The most interesting sounds at the Greater Vancouver Zoo don’t always come from the lions.
Inside a series of low, water-filled tanks tucked behind the public exhibits, a quieter effort is underway, one that has taken decades to refine and is now producing thousands of endangered amphibians each year.
If you listen close enough, you can hear a sound similar to a soft knocking, a mating call of the Oregon spotted frog, a species once thought to have disappeared from Canada entirely, explained Andrea Gielens, lead biologist for B.C. programs with Wildlife Preservation Canada.
“The project started when the species was emergency red listed as endangered in Canada,” said Gielens. “It was thought that the species was no longer found in Canada, and it was rediscovered.”
That rediscovery in the 1990s marked the beginning of a long-term conservation effort that now relies in part on breeding and rearing frogs at the zoo in Aldergrove.
Early on, the focus was “head starting” frogs – collecting eggs from the wild, raising them in controlled environments, and releasing them once they were more likely to survive.
But breeding the frogs in captivity proved far more complex.
“It took actually quite a long time to figure out how to breed them successfully,” Gielens said.
Success finally came in 2021. Since then, output has increased dramatically, from roughly 1,500 tadpoles a year to more than 25,000.
That milestone wasn’t the result of a single breakthrough, but a careful understanding of the frogs’ natural rhythms.
“Experiencing the seasons triggers their breeding cycles,” she said. “It’s nice in that way that we can keep them outside, and we don’t really have to manipulate their environment so much.”
Because the frogs are native to the Pacific Northwest, including B.C., Washington and Oregon, they respond well to local conditions.
Still, subtle adjustments make a difference.
Males and females are kept apart until breeding season, then introduced to improve fertilization rates. Water levels are lowered to mimic the shallow, temporary pools where eggs are laid in the wild. One female usually lays anywhere from 300 to 800 eggs per breeding season.
As Gielens reached into one of the tanks, she said, “In frogs, they will grab onto anything that moves,” gently separating two males locked together in a breeding hold known as amplexus.
Eggs, once laid, are removed from the main tanks to prevent damage and are monitored separately. Each appears as a clear, jelly-like sphere with a dark centre – the developing embryo.
Gielens said frogs are often overlooked in conservation circles, despite being one of the first ways people interact with wildlife.
“They’re thought of as these slimy little creatures, and they are,” she said. “But they’re often people’s first kind of interaction that they can get close to wildlife.”
At the other end of the zoo, Western painted turtles — an endangered species along Canada’s Pacific coast — bask beneath rows of calibrated heat lamps in a warm, carefully controlled lab.
About 200 to 300 turtles stretch out on foam platforms and plastic plants, angling their shells toward the light to absorb warmth. The artificial setup is intentional.
Real plants would be quickly torn apart, clouding the water and making the tanks harder to maintain.
Gielens said the lighting system mimics the conditions turtles rely on in the wild, allowing them to regulate their body temperature.
The work here is focused on survival. Staff collect eggs from vulnerable nests in the wild and bring them into the facility for incubation. During breeding season, there could be about 800 turtles at the facility.
Once hatched, the turtles are raised until they reach about 30 grams. This size that gives them a stronger chance of surviving predators. They are then released back into their natural habitat.
On one side of the room are the smallest turtles. Gielens ensures that the delayed growth spurt doesn’t mean there’s anything wrong with them.
“They actually have a lot of attitude for a little creature.”
Even though Gielens began her career hoping to work with big cats, she told the Aldergrove Star, while walking past the zoo’s lions, snow leopard, and jaguar, she took the leap to work alongside the smaller creatures.
“I went after how I can help, what I find my skill sets are, and how I can be useful for a species –— whether it is a bear or a frog or whatever.”
People can support Wildlife Preservation Canada through online donations at wildlifepreservation.ca/donate, choosing which project they would like their funds to benefit.