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1. What you can do
5. Environmental Issues
6. Keystone species
7. Get Wet!-
Field Study Ideas
8. The Zoo Experience
9. Frogs & Friends
10. Case Studies
CASE STUDY 6: BLANCHARD'S CRICKET FROG(Level: 7 : 10 acad : 10 appl : 11 acad : 11 appl : 12 acad )
A small, non-climbing member of the tree frog Family (Hylidae), Blanchard's cricket frog (Acris crepitans blanchardi) is the most northern of the two cricket frog species endemic to eastern and central North America. Its range almost exclusively occurs in the US but extends to Point Pelee and Pelee Island in extreme southwestern Ontario. Mostly inhabiting the gently sloping, muddy or sandy shores of ponds, cricket frogs are the most aquatic members of North American Hylidae and remain in the vicinity of permanent water throughout the year.
In Canada, Blanchard's cricket frog has not been seen in Point Pelee since 1920, and is considered extirpated at this site. Despite many searches on Pelee Island since 1979, this frog has only been reported at Fox Pond in the Fish Point Provincial Nature Reserve. In 1984, 30 males were reported calling however, only 2 appeared in 1987. Since this time, there have been no substantiated reports of Blanchard's cricket frog, and it may be extirpated from Canada. A recovery team of amphibian scientists and conservationists has made recommendations for the recovery of Canada's rarest frog.
The decline or extirpation can be attributed to a combination of natural and human induced stresses upon a species existing at the edge of its range. Heavy predation at Fox Pond may be a possible cause for its loss at this location.
Pelee Island had a large interior marsh that was dyked and drained in the late 1800s. This marsh may have supported a large population of Blanchard's cricket frogs as apparently healthy populations were reported in the 1950s and early 1970s. Many of the recorded sites in the 1970s existed along the periphery of the island, which may have been destroyed by storms and fluctuating water levels in Lake Erie. Many of these sites were beach pools and marshes and were scoured by lake storms. Most of the remaining populations were in drainage canals that line Pelee Island roads. Periodic dredging of these canals likely killed many frogs, compounded by the close proximity to roads, posing a threat to migrating individuals. These canals also receive agricultural and road runoff of fertilizers, pesticides and salt, as most of the island is under cultivation.
The last known population of Blanchard's cricket frog was located in a naturally occurring, large, shallow marsh on Pelee Island. Fox pond, located in the Fish Point Provincial Nature Reserve is isolated from roads, fields and human activity, as well as having legal protection although not patrolled or actively managed. A large bullfrog population, the introduction of raccoons as well as predatory species of birds, turtles, and snakes feed at this site. Heavy predation is considered to be one of the major causes for the disappearance.
In some cases of extirpation, the possibility of migration of the species from a nearby area may repopulate the lost population. However, in this case, the nearest population of Blanchard's cricket frogs are also in decline and are separated by Lake Erie. The artificial introduction of the cricket frog poses a host of other problems. Because Pelee Island land use is primarily agriculture, most suitable habitat is likely lost. The lack of knowledge about this species in Canada makes comparisons with other US species difficult. A recovery team of experts has written a Recovery Plan. Must we face the fact that Blanchard's cricket frog is lost from Canada indefinitely?
1. Do you feel that the decline and ultimate extirpation of the cricket frog from Canada is a natural occurrence, considering that this species existed on the edge of its range, in an area initially affected by storms and flooding?
2. Is it "appropriate" to use (US) potentially different genetic sources to re-establish a Blanchard's cricket frog population on Pelee Island, particularly if other populations are already in decline?
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