Stinkpot (Sternotherus odoratus) COSEWIC assessment and status report: chapter 3

Species Information

Description

The stinkpot (Sternotherus odoratus) is known in French as “la tortue musquée” (Johnson 1989). This "surly-tempered little reptile" is so named for the musky odor it exudes from four glands located on the underside of the carapacial margins (Logier 1939). It is a small freshwater turtle with a highly arched carapace that rarely exceeds 13 cm in length. The carapace is grey-brown to black and the plastron is yellow to brown. The plastron is small and has a single inconspicuous hinge. The turtle's skin colour is grey to black and many individuals have two prominent light stripes on the side of the head. Males have longer tails, ending in a blunt terminal nail, and have more exposed skin around the median plastral seams than do females (Cook 1984). Males also have two conspicuous patches of scales on the inner surface of each hind leg.

Taxonomy

This species is a member of the family Kinosternidae, which is composed of four genera and 22 species (Cook 1984). Morphological evidence suggests that it may be more appropriate to consider the genus Sternotherus as a subgenus of the genus, Kinosternon, (Iverson 1991), thus renaming the stinkpot Kinosternon odoratus. There is still strong debate about this proposed change in the species' taxonomy and biologists continue to view Sternotherus and Kinosternon as separate genera (Ernst et al. 1994, Iverson 1998, Crother 2000). The stinkpot is the only species of the family Kinosternidae to range into Canada.

Research

The ecology of S. odoratus has been studied across most of the species' range, including Michigan (Risley 1933), Oklahoma (Mahmoud 1969), southeastern Pennsylvania (Ernst 1986), Virginia (Mitchell 1988), Alabama (Dodd 1989), and Ontario (Edmonds and Brooks 1996; Edmonds 1998). Most research has collected data on stinkpot demography (Tinkle 1961; Wade and Gifford 1964; Bancroft et al. 1983; Ernst 1986; Dodd 1989; Mitchell 1988; Meylan et al. 1992; Edmonds and Brooks 1996), or focused on aspects of stinkpot reproductive biology (Risley 1933; Tinkle 1961; Lindsay 1965; Mahmoud 1967; Gibbons 1970; McPherson and Marion 1981a,b; Mitchell 1985a,b; Ernst 1986). There are also some studies documenting aspects of stinkpot behaviour: such as, activity cycles (Risley 1933; Mahmoud 1969; Ernst 1986), home range and movements (Risley 1933; Williams 1952; Mahmoud 1969; Ernst 1986; Mitchell 1988; Edmonds 1998), courtship (Mahmoud 1967; Ernst 1986), nesting habits (Lindsay 1965; Ernst 1986), and feeding behaviour (Mahmoud 1968).

In Canada, research on the stinkpot is mostly confined to simple records of observation (e.g. Brunton 1981; Brunton and McIntosh 1985; Chabot and St. Hilaire 1991; Bendall 1959), compiled in the Ontario Herpetofaunal Summary (Weller and Oldham 1986) and at the Ontario Natural Heritage Information Centre (NHIC), in Peterborough, Ontario. Bendall (1959) described finding 12 stinkpot shells in a bald eagle nest at the Queen’s University Biological Station at Lake Opinicon. Lindsay (1965) described the nesting behaviour of S. odoratus in Frontenac District, Ontario. The only in-depth study on stinkpots in Canada focused on a population at the mouth of Twelve Mile Bay, in Georgian Bay, Ontario (Edmonds and Brooks 1996; Edmonds 1998). From 1991 to 1997, demographic parameters of this population (i.e. sex ratio, body size, growth rates etc.) were estimated and compared with those of more southern (U.S.) populations (Edmonds and Brooks 1996; Edmonds 1998). In 1995 and 1996, individual stinkpots were radio-tracked and movement patterns were described (Edmonds 1998).

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