Nelson isn’t alone in having a lot of Canada geese as permanent residents. A Google search easily turns up dozens of stories about local governments in Canada and the US agonizing over how to deal with too many geese.
The geese are said to contaminate beaches, damage crops and sensitive ecosystems, prevent native waterfowl from nesting, and threaten aviation.
Solutions include culls as well as various measures like loud noises, vegetation management, and interfering with hatching. There appears to be no concrete evidence that any of these methods work over the long term.
Nelson’s Canada geese grabbed everyone’s attention in recent weeks because they were suspected of creating the high E. coli levels in the water at Lakeside Park.
A very high reading of 4,820 units per 100 ml of water taken on August 10 was later discounted by the city as a lab error but in the preceding three weeks there were levels of 1,100 and 845 recorded. The acceptable level is 200. The most recent reading, taken last week, showed a level of 75 and prompted the removal of danger signs at the beach.
Escherichia coli, usually called E. coli, refers to a large group of bacteria that is commonly found in the intestines of humans and animals.
The city’s public works director Colin Innes said at the time that he did not know that geese caused the high levels, and he said a search for a sewage leak in Nelson turned up nothing.
Dr. Thomas Edge says it’s very difficult to tell for sure if E. coli at a beach is caused by geese or not.
Edge (pictured below) is a research scientist at the federal Ministry of Environment and Climate Change. He conducts research on water-borne pathogens and microbial source tracing techniques. His work has been mostly concentrated on pollution of the Great Lakes.
The the risks associated with goose or seagull droppings still need more study, he told the Star. And he says E. coli from goose feces is not as dangerous as from human or cow feces.
“But the risks are not zero, and as we see more opportunities for geese and people to come into contact, there will be more research going on.
“E. Coli can come from a variety of types of fecal pollution sources,” he said. “So if you get a high count of E. coli you know you have fecal contamination but you don’t have a way to say that it is a human or goose E. coli.”
Edge says the standard tests also don’t show whether the E. coli contains safe or dangerous strains of E. coli.
“Most are harmless E. coli that we all carry around in our guts, and animals do too, but there are strains of E. coli like the 0157:H7 strain that can make people sick. They are generally rare but they require different methods to detect if hey are in a water sample or not.”
Those methods, only available to research facilities and not available to the Nelson public works department, are known as microbial tracking. They use DNA analysis to identify the contamination source.
“We collect thousands of E. coli isolates, and we also get the E. coli isolates from seagull, goose, dog and cat droppings and sewage effluent, and we look at all those and get DNA fingerprints.”
These methods, Edge said, are time consuming and expensive. And they very localized, and because the DNA fingerprints change a lot, it only works for a short time.
“There are companies starting to use these tools but they not common yet,” Edge said.
He said the problem with E. coli in water is that swimmers will tend to ingest it. But there is potential danger for children playing along the shore, too, because “geese usually drop droppings on the sand along the waterline, so the sand can serve as a reservoir, and that is where kids typically play, and sometimes they eat sand.”
Edge said he is not aware of any outbreak of disease that clearly happened because of geese.