Wildfire smoke drifting in from the U.S. disrupted Vancouver Island songbird migration because they rely on sight to find their way, according to a local expert.
Local birdwatchers observed an abrupt pause in normal bird activity, such as singing and feeding in the open during the smoky period, according to Guy Monty, a biologist, wildlife consultant and avid birdwatcher.
“We saw a severe drop in temperature, which limits insect reproduction — that’s their main food when they migrate. They have to conserve energy because it takes more energy when it’s colder and it was unseasonably cold during the height of the smoke,” said Monty.
The drop in activity came at time of year typically full of bird activity. Resident species are preparing for winter and migratory birds are well into their fall journey to warmer climates.
Birds are more susceptible to toxins in the air because of their biology, according to Lynne Brookes, spokesperson for Arrowsmith Naturalists, a local environmental stewardship group.
“Birds have a whole different breathing system than we do — it’s an extremely efficient one,” she said. “Because they fly, they need a tremendous amount of oxygen to burn fuel to power up their muscles and they bring in air, but it goes throughout their body in different air sacs.”
The toxic air passes through many parts of their body before being exhaled — impacting them much more than a person outside in the smoke, said Brookes.
“They are so small — it doesn’t take a lot of parts per million to start affecting them,” she said. She added the fall migration is the first for many young birds who hatched earlier this year and the smoke makes an already stressful time even more dangerous.
Monty said the smoky conditions drove record numbers of some species to the French Creek area, where the air and temperature were more hospitable.
“I have never in 25 years seen the number of savannah sparrows in Sept. that I saw this year,” he said.
When the smoke cleared, not all the bird activity returned to normal, according to Monty.
“I’m not sure if we had birds die off or they have switched to some other food source, but it’s being widely reported. I’ve noticed it myself that it’s kind of night and day at the feeders,” he said.
The wildfire smoke was just the latest threat to many bird species, whose numbers have been declining for decades, said Monty.
“At the absolute best case scenario, we’ve lost 25 per cent of all songbirds in the last 50 years,” he said.
Bird populations on Vancouver Island are collapsing due to habitat loss caused by forestry practices and residential development. Climate change has also directly led to increased bird mortality, according to Monty.
“We are seeing birds arriving [from migration] so early that they starve to death. We are seeing birds arriving at and nesting at times when the young [cannot] survive,” he said.
Between a quarter and half a million seabirds known as Cassin’s Auklet washed up dead along the West Coast over two years, he said. The birds starved when the krill population they feed on died out due to rising ocean temperatures, according to Monty.
“We’re talking about probably over 50 per cent of the population dying in a few winters,” he said.
Species such as common nighthawks, swallows and Rufus hummingbirds are also in danger of disappearing from Vancouver Island, said Monty.
The wildfire smoke may not have killed a lot of birds outright on the island, but could have serious long-term effects, according to Brookes.
“If you think about how we’ve been asking people to stay inside, especially the young and especially the elderly — well the birds have no choice,” she said.