British Columbia wetlands are proving to be just what a little amphibian needs to help increase its odds of survival.

At a new reintroduction site near Kimberley for conservation translocations:

• frogs were 20% larger and 114% heavier compared to previous release sites in B.C.
• frogs had 16.9% survival rate from tadpole to young-of-year frogs, compared to the typical three to six per cent for other true frogs.

“In our final surveys of 2022, tadpoles showed early signs of success, with young-of-year already reaching the size that you would expect from a two-year-old northern leopard frog,” said Rebecca Stanton, Interim Conservation Research Population Ecologist with the Wilder Institute.

“This is exciting news since overwinter survival is a challenge for this endangered species. We’re cautiously optimistic that this could mean wild breeding for the frogs that we released.”

Once widespread, the northern leopard frog is down to one population in B.C., likely due to habitat loss, invasive species, and disease.

The Rocky Mountain population is listed as Endangered federally and Critically Imperilled in B.C. As part of the B.C. Northern Leopard Frog Recovery Team, the Wilder Institute is using conservation translocations to prevent the local extinction of this species by reintroducing these frogs to parts of their historical range.

What makes the new reintroduction site suitable for frog habitat?

Healthy waterbodies that do not freeze to the bottom are key for surviving winter. As temperatures drop, northern leopard frogs enter a state called ‘brumation,’ where their activity slows, and their need for food and oxygen is reduced until the warm weather returns.

Frogs are sluggish during brumation, making them vulnerable to predators and disease. Northern leopard frogs typically see a 10% overwinter survival rate in their first year.

To set the frogs up for success while they endure the colder months, a new reintroduction site was selected near Kimberley using an extensive criterion of factors for determining suitable habitat, such as breeding, foraging, overwintering habitat requirements and connectivity.

The reintroduction took place on the Nature Conservancy of Canada’s Cherry Meadows Conservation Area and the neighbouring Sparrowhawk Farm wetland complex. These properties feature a creek with ideal temperature and dissolved oxygen levels, and already provide habitat for Columbia spotted frogs, all positive indicators for good overwintering habitat.

This summer, researchers will visit Cherry Meadows and Sparrowhawk Farm to see how many frogs survived over winter. Signs of overwinter survival and breeding in the wild may mean the beginning of establishing a second population of northern leopard frogs in B.C.

Lead image: A newly released northern leopard frog at the new reintroduction site. Photo courtesy Wilder Institute

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