Translocation of Northern Leopard Frogs (Rana pipiens) in the Upper Red Deer River Drainage Basin


Kris Kendell


The Northern Leopard Frog (Rana pipiens) has exhibited population declines in the province of Alberta and is currently extirpated from much of its former range. Remnant populations of leopard frogs in Alberta have demonstrated limited recolonization potential, and are therefore vulnerable to disturbance, leading to potential further local extirpations. In the spring of 1998 a management project was proposed to repatriate the Northern Leopard Frog into currently vacant areas of its historic range. The primary objective of this project was to establish breeding populations of Northern Leopard Frogs in formerly occupied habitats in the headwaters of the Upper Red Deer and North Saskatchewan River drainage basins. In order to help ensure the success of the project, research on fall natural history and required overwintering conditions critical to hibernating leopard frogs was continued in the field. 

In September 1999 a comprehensive study investigating winter physiology and ecological requirements of the Northern Leopard Frog took place in the area surrounding the Raven Brood Trout Station near Caroline, Alberta. The study involved the tracking of 16 translocated adult leopard frogs to potential overwintering locations along Beaver Creek and the Raven River, using radiotelemetry. Aquatic parameters relating to overwintering leopard frog requirements were measured and recorded throughout the study area in suitable overwintering habitats. Additional habitat characteristics (aquatic and terrestrial) along Beaver Creek and the Raven River were recorded at each radioed frog observation during the radio-tracking period. This included a physical habitat description of both the creek and upland, and water quality tests in the immediate area of the frog observations. Microhabitat selection and frog activity were also noted upon each observation during radio tracking, generating a wealth of ecological and natural history information relating to the fall activities of the translocated leopard frogs in this study. 

Sixteen translocated leopard frogs were collected from southern Alberta and were released into Beaver Creek, near the Raven Brood Trout Station, near Caroline, Alberta. Initially, 8 of the translocated leopard frogs were released on 28 September 1999 into sections of Beaver Creek. Eight additional translocated leopard frogs were released into sections of Beaver Creek on 29 October 1999. Radiotelemetry of the leopard frogs began on 29 September 1999 and was concluded on 17 April 2000. The eight translocated leopard frogs, of the first release, travelled combined total distance of 1165 meters during the tracking period. The remaining eight translocated leopard frogs, of the second release, travelled a combined total distance of 740 meters during the tracking period. With the exception of two separate individual frogs, all frogs remained witin 1 m of the water's edge of Beaver Creek, with suubstantial movements occurring in a downstream direction. Three of the 16 leopard frogs released during the course of this study appeared to have successfully survived to, and the initiated hibernation. Two of these three leopard frogs were subequentially found deceased (causes of death unknown) and one was determined to be in winter dormancy as on 22 December 1999. Extensive searches for the last surviving frog in a section of the Raven River between 17 April and 01 May 1999 produced no observations or specimen. Of the remaining 13 translocated frogs three shed their transmitter, four were depredated, two demonstrated indications of disease and subsequentially died (actual cause of death unknown), one experienced a transmitter malfunction, two were discovered frozen (one in water and one on land), and one was discovered deceased (cause of death unknown). All deceased frogs collected were sent to the Canadian Co-operative Wildlife Health Center, Saskatoon, Saskatchewan for examination and necropsy. 

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