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Western Painted Turtle (Chrysemys Picta Bellii)

COSEWIC Status Report
on the
Western Painted Turtle
Chrysemys picta bellii

Pacific Coast population
Intermountain – Rocky Mountain population
Prairie/Western Boreal – Canadian Shield population

in Canada

Species Information

Name and Classification

The Painted Turtle belongs to the genus Chrysemys. Although Chrysemys is among the most common and familiar genera of turtles, it contains only one species, Chrysemys picta (Scheider, 1783). Chrysemys picta was described from eastern North America, and the Western Painted Turtle (Chrysemys picta bellii; Gray, 1831) was recognized as a subspecies distinct from the Eastern Painted Turtle (C. p. picta) nearly 50 years later. In 1857, Agassiz recognized two additional subspecies: the Southern Painted Turtle (C. p. dorsalis) and Midland Painted Turtle (C. p. marginata) (Collins, 1997). All subspecies except C. p. dorsalis are found in Canada. Subspecies differ in the: (1) juxtaposition of vertebral and pleural seams; (2) lightness or darkness of these carapacial seams; (3) size of the central dorsal stripe; (4) carapace colouring; (5) plastron colouring; (6) extent of the plastral central marking and body size, with C. p. bellii being distinctly larger than the other three subspecies in both these respects (Ernst et al. 1994). Chrysemys p. bellii has a carapace with alternating vertebral and pleural seams, a poorly developed or absent mid-dorsal stripe, and a reticulate pattern of light lines. Its plastron is bright orange/red, with a central marking that extends along the seams to occupy most of the underside (Ernst et al.1994).

Patterns of morphological (Ultsch et al. 2001) and mt-DNA variation (Starkey et al. 2003) cast some doubt on the validity of current subspecific designations. The subspecies intergrade and a “pure” picta may not exist according to Ultsch et al. (2001): (1) there is marginata influence throughout picta’s range; (2) similarities exist between picta and dorsalis; and (3) there is a north-south cline that blends the characteristics of bellii with those of marginata. Starkey et al. (2003) suggest that the Southern Painted Turtle could be considered a distinct evolutionary species (C. dorsalis), and that C. dorsalis and C. picta may be best treated as monotypic. These authors are now investigating nuclear genes of the Chrysemys picta complex to refine species and subspecies boundaries.  At present, C. p. belliis regarded as a distinct and valid subspecies (Crother et al. 2000).

Morphological Description

Painted Turtles have low, smooth, oval, unkeeled carapaces (Figure 1), although the carapace of hatchlings tends to be rounder and slightly keeled along its length (Gregory and Campbell 1987). The Western Painted Turtle (C. p. bellii) is the largest subspecies, attaining a carapace length of 251 mm; females tend to be larger than males (Cook 1984). The C. p. bellii carapace is flatter than that of the other sub- species, with slightly different markings (Cook 1984). Carapace colour is brown, black, or olive green, and a central light yellow reticulated pattern or faint line may be present along the vertebral scutes (Gregory and Campbell 1987). The carapace of males is often marked with black reticulations (Cook 1984). The seams of the pleural and vertebral scutes are not aligned, similar to C. p. marginata, but contrasting with C. p. pictain which the seams are aligned (Cook 1984, Ernst et al. 1994). The plastron is orange-red (Stebbins 1966) and in all life stages, a dark pattern is located at the centre of the plastron, which branches out into the furrows between the scute margins (Figure 3). At hatching, plastron length is roughly 25 mm (Macartney and Gregory 1986). There are reddish markings on the bridge between the plastron and carapace. The head, tail and limbs of Western Painted Turtles are olive or blackish; there are yellow lines on the head and tail, and yellow dots on the limbs. The digits on the hind feet are deeply webbed. Males have much longer claws on the forefeet and their tails are longer and wider compared to females (Stebbins 1966; Gregory and Campbell 1987).

Figure 1: Photo of a Western Painted Turtle (Chrysemys picta bellii)

Figure 1: Photo of a Western Painted Turtle (Chrysemys picta bellii) photo by Bill Leonard.

Photo by Bill Leonard.

Figure 2: Faunal Provinces of Terrestrial Amphibians, Reptiles, and Molluscs in Canada

Figure 2: Faunal provinces of terrestrial amphibians, reptiles, and molluscs in Canada (map prepared by David M. Green, 2003).

Map prepared by David M. Green, 2003.

Figure 3: Ventral View of a Western Painted Turtle, Showing Plastron Colour and Patterning

Figure 3. Ventral view of a Western Painted Turtle, showing plastron colour and patterning; photo by Bill Leonard.

Photo by Bill Leonard.

Designatable Units

COSEWIC recognizes eight faunal provinces for the terrestrial amphibians and reptiles in Canada (Figure 2). The Western Painted Turtle occupies four of these. It is evident from comments from experienced observers, and from the number of occurrences, that this subspecies is faring quite differently across its Canadian range. In faunal provinces 4 (Prairie/Western Boreal) and 5 (Canadian Shield) (Ontario, Manitoba, Saskatchewan, and Alberta), the subspecies appears numerous and secure. The exception is Alberta where the subspecies is rare, and may have been introduced in some areas. In faunal provinces 2 (Intermountain) and 3 (Rocky Mountain) (British Columbia Southern Interior), the Western Painted Turtle is uncommon, and appears to be declining and threatened by loss of habitat, and increased mortality and population isolation and fragmentation from the expanding road network (J. Brown, pers. comm. 2005; P. Gregory, pers. comm. 2005; M. Sarell, pers. comm. 2005). The turtles in these regions are also isolated from other Canadian populations. Finally, the Western Painted Turtle also occupies faunal province 1 (Pacific Coast), which includes the southern Pacific Coast mainland and Vancouver Island. Again, these turtles are isolated from other Canadian populations. Furthermore, they exist in very small numbers with only a handful of records from this region. There is still some question whether the Painted Turtle is native or introduced to this area. However, records go back to the 1920s and with earlier anecdotal reports from Vancouver Island (F. Cook pers. comm. 2005). The current consensus seems to be that the main argument that they are not native is that they have always been rare (L. Friis, pers. comm. 2005, P Gregory, pers. comm. 2005). The Red-eared Slider (Trachemys scripta) is an introduced turtle that has rapidly increased in numbers and may be a threat to the Western Painted Turtle (F. Cook, pers. comm. 2005; P. Gregory, pers. comm. 2005; Bunnell 2005).

Therefore, given the disjunct populations found across the southern regions of British Columbia, and given the obviously different status of these populations: very uncommon in the coastal regions and declining in the southern interior, it is reasonable to treat these populations as three separate designatable units.