Northern Leopard Frog Western Boreal/Prairie populations
Scientific Name: Lithobates pipiens
Other/Previous Names: Northern Leopard Frog (Prairie population)
Taxonomy Group: Amphibians
Range: Northwest Territories, Alberta, Saskatchewan, Manitoba
Last COSEWIC Assessment: April 2009
Last COSEWIC Designation: Special Concern
SARA Status: Schedule 1, Special Concern
Image of Northern Leopard Frog
The Northern Leopard Frog is green or brown, or a mixture of the two. It gets its name from the dark spots surrounded by light borders on its back and sides, which resemble leopard spots. Light-coloured ridges line its back, one on each side, from behind the eyes to the lower back. The underside is whitish and prominent. Adults are 6 to 11 cm long, and females are generally larger than males. During the breeding season, males develop dark, swollen nuptial pads on the innermost fingers. As in several other species of frogs, their front legs are longer and more powerful than those of the females. The eggs are small (1.5 mm in diameter) and velvety black on top with white undersides. Newly hatched tadpoles are slender and black, and measure only 8 mm.
Distribution and Population
The Northern Leopard Frog occurs in North America, from southeastern British Columbia to Labrador, and from the southcentral Northwest Territories down through the central and southwestern United States, near Mexico. Northern Leopard Frogs that occur in Newfoundland and Labrador, Nova Scotia, Prince Edward Island, New Brunswick, Quebec and Ontario belong to the Eastern population, whereas those found in Manitoba, Saskatchewan, Alberta and the Northwest Territories belong to the Western Boreal/Prairie populations. The Rocky Mountain population is restricted to the southeastern corner of British Columbia. In Alberta, the majority of current sites are now restricted to the southeastern portion of the province. Current distribution information for Saskatchewan is largely lacking. However, small populations are known to exist in the region north of Lake Athabasca in northeast Alberta and northwest Saskatchewan, into adjacent southerns parts of the Northwest Territories. The Northern Leopard Frog is believed to be relatively widespread in southern Manitoba. There are currently no estimates of the numbers of adult Northern Leopard Frogs in the Prairie/Western Boreal populations. Prior to the large-scale declines observed in the early 1970s, the Northern Leopard Frog was widespread throughout its range. In much of Alberta, the species has steadily declined in abundance and remaining populations are small and isolated. A general lack of information hampers appropriate assessment in Saskatchewan. In the mid 1970s the species recovered from sharp declines in Manitoba, where it is now believed to be common throughout the southern regions of the province. Populations in Manitoba are not currently monitored. There is no information on the abundance of Northern Leopard Frogs in the Northwest Territories.
The Northern Leopard Frog uses several distinct habitat types to meet its needs throughout the year. Separate sites are generally used for overwintering, breeding and foraging, and contiguity between these habitats is necessary for the species’ survival. Overwintering sites are well-oxygenated bodies of water that do not freeze to the bottom. Thus streams, creeks, rivers, spillways below dams, and deep lakes and ponds may all provide appropriate overwintering conditions. Breeding occurs in pools, ponds, marshes and lakes, and may occasionally occur in slow-moving streams and creeks. The tadpoles also use these types of streams. A typical breeding pond is 30 to 60 m in diameter and 1.5 to 2.0 m deep; it is located in an open area with abundant vegetation and no fish. In the summer, the frogs are found in a wide variety of habitats, particularly moist upland meadows and native prairie; riparian areas and ponds facilitate dispersal and provide additional corridors for movement between habitats. Northern Leopard Frogs seem to prefer areas where the vegetation is no more than 30 cm tall and is relatively close to water. Recreational subdivision in rural southwestern Alberta is increasing, and agricultural land use remains widespread throughout this and the other Prairie provinces.
The Northern Leopard Frog emerges from overwintering ponds in early spring shortly after the ice has melted, when the water temperature rises to 7 to 10°C. Adult males are the first to arrive at the breeding sites, where they float on the water surface and begin calling. Breeding activity begins as early as mid-April in some locations and can continue until late June in other, more northerly, regions. Mature females attracted by the calling of the males arrive several days to several weeks later. Each female mates only once, and lays a single egg mass in shallow water, usually on vegetation. Females can lay as many as 7000 eggs each, although half this amount is more common. The eggs hatch in 9 to 14 days, depending on water temperature. Tadpoles initially remain close to the egg mass after hatching, but disperse after a few days. Free-swimming tadpoles feed on floating vegetation and dead and decaying organic matter. Tadpoles take 60 to 90 days to complete their metamorphosis and transform into frogs. On average, less than 10% of eggs survive to become young frogs. Complete mortality can occur if breeding ponds dry too quickly. Predators of tadpoles include waterfowl, fish, frogs, snakes and a number of aquatic insects. Even if tadpoles manage to survive long enough to become frogs, only 40% of the frogs survive until the following spring. Northern Leopard Frogs typically spend much of the day sitting in leaf litter on a small patch of moist soil cleared of vegetation. They hunt primarily at night. Adult frogs feed on insects, spiders, worms, snails, slugs, small birds, fish, snakes and other frogs. Females reach sexual maturity at 55 to 60 mm in length, with larger females laying a larger number of eggs. Approximately one half of males reach sexual maturity in their second year, when they measure 51 mm. In the fall, Northern Leopard Frogs move to their overwintering sites, choosing water over land when air temperatures fall below 2ºC. They have been found up to 3 m below the ice hibernating in small excavations in the surface of the mud. The Northern Leopard Frog typically lives for a maximum of four to five years.
