Fowl play: The surprising way invasive ticks migrate thousands of kilometres
Ticks have always been stowaways, but that wasn't a problem until the climate started warming.
Spring is a busy time for birds.
Longer days trigger their physiological adaptation to prepare for migration, and in the weeks ahead, they will grace Canadian skies.
Be on the lookout for warblers, hummingbirds, and pelicans, among others. They will return to Canada after wintering in parts of the U.S., Mexico, and South America.
Unfortunately, some of those birds will bring along tiny stowaways in the form of invasive ticks, according to a November joint study.
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The ticks that latch on to migrating birds can travel thousands of kilometres, winding up in cooler climates like Canada.
Historically, that hasn't been an issue: Many tick species can't survive our harsh winters, "but now, thanks to the climate crisis, it’s getting easier for ticks to survive and spread, potentially bringing novel tick-borne pathogens with them," reads a statement by the study's authors.
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Ticks in Canada
The study says a warming climate is changing the geographic distribution of ticks.
“For some migrating exotic ticks, global warming may create conditions at their northern destination that are similar to their usual range," Dr. Lorenza Beati of Georgia Southern University, a co-author of the study, says in a statement.
"If warmer climatic conditions are combined with the presence of suitable vertebrate hosts for all tick life stages, the chance of establishment is going to increase.”
At present, there are several types of ticks found in Canada. Only black-legged ticks can transmit the bacteria Borrelia burgdorferi, which is responsible for Lyme disease, and that's only if the tick is infected with the bacteria.
Lab studies show that black-legged ticks are active anytime the temperature is above four degrees Celsius, Katie Clow, an assistant professor at Ontario Veterinary College, told The Weather Network in 2021.
Black-legged ticks prefer wooded and brushy areas and places where humidity is higher. They're most active in humid conditions when temperatures are lower.
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Ticks spread other diseases, too
Lyme disease isn't the only concern. Worldwide, there are about 899 species to ticks, which can carry a bevy of diseases, with symptoms ranging from headaches to rashes.
One tick, the Lone Star tick, carries a pathogen with an even more concerning effect.
Bites from infected Lone Star ticks can develop into alpha-gal syndrome. When they bite, the ticks transmit a sugar molecule called alpha-gal. In some, this can trigger the immune system to react and produce allergic reactions to red meat.
There's no treatment for the allergy other than avoiding red meat, but for many people, the condition goes away over time.
While not established, the Lone Star tick has been spotted in Ontario and Manitoba.
“If conditions become more hospitable for tropical tick species to establish themselves in areas where they would previously have been unsuccessful, then there is a chance they could bring new diseases with them,” Dr. Shahid Karim of the University of Southern Mississippi, lead author of the November study, says in a statement.
Additional research backs this theory: A 2022 paper from McGill University finds that an increasing number of Canadians are getting sick from tick-borne pathogens and previously rare infections are beginning to pop up.
Header image: April Walker and Cheryl Santa Maria for The Weather Network.