nest on Ten Mile Lake, nor do I know whether they did so in the past. (Has anyone seen these birds nesting at the lake, now or in the past?) Further, I have not been present to witness the arrival times of these birds.

I will give brief descriptions of the mature birds; immature gulls can be difficult to identify where there are numerous species.

The Ring-Billed Gull: This is the common gull seen on TML, roosting on swimming platforms, boat awnings, etcetera. The adults are whitish with slate grey wings, the ends of which are black. There is a blackish ring near the end of the bill, hence the name. Immature members of the species are brownish in color, and slowly turn to the white of adults. Adult birds are 17.5 inches long with a wingspan of 48 inches. Gulls at TML appear to be non-nesting adults; having no parental responsibilities, they can hang around. When the dump was open, I would see them winging to the dump in the morning and returning in the evening. They are also fish eaters, and can be seen swimming on the surface of the Lake snapping up insects. Plastic owls do not deter them; they will sit on the owl. These birds are still present when we leave TML in early October. They winter primarily in the southern and coastal US, though we see them in southern Ohio.

The Herring Gull: This bird is uncommon on TML in the summer, though it is described as common in the Chippewa national forest. Birding guides show it nesting primarily in Canada. As a migrant it can be seen on TML mostly in spring and fall. The colors of the bird are similar to the Ring-Billed, but the adult Herring Gull has an orange spot on its lower bill; the young peck at this spot to stimulate the adult to regurgitate food for them. Immature birds have a black ring around the bill. This bird is much larger than the Ring-Billed, with a length of 25 inches and a wingspan of 58 inches. This size difference is very apparent when the two species are together.

The Bonaparte's Gull: This bird is named after a nephew of Napoleon Bonaparte; (the nephew was an ornithologist in the 1800's and spent several years studying birds in the US). This species winters primarily along the coasts and migrates to its nesting grounds in Canada, including the subarctic. These birds are much smaller, and have a buoyant, tern-like flight. Adults have black heads and bills; the immature birds (and winter adults) have a whitish head with a dark spot in back of the eye. In flight they are easily identified by the white window toward the end of the wing. These birds nest on the branches of coniferous trees in Canada, particularly near the northern edge of the tree line, near water. A flimsy nest is built; the young are fed in the nest until ready to leave. The summer diet is primarily insects though in the winter they eat more fish, plus insects, crustaceans, etcetera. The birds spend most of the year in their winter range. On TML they congregate in small flocks (numbers vary from year to year) starting late July and leaving in the fall. Some immature birds are present, but I suspect that some of the adults are changing to winter plumage while at TML. They feed by plunging into the water after fish, but also pick up insects both on the water and in the air. The Franklin's Gull is similar to the Bonaparte's; it is present in western Minnesota, but uncommon on TML. It does not have the white window on the wing.

The Caspian Tern: This bird, the rarest of the terns and even larger than many gulls, has a world-wide distribution both on salt and fresh water. Adult breeding birds have a black cap extending beneath the eyes and a dark red bill. Body length is 21 inches, and wingspan is 50 inches. (The slightly smaller Royal Tern is not found in Minnesota.) The Caspian is a spring and fall migrant on TML. These birds seem to like Long Bay where they may stay for awhile; I also see an occasional few birds flying south over TML in September. Range maps in bird guides show these birds as nesting in a few spots in northern Minnesota (possibly, Leech Lake); they nest on islands and shorelines. They tend to fly high and plunge into the water after fish. The call is a harsh, loud combination of croak and scream.

We used to see a few Black Terns, which are black with grey wings and lower body, but not in recent years. They are seen in western Minnesota. We also used to have some Common Terns, but the numbers have plummeted. Range maps indicate breeding mostly in Canada and a few in northern Minnesota, so it should be possible to see this bird. The Arctic Tern migrates by way of the oceans, not inland, and nests in northern Canada. Note that in the fall terns are changing into winter plumage and may not look like the summer adults; even the bills can change color.