Northern Leopard Frog declines observed in many areas of North America are associated with habitat loss, degradation and fragmentation. The species’ diversified habitat requirements make it particularly vulnerable to such changes. Removal or modification of even one of the three habitat types used by Northern Leopard Frogs may render the landscape unsupportive of the species’ requirements. For example, in Saskatchewan, pressures on Northern Leopard Frog habitat, such as wetland drainage and pipeline and highway construction, are continuing occurrences. The species is also threatened by emerging diseases, such as chytridiomycosis, a disease caused by the chytrid fungus that has been linked to Northern Leopard Frog declines across North America. The introduction of non-native species, including invasive plants as well as fish species that prey on tadpoles and adults, is another major threat to the Northern Leopard Frog. Common carp, now prevalent in the Delta Marsh area of Manitoba, can displace Northern Leopard Frogs by modifying habitat and can reduce or eliminate algae and invertebrate populations. Introduced bullfrogs are an added source of predation in western Canada. Grazing cattle and other livestock can damage Northern Leopard Frog breeding, foraging, and overwintering habitat on the prairies. Livestock trample and reduce emergent vegetation and vegetative cover. This activity facilitates erosion, water contamination, and can disturb egg masses. Northern Leopard Frogs are very sensitive to environmental contaminants, and there is a large body of literature on the effects of pesticides on amphibians. Pesticides have caused reduced growth rates, paralysis and mortality in tadpoles. In addition, frogs exposed to contaminants are more susceptible to pathogens. Recreational collection of Northern Leopard Frogs continues in Alberta, even though it is prohibited. Recreational and commercial harvest is still permitted in Manitoba. Collection of individuals may contribute to the decline of the Western Boreal/Prairie population. Embryo mortality may be attributed to ultraviolet radiation, and Northern Leopard Frog egg masses are especially vulnerable as they are often deposited close to the water surface.
Federal ProtectionMore information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.
Northern Leopard Frogs (Western Boreal/Prairie populations) are protected under the Canada National Parks Act when they occur in Waterton Lakes and Wood Buffalo national parks in Alberta, in Grasslands and Prince Albert national parks in Saskatchewan, and in Riding Mountain National Park in Manitoba. One of the sites in Alberta is located in the Suffield National Wildlife Area, which is federal land protected under the Species at Risk Act (SARA). In Alberta, the species is also protected under the Provincial Wildlife Act. In Saskatchewan and Manitoba, it is protected in provincial parks. In western Manitoba, the Northern Leopard Frog occurs in most provincial parks, wildlife management areas and refuges in the southern region, where it receives some level of protection. In the Northwest Territories, the species is not protected under any territorial legislation.
Provincial and Territorial Protection
Recovery Progress and Activities
Summary of Progress to Date A multi-jurisdictional team is being assembled to prepare a management plan for the Northern Leopard Frog in Alberta, Saskatchewan, and Manitoba. Summary of Research/Monitoring Sighting report surveys conducted in 2006 are helping to define the Northern Leopard Frog’s distribution. Also in 2006, posters were distributed to solicit more information on the distribution of the Northern Leopard Frog in Alberta. Summary of Recovery Activities Fences are being erected along stream banks to prevent cattle from destroying the riparian habitat used by frogs. Erosion of stream banks is being addressed through habitat management activities. Landowners and lessees are being contacted and asked to adopt beneficial land management practices that will promote Northern Leopard Frog habitat.
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
13 record(s) found.
- COSEWIC Status Reports (2 record(s) found.)
- COSEWIC Assessments (2 record(s) found.)
- Response Statements (2 record(s) found.)
- Management Plans (1 record(s) found.)
- Orders (3 record(s) found.)
- COSEWIC Annual Reports (2 record(s) found.)
- Consultation Documents (1 record(s) found.)
COSEWIC Status Reports
COSEWIC Annual Reports
COSEWIC Annual Report - 2003 (2003)May 2003 Annual Report to the Canadian Endangered Species Conservation Council by the Committee on the Status of Endangered Wildlife in Canada.
COSEWIC Annual Report - 2009 (2009)2009 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
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