So they began raiding farms, eating cherries off the trees and tomatoes ripening on the vine their favorite farm foods plus corn, peas, beans, and even onions. They learned to roost in trees, a first for the species. The ring bills are supremely adaptable, unlike their kin species, the herring gulls, whose numbers are declining because they stick to eating fish. The ring bills also ate small songbirds, wiped out the piping plover at Long Point on Lake Erie by raiding their nests, and elbowed aside the long-settled colonies of common and Caspian terns. The ravishing hordes then spread northward past Sudbury and New Liskeard, to northwest Lake Nipigon at the beginning of the 1990s, then even farther west to Lake of the Woods, and downstream to Quebec and the gulf.
Gulls can also cause swimmer's itch.
The gulls are natural carriers of schistosome trematodes, a parasite expelled in their excretions. After the parasite burrows into a human, it encysts and dies, leaving tiny, itchy red sores. On occasion, offices in Oshawa and Nanticoke have closed for the day fumes from gulls' defecations, sucked into air intakes, caused workers to gag. In the Great Lakes-St. In Toronto, the ring-billed gull soared from 20 nesting pairs in 1973 to 60,000 pairs today at Tommy Thompson Park.