American Bullfrog

The American Bullfrog (Rana catesbeiana) or "bullfrog" is a large green or brown amphibian native to eastern North America. Bullfrogs were introduced to the Pacific Northwest approximately 80 years ago for the frog farming industry. When frog farming was abandoned the remaining frogs were released into the wild. Bullfrogs can be found throughout the Lower Mainland, Fraser Valley, Sunshine Coast, and east coast of Vancouver Island. South western British Columbia is the northern limit of their range. Bullfrogs are mostly aquatic, preferring shallow, warm ponds and lakes. They can be found in ditches, slow streams and backyard ponds. Native frogs such as the Red-legged frog and Pacific Treefrog may be found in both aquatic and terrestrial habitat such as dense forests.

In Delta, a network of creeks, sloughs, ditches and ponds stretch across the landscape providing habitat for a range of amphibians. Thorough amphibian studies were conducted in Delta in the early 1990's and records of bullfrog presence exist in almost every Delta watershed, including Burns Bog. Creeks, ditches and backyard ponds plus people have moved bullfrogs around and facilitated their spread and establishment locally.

Potential impacts posed by bullfrogs to native flora and fauna concern predation and competition for space and food. Great Blue Herons, of which the largest population occurs in the Fraser River Delta, and other species like osprey, kingfishers, snakes and raccoons prey on bullfrog tadpoles, froglets and smaller adult frogs. Bullfrog populations are also controlled by cannibalism.

In the Burns Bog Ecological Conservancy Area Management Plan (Plan), adopted by Delta, bullfrogs are identified as one of the five non-indigenous animal species reported in the Bog. The Plan includes monitoring areas for invasive species presence and abundance as bog restoration proceeds and to develop management strategies for their control as required. This is classified as a "medium priority action" with a time frame for implementation given as 6 to 15 years.

For more information, please check out the Provincial and Federal sponsored "Frogwatch Program" www.env.gov.bc.ca/wld/frogwatch and http://www.frogwatch.ca/.