Montana Field Guide

EGGS:
Eggs of the Painted Turtle (Chrysemys picta) are white, smooth, and oval. They are approximately 31 mm (1.2 in) long. Initially flexible, the shell gradually becomes firmer as water is absorbed (Ernst et al. 1994, Werner et al. 2004). Clutch size can range from 6-21 leathery eggs (Ernst et al. 1994, Russell and Bauer 2000). In southern Canada, clutch size is 20 and in Wisconsin and Minnesota, clutch size was documented as 10 (Christiansen and Moll 1973). In Wisconsin, 50% of females laid two clutches and nested from June to mid-July. Eggs may overwinter (Ernst 1972).

HATCHLINGS:
Hatchlings have a keeled carapace and vivid orange plastron (Hammerson 1999).

JUVENILES AND ADULTS:
Painted Turtles are named for their highly decorative yellow or reddish orange markings on its carapace and yellow markings on its legs, tail, and head. The plastron (underside) is a brilliant yellow or reddish orange with a large olive, loosely symmetrical blotch in the center, while the carapace (top) is mainly olive to black with more distinct yellow or reddish orange markings along its outer edge. Striking yellow lines along the head and neck, and a red spot behind the eye are distinctive for this species. Yellow markings on the fore and hind legs and tail are also present, but less obvious than those on the head. Brighter than adults, juveniles are otherwise similar in coloration. Adult females are larger than males; carapace length can vary from 8-18 cm (3.2 to 7.1 inches) (Werner et al. 2004). Mature males have a flat plastron, long forefeet claws, and rear vent located beyond the edge of the carapace, while the claws on the forefeet of the female are relatively short with the vent located at or inside the rear edge of the carapace (Hammerson 1999). Juveniles are distinguishable by a deep crease in the abdominal plastron shields (Hammerson 1999).

Lacking the distinct bright coloration, it is unlikely other turtle species in the state would be confused with the Painted Turtle. The Spiny Softshell (Apalone spinifera) is smooth and creamy light brown in coloration with a relatively pointed head and flat pancake-like appearance. The Snapping Turtle (Chelydra serpentina) has a dark brown, grey, or black carapace without contrasting coloration patterns anywhere on the shell or body. The Spiny Softshell is found in the central and eastern portions of the state, along the Missouri and Yellowstone Rivers and their main tributaries, while the Snapping Turtle is limited to the central and southern portions of eastern Montana (Werner et al. 2004) with non-native populations located west of the Continental Divide (MTNHP POD 2022).

An animal of aquatic environments, the Painted Turtle prefers slow-moving shallow waterways (streams, marshes, ponds, lakes, and creeks) with soft mud bottoms and aquatic vegetation. They have been documented in glacial lakes (Franz 1971); but not found in oligotropic mountain lakes above 1,025 m (3363 ft) in Mission Mountains (Brunson and Demaree 1951). Partially submerged logs and rocks for basking are desirable habitat features. This turtle species may colonize areas only seasonally wet but must return to permanent waters for winter hibernation. Behaviorally, juveniles and hatchlings may differ from mature individuals in habitat use. For example, in Michigan, Congdon et al. (1992) found that the hatchlings and juveniles were found in more shallow areas of marsh habitat. This behavior could result from greater food resources available or an attempt to avoid the larger predators present in deeper water (Hammerson 1999). Painted Turtles hibernate in mud at the bottom from early October to mid- or late April. Nests are placed in terrestrial habitats and may range up to 600 meters from water, where the eggs are left to incubate on their own (Ernst et al. 1994, Hammerson 1999)). In southern Canada, nest have been found on south-facing grassy slopes (MacCracken et al. 1983). In small marsh systems, the home range size may be very small (e.g., average of 1.2 ha in Michigan) (Rowe 2003), whereas in rivers, individual home range sizes are generally much larger (e.g., 7-26 km or 4.3-16.2 mi) (MacCulloch and Secoy 1983, NatureServe 2006).

Ease of capture and size are major influences on what prey is taken. Food quality (animal vs. plant) and quantity may influence reproductive potential (MacCracken et al. 1983). Plant material was a significant food item (21 to 61%) in some Painted Turtles that had stopped growing. In addition to living and dead plants, Painted Turtles may consume a wide variety of living or dead organisms. In southern Saskatchewan, Painted Turtles preferred animal food (over 87% by volume) over abundant vegetation. Food interests include worms, leeches, insect larvae, pupae, and adults, as well as beetles, damselflies, dragonflies, water striders, water mites, spiders, mayflies, springtails, mosquitoes, crustaceans, snails, clams, frogs, and fish (Ernst et al. 1994, Hammerson 1999).

Most nesting occurs during the afternoon hours, with a smaller proportion of nests initiated in the morning (Ernst et al. 1994). Nesting may occur early or late into the summer. Nests that hatch later in the breeding season may exhibit delayed emergence, e.g., the young overwinter in the nest. Even though Brettenbach et al. (1984) found greater survivorship of nests in Michigan if covered by a beneficial layer of snow, substantial mortality of overwintering hatchlings can occur (Nagle et al. 2000). Nest mortality (resulting from predation) can be high, especially for those nests placed closer, rather than farther, from a water source (Christens and Bider 1987). In Christens and Bider’s (1987) study, hatchlings overwintering in the nest survived early predation, suggesting that open nests may trigger olfactory clues and make early predation more likely.

