A retired research scientist is shedding some light on why Lambton County hasn't seen its usual large flock of tundra swans ahead of March break, and how mild winters may be impacting their migration habits.
Tundra swans typically rest and feed in Lambton Shores, near the end of winter, during their northward trip from the U.S. east coast to their breeding grounds in the Canadian Arctic.
Last year, thousands of swans landed at Thedford Bog early, in late February.
This year, small groups ranging from 100 to 1,000 were spotted throughout February and early March, according to Lambton County Museum's migration calendar.
As specified on the museum's website, in a good year, there may be 15,000 birds resting on the bog, as they're attracted by the wet conditions created by the snow melt.
Retired research scientist and president of the Ontario Field Ornithologists Jeff Skevington said this "odd winter" included warm spells and drier than normal conditions which resulted in some birds migrating earlier than usual. Sightings were reported as early as January 31 in Lambton County and Huron County.
"That's really early for your area," said Skevington.
"They're in smaller groups and spread out more widely looking for available places to stop. They need wet fields to linger in and then they'll feed on spilled grain in the fields as well. So that's why you don't have as many as you sometimes do. They're just more spread out this year, it's not like there are fewer this year."
Although the travel period began earlier than normal for some, Skevington said they don't appear to be further north, but in "a wide swath".
"They're in a line basically across mid-Wisconsin, U.S., [around] the middle of the northern peninsula of Michigan, U.S., and the Carolinian zone — essentially — of Ontario, as far north as a little bit north of Toronto," he said.
Skevington said based on reported sightings, the furthest north tundra swans have flown to so far this year is around Sault Ste. Marie.
However, some are scattered in areas such as Ottawa, which Skevington said is uncommon.
"This year we have more than usual. There is one flock of 20 which is unprecedented," he said. "So these birds really are wandering more widely than in a typical year as they're looking for available habitat."
Could these scattered migration habits become a trend?
"Yeah, definitely," said Skevington. "Our winters are getting lighter … we're getting a lot more melts through the winter and the snow's disappearing earlier in an average year now. Although we could still have snowy years — because this is a long-term trend it'll vary up and down, it's likely this is part of an ongoing trend."
Skevington said there are different ways birds are tracked aside from reported sightings, which include bands or Motus tags. He said the tags give off a radio frequency that can ping off of Motus towers across North and South America.
"It's a lot better than a bird band in the sense that you get these passive observations from the towers," he said.
However, he recommends using a site called ebird.org to track the large movements of birds.
In the meantime, the Lambton Heritage Museum in Grand Bend has a tundra swan exhibit that's available until April 6.
The museum hopes this week's warm weather will attract more swans to the area as a group of a thousand or more were spotted in a flooded field at the corner of Blain Road and Haig Line on Tuesday.