Painted turtle (Chrysemys picta) is currently a common species on Martha's Vineyard, easily observed sunning on logs and pond shorelines in every town on the Island. Because adult painted turtles are relatively large and easily seen, it's easy to assume that the species is thriving on Martha’s Vineyard. But hatchling and juvenile painted turtles do not sun themselves; they remain hidden in marshy areas around the edges of the ponds, where it is easier to avoid predators. Therefore, observation of the highly visible adult painted turtles tells us little about how many young are being recruited into the population over time. As with many other long-lived species, biologists worry that we may not notice declines in turtle numbers until it is too late to develop an effective response.
There is good reason for concern. While adult painted turtles are fairly large, wary, and well protected by thick shells, eggs, hatchlings, and juveniles are highly vulnerable to skunks, raccoons, crows, bullfrogs, and other predators. Even the casual observer has seen turtle nests depredated by skunks and raccoons before they hatch. In fact, most people don't even notice turtle nests unless they see the remains of eggs that have been unearthed and eaten by nest predators. How many hatchlings are actually living long enough to reproduce is unknown. In the spring of 2025, noted Vineyard wildlife biologist Dick Johnson urged BiodiversityWorks to take a look at this important question. While we didn't have the capacity to do so, given our many other projects, we were in luck: Oscar Thompson, formerly a BiodiversityWorks intern and seasonal technician and now a herpetologist/coastal ecologist for the University of Georgia, said he would be here for a few weeks in the summer and would love to conduct a pilot project to determine if a larger study would be warranted.
Oscar Thompson measuring a painted turtle in 2016.
Oscar was the perfect person to take on this task. In 2016, for his senior thesis project at Warren Wilson College, Oscar surveyed painted turtles in 26 ponds on Martha’s Vineyard. Using baited hoop nets, he captured a total of 226 painted turtles in 22 ponds. Due to the size of the trap openings and the habitat where hoop nets were set, Oscar mainly captured larger adult turtles; in fact only four of the 226 painted turtles were less than 80 mm long and considered juveniles. Thus, this extensive study provided little information about recruitment and the number of hatchling or juvenile turtles in the population. However, because fewer small individuals were captured in ponds located in areas with more development, Oscar hypothesized that rapid development of the island in the last several decades had led to higher nest loss to predators associated with development. In short, Oscar's study raised concerns of a painted turtle population dominated by large, long-lived females but with a low recruitment of new individuals. This would ultimately result in population declines as older females reached the ends of their lives without having successfully reproduced.
Oscar processing a painted turtle in 2025.
Because Oscar's original study did not assess juvenile painted turtle numbers, and no previous researchers had either, we currently have no data on juvenile painted turtle survival to adulthood. With Oscar on board again, we prioritized collecting baseline data on juvenile painted turtle numbers and survival on the Vineyard. The ultimate goal is to determine if young turtles are being recruited into the population in sufficient numbers to maintain a viable population, and if not, determine what steps might increase recruitment to a level sufficient to maintain a viable population. With limited time in 2025, we structured our first year of work as pilot season, surveying sites with known adult populations and testing methods to reliably capture juveniles and hatchlings. This preliminary work helped us assess the feasibility of a larger project in the future. With a grant the Johnson Family Foundation, the pilot study began in June 2025.
Larger hoop live traps used in 2016.
Oscar and volunteers Dick Johnson and Betsy Buck set traps in 11 pond across the island. They captured 53 painted turtles, three of which were juveniles — about 6% of the total captures, compared to just 2% in the 2016 study. This is a rough and preliminary result, complicated by the pilot study's short duration and the fact that smaller Promar traps may be more effective at capturing juveniles than were the larger hoop traps used in Oscar's 2016 project. But it's encouraging that juveniles continued to turn up in our 2025 sampling, and more importantly, this past summer's results suggest that our refined live-trapping methods are well suited for addressing the vital recruitment question.
In 2026, we plan to re-survey all of Oscar's sites from 2016, add some additional sites, and trap throughout the summer. This broader project will give us an enhanced understanding of painted turtle juvenile distribution and recruitment.
Smaller Promar live traps used in 2025.
Painted turtle #201 from Long Cove Pond in 2025 as an adult.
Another exciting result from our 2025 survey work was the recapture of six individuals that had been trapped and marked in 2016 during Oscar's initial survey. One of these recaptures, at Long Cove Pond on the Trustees of Reservations Long Point Wildlife Refuge, had been a juvenile in 2016! It was exciting to see this same turtle, almost 10 years later, grown to maturity. We hope that future studies will show many other young painted turtles enjoying similar success.
