The Greater Vancouver Zoo released 325 critically endangered frogs back into the Agassiz wilderness earlier this month to help boost the species' declining numbers.
The Oregon spotted frog, named for its distribution of black blotches with light centres on its head and back, is the most endangered amphibian in Canada.
This is the third year the Oregon Spotted Recovery team, a group of biologists and researchers, has released a batch of frogs raised in captivity to the Chaplin site in Agassiz.
"Our hopes with releasing such large numbers several years in a row to the same site would be to see our first egg masses return next year in this area," states a zoo press release.
The zoo facilitates a "head-start" program, which involves removing eggs masses from the wild and then raising the frogs in a captive environment until they are ready to be released. The amphibians usually remain in zoo care for six months.
Embryos and tadpoles in the "head-start" program have proven to have a much higher
survival rate than those born in the wild.
"We know from mark recapture that our release individuals are turning up in significant numbers in comparison to wild animals, so we know that our frogs are surviving to breeding age," said Jody Henderson, Greater Vancouver Zoo general manager, via email. "I believe we have seen individuals more than eight years old from the captive head-starting program."
The Oregon spotted frog population has seen massive declines due to an introduction of bullfrogs, green frogs and predatory fish to the area, resulting in increased competition for food and habitat.
Residing mainly in calm, shallow waters like flood plains and wetlands, the frog has also experienced a loss of breeding habitat due to activities like dam construction, excessive livestock grazing and agricultural use of water.
The Oregon Spotted Recovery team has been working to save the species since 1999, when the frog was first designated as endangered by Endangered Wildlife in Canada.
"We are extremely pleased to be involved with a great conservation program for a frog that is critically endangered and needs so much help," Henderson said.
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