“They were behaving in a way that suggested some kind of neurological disorder,” said Leighton, a retired veterinarian and wildlife health researcher. He also noticed something else. “I could see there was an awful lot of scanning going on. You could see a seagull or two picking up something dead on the beach, repeating over and over and over down the straight coastline as I saw it. I thought there must be some significant mortality.’ Leighton, an internationally renowned scholar of wildlife diseases, did not get a chance to investigate further that day, but when he returned to Bear Island on September 3, his suspicions were confirmed. “There were skeletal remains everywhere,” he said. “Often it was just wings and breast, no flesh at all, sometimes wings.” Dr. Ted Leighton is a retired veterinarian who discovered the dead seagull on Bear Island, NS (Submitted by Dr. Ted Leighton) Leighton said it’s impossible to know how many seagulls have died on the island recently because tides wash carcasses into the Annapolis Basin twice a day, but he said the number is definitely in the hundreds. Leighton believes that the highly pathogenic bird flu was responsible for the extinction. “It’s highly unlikely that it’s anything else, but of course one has to do the exact work of testing for the virus to be sure.” Bear Island is accessible by foot at low tide and is the occasional destination for hikers and climbers. The Town of Digby recently asked people to stay off the island.
An unprecedented year
Leighton collected some samples from the island, which will be sent to the Canadian Wildlife Health Cooperative (CWHC) for testing. The cooperative, which Leighton co-founded and then directed for many years, provides disease surveillance and wildlife mortality event monitoring across Canada. Dr Megan Jones, CWHC regional director for the Atlantic and assistant professor in the department of pathology and microbiology at Atlantic Veterinary College, said it had been an unprecedented year for bird flu in the Atlantic provinces and across the continent. He said normally, in the first six months of the year, the co-op’s Atlantic office does about 300 diagnostic tests on wildlife, but this year, staff did 1,400 tests during that time. The agency has experienced such high demand that it now has to prioritize some cases because it has already spent its entire diagnostic budget for the year. Most of the dead seagulls had already been swept away by the time Leighton found them. (Submitted by Dr. Ted Leighton) From January to March, about nine percent of tests were positive for highly pathogenic avian influenza, and between April and June, that number had risen to about 20 percent. “It’s a challenge because there’s really not much we can do,” Jones said. “They’re going to congregate, there’s no social distancing, so there’s not really much we can do about it other than monitor it and try to minimize transmission.” Glenn Parsons, manager of the wildlife sustainable use program at Nova Scotia’s Department of Natural Resources and Renewable Resources, said the province has received reports of dead birds in every county and has seen cases of highly pathogenic avian flu from Yarmouth to Sydney. Parsons said the virus is spread through direct contact, including through feces and fluids, so people are advised not to touch or approach sick or dead birds and to avoid feeding birds. Anyone in Nova Scotia who finds a sick or dead bird or animal should call Natural Resources at 1-800-565-2224.
H5N1 surveillance
The outbreak of highly pathogenic avian influenza, an H5N1 strain, began in Newfoundland last December with the discovery of the virus on a show farm. After that, a case appeared in a Canada goose in Nova Scotia and then in other birds in New Brunswick and Prince Edward Island. In the intervening months, the virus has spread across the continent after sweeping through Europe last year. It has caused significant mortality in wild bird populations and has been found in foxes in Nova Scotia and Prince Edward Island as well as seals in Quebec. In other parts of Canada and the U.S., it has been found in skunks, raccoons and bobcats, Jones said. When a seagull dies, other seagulls collect and eat the carcass, spreading bird flu. (Submitted by Dr. Ted Leighton) This particular H5N1 strain has not caused significant illness in humans, but public health officials are closely monitoring any outbreaks, as human transmission of the virus could trigger a global outbreak. The CWHC sends samples of all positive cases in wildlife to the National Center for Foreign Animal Diseases lab in Winnipeg, which is genetically sequencing the virus to try to pick up any mutations that might make it more likely to infect humans.
