Overwintering success for Northern Leopard Frog project

Submitted by Lea Randall, Calgary Zoo Conservation Research Population Ecologist

Reintroducing Northern Leopard Frogs to the Columbia Marshes is funded in part by the Columbia Valley Local Conservation Fund to re‐establish self‐sustaining populations of northern leopard frogs in the Columbia marshes

Once widespread, northern leopard frogs began to decline five decades ago, likely as a result of habitat loss and degradation, invasive species and disease. Prior to these declines, northern leopard frogs were found in many wetlands in southeastern British Columbia and the Okanagan. ​Due to their declining abundance and distribution, the Rocky Mountain population is designated as Endangered. A single remaining native population exists within the Creston Valley, but this population is vulnerable to extinction. ​Northern leopard frogs play an important role transferring nutrients between terrestrial and aquatic ecosystems. They are also an indicator species, reflecting the health of the wetland ecosystems where they live.

The Calgary Zoo is part of the BC Northern Leopard Frog Recovery team, which uses conservation translocations to recover the species and prevent local extinction within the province. Our goal is to help prevent the local extinction and aid the recovery of northern leopard frogs in BC by reintroducing northern leopard frogs to parts of their range where they have disappeared.

This year, Calgary Zoo researchers assisted with breeding surveys to locate egg masses in the Creston Valley. Finding egg masses attached to submerged vegetation in the swamp can be a real challenge and requires a coordinated search effort. The team assisted with wild-to-wild translocations of northern leopard frog eggs from the population in Creston to the reintroduced population in the Columbia Marshes. To preserve the genetic diversity and integrity of the Creston population, the team only takes portions of the egg masses and only when enough egg masses have been found.

Portions of egg masses were also brought to the Calgary Zoo, some of which were released as tadpoles at the Columbia Marshes, using a conservation technique called head-starting. Head-starting involves bringing an animal into captivity during the period of life when they are most vulnerable and releasing them when they have a higher chance of survival in the wild. The remainder of the eggs will be raised to adulthood and contribute to our conservation breeding program.

We monitor the success of these reintroduction efforts using a combination of breeding call and visual surveys. This spring, our researchers observed at least one adult northern leopard frog that had overwintered at the release site in the Columbia Marshes. This is exciting news, since overwinter survival is a challenge for this species. Northern leopard frogs aren’t freeze tolerant and they only hibernate in water bodies that don’t freeze to the bottom during the winter. This observation confirmed that there is suitable overwintering habitat nearby. Recently, we have begun observing young froglets emerging at the reintroduction site indicating that metamorphosis is underway!

The Kootenay Conservation Program (KCP) in partnership with the Regional District of East Kootenay (RDEK) provide funding for projects that benefit conservation in the area from Spillimacheen to Canal Flats through the Columbia Valley Local Conservation Fund (CVLCF). The purpose of the CVLCF is to provide local financial support for important projects that will contribute to the conservation of our valuable natural areas; one step towards restoring and preserving a healthy environment.