Turkey vultures from Cowichan Valley tracked almost to Guatemala
‘This hasn’t been done before in this area,’ UVic researcher says
The Cowichan Valley is playing a central role in a unique BC research study into the migratory patterns of turkey vultures.
Nine vultures — six adults and three juveniles — have been live-captured in the Cowichan Valley and fitted with solar-powered transmitters. The data is captured via satellite, and downloaded when the birds are within cell-tower range.
Last winter, the nine vultures were tracked as far as southern Mexico, near the Guatemalan border. All arrived back in the Cowichan Valley this spring, or are on their way.
“This is the first study tracking them in the wild and looking at their local ecology,” says Cara Herrington, a graduate student in biology at the University of Victoria, who is working in partnership with Gillian Radcliffe of The Raptors. “This hasn’t been done before in this area.”
The goal is to put transmitters on at least 14 birds. The vultures are lured in with meat such as chicken or turkey, then caught in remotely triggered nets. “They’re tricky to catch, very cautious,” she says.
Of special interest is the fall migration, when the vultures must fly more than 20 kilometres across Juan de Fuca Strait.
They “kettle” in the sky in large numbers near East Sooke Regional Park, southwest of Victoria, before heading south. “The theory is they’re waiting for ideal weather conditions,” Herrington says.
Last fall, eight of the vultures crossed as expected, but one flew back to Saltspring Island (where it had spent most of the summer), then island-hopped southward to Washington state’s Puget Sound.
The transmitters are set to provide data every 30 minutes.
That changes to every every two minutes over the strait.
Herrington hopes to match the tracking information with weather data to determine what specific conditions the vultures require to cross the strait. She’d also like to know how climate change might impact the vultures’ crossing.
Some vultures don’t migrate at all. They spend the winter on Vancouver Island either by choice or perhaps because they missed the weather window to head south.
The study will also look at the behavioural differences between breeding and non-breeding birds, including sizes of home ranges.
The transmitters weigh less than three per cent of the birds’ body weight, and are designed to transmit data for their entires lives.
“We want to make sure the birds and the project are successful,” Herrington says.
Turkey vultures have expanded their range in BC in recent decades, perhaps benefitting from global warming. Locally, they nest in rocky bluffs, and the young fledge later in summer.
Read more about turkey vultures in Hakai Magazine: https://hakaimagazine.com/features/the-vulture-watcher/
(sixmountains.ca photo of turkey vulture at Cowichan Bay; Cara Herrington/Gillian Radcliffe nest-cam photos of adults and young at nest sites; Radcliffe photo of Herrington fitting transmitter to vulture’s back.)
Subscribe free to sixmountains.ca. More than 47,000 unique visitors.
— Larry Pynn, April 20, 2024
