Northern Leopard Frog
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Northern Leopard Frog populations experienced drastic declines in Alberta near the end of the 1970s. Such declines in population were accompanied by changes in distribution in the province. Accordingly, descriptions of the distribution of Northern Leopard Frogs in Alberta are divided into "historic" and "current", based on whether observations were collected before and during, or after, 1980.
Many authors have shown the historic distribution of the Northern Leopard Frog to be continuous in Alberta, with the range including most of southern Alberta and a band running along the eastern border of the province north to the Northwest Territories. However, a review of museum collections and naturalists' records and published sources of information suggests that the species' range was largely restricted to two discontinuous parts of the province. These two areas include the Slave River valley and
Kazan Uplands in extreme northeastern Alberta and the
grasslands, parkland and
foothills of southern Alberta.
In the southern half of the province, the species' range extended across the
grasslands, foothills and parkland from the United States border north to Edmonton. Within this region, the Northern Leopard Frog was continuously distributed along major rivers and tributaries with scattered populations associated with lakes, springs and irrigation reservoirs. Although the
species appears to have been widely distributed in the western half of the central
parkland, there are only a handful of records from the eastern portion of the parkland north of the Battle River.
In southern Alberta, the western extent of the range was the foothills and the eastern periphery of the Rockies at lower elevations. There are records from the northeastern and eastern edges of
Waterton Lakes National Park and from the Bow Valley corridor near
Bow Valley Provincial Park and the Yaninuska Centre. Historic records from the mountains are lacking and the species has been considered to be of "hypothetical" occurrence in Alberta's Rockies.
Northern Leopard Frogs have also been observed along the Lesser Slave River, at
Lesser Slave Lake Provincial
Park, and at Thunder Lake, Long Lake and Cross Lake Provincial
Parks.
Since 1980, there has been a southern contraction of the provincial range of the Northern Leopard Frog, and the species now appears to be largely
extirpated from the central parkland, and is apparently absent from the entire North Saskatchewan River drainage. With the exception of the Kazan Uplands in northeastern Alberta, where there were observational records from Bocquene Lake in 1991 and from Wylie Lake in 1983, there have been no observations of Northem Leopard Frogs north of the Red Deer region since 1979.
In total, Northern Leopard Frogs have been observed at 84 locations since 1981 (with the vast majority occurring since 1990), but direct (tadpoles or developing or recently transformed young) or indirect (calling males) evidence of breeding has been reported from only 27 sites in the province.