Spotted Turtle Research and Tracking

Spotted turtles

(Clemmys guttata)

Spotted Turtles are one of the five species of turtles on Martha’s Vineyard and are found in a variety of wetland habitats including shrub swamps, cranberry bogs, and wetlands dominated by spaghnum moss hummocks. They have a black carapace with several tiny yellow spots and orange to black skin with yellow spots on their head, neck, and legs. They are a long lived species some living over 100yrs!

Carapace (left) and plastron (right) of a spotted turtle.

Spotted turtles are identified as Species of Greatest Conservation Need (SGCN) in all 21 states in which they occur, and have been petitioned for federal listing under the Endangers Species Act in 2023. The Status Assessment and Conservation Plan for the Spotted Turtle in the Eastern United States is a collaborative effort among biologists from Maine to Florida focusing on a standardized population assessment to establish baseline population data, inform adaptive management strategies, and identify priority habitat and population management actions. This project includes live trapping for population estimation and genetic sampling. BiodiversityWorks joined the effort in 2020 to include data from Martha’s Vineyard. The last published data on spotted turtles on Martha’s Vineyard was in James Lazell’s book, “This Broken Archipelago: Cape Cod and the Islands, Reptiles and Amphibians” from 1976. Since then there has been a few sighting but otherwise little was known about the status of our spotted turtle population.

Spotted turtles are found in a variety of wetland habitats including shrub swamps, cranberry bogs, and wetlands dominated by spaghnum moss hummocks.

Methods

In 2020, we live-trapped spotted turtles at 4 sites (Aquinnah, Squibnocket, Oak Bluffs, and Chappaquiddick). We also conducted visual surveys along Moshup Trail.
In 2021, we live-trapped spotted turtles at 4 sites (Squibnocket, Oak Bluffs, Edgartown and Chappaquiddick)
We set 5-20 Promar minnow traps baited with sardines at each site. Traps were set for 4-12 nights and checked daily.

Spotted turtles caught were measured and given an identifying notch on their outer scute using a numerical notching system.
9 spotted turtles were fitted with a small radio transmitter to document movements, habitat use, and potentially lead us to other spotted turtle populations.

A spotted turtle recently fitted with a small radio transmitter. We will follow this turtle once per week to document its habitat use and movements.

Each turtle gets a unique notch on its outer scute so that we can identify it for years to come and monitor its growth and the population.

Results

Through trapping, tracking, and reports from the community we have documented 27 spotted turtles on Martha’s Vineyard at 5 different locations. It is difficult to determine if our populations are low or these turtles are difficult to detect. It may be a little of both! Historic sites on the Vineyard, or areas with one sighting, may have persisting populations. There may also be other places on the island with small undetected populations. We hope to continue to get reports from the community and map locations of these elusive turtles. Even though these turtles are secretive and difficult to locate we now have baseline information.

Map showing areas surveyed in 2020 and 2021 for spotted turtles. Edgartown and Squibnocket had the largest populations of spotted turtles.

Tracking Highlights/Results

In 2020 we placed transmitters on 4 turtles Clovis and Myrtle in Oak Bluffs and Clementine and Lizzie in Squibnocket.
In 2021, we placed transmitters on Gladys and Wilson in Oak Bluffs, Peanut in Squibnocket and Felix and Bart in Edgartown
Spotted turtles typically estivate for the summer and make very few movements. In 2020 turtles in Squibnocket moved into the uplands when their wetlands dried up but in 2021 a very wet summer allowed them to stay in their wetlands. This highlighted the importance of having a good upland buffer around all wetlands for estivating and nesting.
Three spotted turtles were found using salt marshes, which is unusual for spotted turtles.
We found spotted turtles are home bodies and don’t move much. Big movements documented were during the nesting season and were likely females moving to and from their nesting sites. Clovis the male in Oak Bluffs seems to be the most active changing locations frequently.
In Squibnocket particularly, our tagged turtles have led us to new pools and habitats – Squibnocket’s habitat is well connected which allows for easy movement of the turtles into new pools – through tracking these turtles we have been able to trap in new locations and expand our efforts.

Tracking spotted turtles has shown us how little they move and how secretive they can be or difficult to detect. It is possible there are other populations of spotted turtles hidden on the island or more turtles in our known sites.