Adult mortality can occur for individuals overwintering in areas prone to both drought and widely ranging winter temperatures. Christiansen and Bickham (1989) discovered more than 100 painted turtles frozen to death when the pond in which they were hibernating had frozen to the bottom. A 1995 mortality study (Fowle 1996) reported most Painted Turtles found dead on road occurred from late May to mid-July and consisted of 43% adult males, 26% adult females, and 31% of unknown sex, including juveniles. Densities of adult Painted Turtles were positively correlated with pond distance from the highway, and proportionally more juveniles and fewer adults were found at ponds closest to the highway, implying that roadkill mortality may be killing proportionally more adults (Fowle 1996).

Sexual maturity appears more a consequence of size in males. Maturity occurs when plastron lengths are 70-95 mm (2.76-3.74 in), rather than age, and enhanced growth can shorten the average age of maturity of four years to two (Ernst et al. 1994). Females generally mature at 6-10 years of age at which time their plastron length ranges from 97-128 mm (3.8-5.1 in) (Ernst et al. 1994). Painted Turtles become active in late March or early April and may be observed basking on sun exposed banks, rocks, or logs in ponds, lakes, reservoirs, and streams. Nesting generally occurs from May until mid-July, with most nesting activity in June and early July. Christens and Bider (1987) found a consistent correlation between the mean temperature of the previous year for the current year’s nest initiation date for nests in Quebec, Canada. The flask-shaped nests are dug with the hind feet into rain-soaked soil, or soil sometimes softened with bladder water during digging (Ernst et al. 1994). Nests are dug into sandy, loamy, or other friable soil (Russell and Bauer 2000). Nest digging and egg laying can take up to four hours (Ernst et al. 1994), after which the eggs are covered over with soil. Poor weather conditions, such as extreme heat or drought can delay nesting (Lindeman 1989, Ernst et al. 1994).

Nest placement and the associated microsite characteristics are important as the sex of the incubating eggs is determined by temperature (cooler temperatures produce males, warmer produce females). While females may lay up to three clutches of eggs in one breeding season, Iverson and Smith (1993) reported an unusual 4 clutches for two females. Tinkle et al. (1981) estimated that 30-50% of females may not reproduce every year. Egg size and clutch size increase with female body size (Hammerson 1999).

A 1995 study from the Mission Valley in Montana (Fowle 1996) reported gravid females ranging from 7 to 17 in age, with smallest gravid female plastron lengths/widths of 166 and 82 mm (6.5 and 3.2 in) for 11- and 9-year old, respectively. The youngest males with secondary sex characteristics were 2 years old, with minimum plastron lengths/widths of 33 and 49 mm (1.3 and 1.9) for 4- and 3-year old, respectively (Fowle 1996).

The following was taken from the Status and Conservation section for the Painted Turtle account in Maxell et al. 2009.

The Painted Turtle is the most abundant turtle species in Montana; both the Spiny Softshell and Snapping Turtle have much smaller ranges, fewer recorded observations, and are more likely to be collected for harvest (Maxell and Hokit 1999, Werner et al. 2004). At the time when the comprehensive summaries of amphibians and reptiles in Montana (Maxell et al. 2003, Werner et al. 2004) were published, the Painted Turtle was documented in 41 counties, and broadly distributed across both the western and eastern portions of the state. Counties absent of records are generally located in the central portion of the state. State records are comprised of 392 observations in 40 counties, with 60 museum voucher records from 19 counties. The distribution of this species reflects its relative abundance compared to the two other turtle species in Montana. Specific state status information on the Painted Turtle is not available for Montana. Global trends over the short term are identified as stable, and relatively stable over the long term (NatureServe 2006).

Studies identifying or addressing specific risk factors for Chrysemys picta in Montana are lacking; however, documented studies and other issues pertaining to their conservation include the following: (1) During the breeding season, females are quite sensitive to disturbance while on nesting forays; human activity (e.g., fishing) can disrupt nesting activity even from a distance (Hammerson 1999). (2) Artificially high mammalian predator numbers resulting from human augmented food resources can result in lower abundance of local turtle populations. While the Raccoon (Procyon lotor) is the most detrimental native predator in all life stages of this turtle species (Ross 1988, Ernst et al. 1994), other native predators of Painted Turtle nests include the Thirteen-lined Ground Squirrel (Ictidomys tridecemlineatus), Chipmunk (Neotamias), Squirrel (Sciurus), Striped Skunk (Mephitis mephitis), American Badger (Taxidea taxus), Coyote (Canis latrans), Red Fox (Vulpes vulpes), Common Raven (Corvus corax), Plains Garter Snake (Thamnophis radix), and other snakes (Coluber). Hatchlings and small juveniles may fall prey to Giant Water Bugs (Belostomatidae), Hammerson 1999). Young Painted Turtles are under threat of predation by Muskrats (Ondatra zibethicus), American Mink (Neogale vison), Raccoon, Snapping Turtles (Chelydra serpentina), snakes (Coluber), American Bullfrog (Lithobates catesbeianus), large fish (Micropterus, Ictalurus), herons (Ardea), and Giant Water Bugs (Hemiptera) (Ernst et al. 1994, Maxell and Hokit 1999). In addition to Raccoons, adult Painted Turtles may be preyed upon by Bald Eagles (Haliaeetus leucocephalus), Osprey (Pandion haliaetus), and hawks. (3) Fowle’s (1996) mortality study in Montana reported most Painted Turtles found dead on the road occurring from late May to mid-July consisted of 43% adult males, 26% adult females, and 31% of unknown sex, including juveniles. Densities of adult turtles were positively correlated with pond distance from the highway, and proportionally more juveniles and fewer adults were found at ponds closest to the highway, implying that roadkill mortality may be killing proportionally more adults (Fowle 1996). (4) Ernst (1999) notes that, notwithstanding all of the potential wild predators, the greatest source of mortality for Painted Turtles is probably human caused: road kills, habitat destruction, pet trade, indiscriminate shooting and pesticide poisoning.