Northern Leopard Frog Reintroduction Raven River - Year 2 (2000)
Author(s)
Kris Kendell
Summary
The northern leopard frog (Rana pipiens) is designated as Threatened in the province under the Alberta Wildlife Act (Alberta Environment 1996) and is nationally listed by the Committee on the Status of Endangered Wildlife Act in Canada (COSEWIC) as a Special concern species (COSEWIC 2000). The leopard frog has exhibited population declines and is currently extirpated from much of its former range in Alberta. The historic distribution of the leopard frog in Alberta is closely associated with major river drainages tha tmay reflect optimal breeding and hibernation sites. Information on current known leopard frog populations indicate that it is largely extirpated from the cerntral parkland and has virtually vanished from the North Saskatchewan River dranage basin and is completely absent from the upper Red Deer River drainage basin. Isolated and fragmented, remanant leopard frog breeding populations in southern Alberta are vulnerable to disturbance and degradation, potentially leading to further local loss of the species. The northern leopard frog has exhibited little ability for natural dispersal back into historic parts of its range.
A management decision was made in 1998 to begin a reintroduction project for the leopard frog. The goal of the project is to re-establish the leopard frog in historically occupied habitats in the headwaters of the upper Red Deer and North Saskatchewan River drainage basins, consequently allowing natural downstream dispersal along these watersheds.
The northern leopard frog conforms to many of the requirements proposed in conservation literature for the successful translocations. In April 1999, a pilot captive rearing program was initiated at the Raven Brood Trout Station (Sustainable Resource Development) located southeast of Caroline, Alberta and in the upper Red Deer River drainage. The facility offers infrastructure, managed access, and two rearing ponds that provide a controlled environment in which leopard frogs can be reared and temporarily confined. Several release sites were chosen in the area proximal to the Raven Brood Trout Station based on historic leopard frog records and the presence of potential suitable breeding, summering and over-wintering habitat. A second year of managed captive rearing of leopard frogs was undertaken in 2000. To date, approximately 2500 juvenile leopard frogs have been captive reared and released into the wild near Caroline, Alberta. However, apart from a single observation in the spring of 2000 of a 1999 released frog, no released leopard frogs have been captured or observed since.
During the captive rearing process, water quality, growth and development of the tadpoles, natural history observations, and population numbers were recorded and monitored. Prior to release into the wild, a percentage of the captive reared juvenile leopard frogs were randomly weighed and measured. All captive reared leopard frogs were marked using a Visible Implant Elastomer (VIE) tagging system. The bio-compatible marker was located in the webbing between the toes of one of the hind feet of each young-of-the-year leopard frog, producing an unique color and foot combination. The marking technique allows for the long-term monitoring of released frogs and the evaluation of the survival success at each release site and in each year of release. The following report details the results of the 2000 captive-rearing program of the northern leopard frog reintroduction project.