AMPHIBIANS AND REPTILES
Michael J. Oldham
AMPHIBIANS AND REPTILES
The Mixedwood Plains Ecozone has a more diverse amphibian and reptile fauna (collectively called herpetofauna, herptiles or herps for short) than any other Canadian Ecozone. However herpetofauna as a whole are much more abundant in more southerly latitudes and decrease in diversity as one moves north. Only one Canadian species, the Wood Frog (Rana sylvatica), ranges north of the Arctic Circle. Because most Canadian amphibians and reptiles are at their northern range limits and barely enter the country, many are on provincial and national lists vulnerable, threatened and endangered species lists. Amphibians and reptiles are also thought to be good indicators of environmental change, in part because of the dependence of many species on both aquatic and terrestrial habitats.
The 51 native species found in the Mixedwood Plains Ecozone (Appendix 1) are almost equally divided between amphibians (25 species) and reptiles (26 species). Of these species, 12 have their Canadian distribution restricted to the Mixedwood Plains Ecozone, while 19 species are widespread and range over much of southeastern Canada. Conservation Data Centres (or Natural Heritage Programs) in Ontario and/or Quebec currently track (consider to be of conservation concern and gather data on) 31 species or 61 percent of the herpetofauna in the Mixedwood Plains Ecozone (Oldham 1997, The Nature Conservancy 1998). Conservation Data Centres generally track species occurring in fewer than 100 locations in their jurisdiction.
Non-native species do not figure prominently in the Canadian herpetofauna. In the Mixedwood Plains Ecozone two turtle species, Eastern Box Turtle (Terrapene carolina carolina) and Red-eared Slider (Trachemys scripta elegans), are occasionally encountered. The former species has been found in aboriginal burial sites in southwestern Ontario, but since Box Turtles were popular trade items, it is thought that they probably came to Canada via trade. More recent records are probably based on released or escaped captives (Cook 1984). Red-eared Slider is the most common turtle species available in the pet trade and the individuals which are occasionally found in the wild (e.g. Darbyshire 1997) are presumably former captives. Although they have successfully overwintered in Ontario (Oldham and Sutherland 1996), there is no evidence of successful reproduction in the wild in Canada.
Several reptile taxa in the Ecozone are of global conservation concern. The Lake Erie Water Snake (Nerodia sipedon insularum), a subspecies of the Northern Water Snake (Nerodia sipedon), only occurs on islands in western Lake Erie where it is thought to have recently evolved (King and Lawson 1997). It is listed as Endangered in Canada and Ontario and is a candidate for listing under the federal Endangered Species Act in the United States. The Eastern Fox Snake (Elaphe gloydi) occurs only in Ontario, Michigan, and Ohio, and much of its global distribution is within the Mixedwood Plains Ecozone. The Eastern Massasauga Rattlesnake (Sistrurus catenatus catenatus) has declined dramatically throughout most of its midwestern North American range. Today populations in the Bruce Peninsula and southeastern Georgian Bay region of Ontario may be the best remaining anywhere. Wood Turtles (Clemmys insculpta) are of increasing conservation concern in North America, largely due to high demand in the pet trade. This species is now listed on Appendix II of the Convention on International Trade in Endangered Species (CITES).
Nationally, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) has designated 10 species occurring in the Mixedwood Plains Ecozone as Vulnerable, Threatened or Endangered in Canada, and another 15 species are under review or are candidates for review. Perhaps most alarming is the fact that three species formerly occurring in the Mixedwood Plains Ecozone and nowhere else in the country (Eastern Tiger Salamander (Ambystoma tigrinum), Blanchard’s Cricket Frog (Acris crepitans blanchardi), and Timber Rattlesnake (Crotalus horridus)) have apparently disappeared from Canada. All three were at one time found in southwestern Ontario, but their continued existence here seems doubtful.
Provincial and/or national (under the RENEW, Recovery of Nationally Endangered Wildlife, program) recovery teams have been set up to formulate and implement recovery plans for several amphibian and reptile species deemed to be at high risk: Blanchard’s Cricket Frog, Wood Turtle, Eastern Spiny Softshell (Apalone spinifera spinifera), Blue Racer (Coluber constrictor foxi), and Eastern Massasauga.
Amphibians have been the focus of considerable interest in recent years due to unexplained declines in several areas of the globe. Herpetologists gathered at the First World Congress of Herpetology in England in 1989 first sounded the alarm. After that meeting a Declining Amphibian Populations Task Force (DAPTF) was established as a working group within the Species Survival Commission of the World Conservation Union (IUCN). Various regional working groups were then set up to report to the DAPTF, with the Canadian group, Canadian Declining Amphibian Populations Task Force (DAPCAN), established in 1991. An initial report was prepared by this group in 1992 (Bishop and Pettit 1992) and a more detailed volume was published in 1997 (Green 1997). Annual conferences, organized by DAPCAN, to discuss amphibian decline and conservation issues have been held in various parts of Canada since 1991.
Despite the interest in declining amphibian populations, amphibians and reptiles are more poorly known than other vertebrate groups. Distribution, status, taxonomy, ecology and habitat requirements are still being worked out for many Canadian species. New discoveries and range extensions are still being made. The Mountain Dusky Salamander (Desmognathus ochrophaeus) was only recently discovered in Canada in southern Quebec (Sharbel and Bonin 1992), while the presence of the Northern Dusky Salamander (Desmognathus fuscus) was only recently confirmed in Ontario (Kamstra 1991). Provincial atlas projects in Quebec (Bider and Matte 1996, Matte 1997) and Ontario (Weller and Oldham 1986, Oldham and Weller in preparation) have resulted in many range extensions and a great deal of new distributional information. Several regional herpetofaunal surveys have also made significant contributions (e.g. Lamond 1994, Christie 1997).