A post about turtles and my citizen science effort which suffered serious technical glitches and yielded challenging data.
Turtles have always meant a great deal to me. In my preteen years I kept several box turtles, an action I now regret but one that reflected my early embrace of the natural world. I have long appreciated the uniqueness of the turtle with its remarkable body plan that has served it well until the present. Unfortunately, the world now poses such serious threats to these iconic creatures that I fear most won't survive the Anthropocene.
A little more than a decade ago, I started a project recording each sighting of an eastern box turtle (Terrapene carolina carolina) that appeared during the middle of the summer around my cottage on the north fork of the eastern end of Long Island. The sightings have been infrequent which is not surprising given the decline of the reptile's population in the northeastern United States. New York State considers their status to be of "Special Concern." (Lori Erb and H. Patrick Roberts, Status Assessment for the Eastern Box Turtle in the Northeastern United States, Final report to the Northeast Association of Fish and Wildlife Agencies for a Regional Conservation Needs award, 2023, p. 18-21.)
The threats to these animals are many, among the most serious according to a poll of experts are roads, development, and habitat loss (Figure 12 in Erb and Roberts, p. 31.) I think perhaps the most substantial negative factor impacting their survival is the low rate of reproduction. In the Northeast, females are likely to lay their first clutch of eggs at 14 years of age and may not lay eggs every year. (Erb and Roberts, p. 11.) This makes the loss of any one female turtle a significant blow to the population.
T. c. carolina is a subspecies of T. carolina, and is found across the northeastern U.S., from New England to Georgia, and as far west as southeastern Arkansas and Illinois. The other subspecies of box turtles in the U.S. include the Florida box turtle, the Gulf Coast box turtle, and the three-toed box turtle. (Carl H. Ernst and Jeffrey E. Lovich, Turtles of the United States and Canada, second edition, 2009, p. 410.)
This year my anxiety level over the immediate local threats to the turtles inhabiting the wooded and developed land abutting the cottage has risen markedly. In particular, planned and actual fence-building by my neighbors, prompted partly by a ridiculous feud, poses a real challenge to survival of these animals here. Fences can fragment the habitat the turtles occupy, keeping them from the resources they need and isolating populations (potentially adversely affecting the gene pool). This fencing activity is particularly distressing because 2024 has been a sort of banner summer for turtle sightings here. "Banner" is, of course, relative: this year I have recorded sightings of three individual eastern box turtles, which is actually a robust annual number for me. Two of them appear to be new to my survey (first two shown below), and one is a true old-timer that was first spotted in 2014 (last one shown below).
Since 2012, I have recorded sightings of perhaps 13 individual box turtles. There's a lot embedded in that "perhaps." Even if everything had gone right (it didn't), there is an inherent margin of error in my effort to gather information on unique representatives of T. c. carolina. The only attribute I've used to distinguish among individual turtles (except for the single juvenile in the database) is the markings on their carapaces. I understand that these patterns are similar to our finger prints, each display is unique to an individual box turtle. (National Park Service, Species Spotlight: Woodland Box Turtles: Terrapene carolina carolina, updated September 8, 2023.) Still, using this feature to identify individuals introduces a margin of possible error because, though some patterns are quite easily differentiated, others are not.
Nevertheless, that built-in potential source of error in my methodology is not the reason I've been fumbling this project. The problems I've encountered go beyond telling patterns apart; they arise from having relied for over a decade on a particular piece of technology to record and maintain images and data. In that time period, the database app I used, primarily on my cellphone, went from being well supported to being orphaned, with no updates and little support. Even worse, I upgraded my phone several times and ultimately one of those upgrades blew up the app, leaving much of the data intact but separating images of turtle carapaces from their data base entries. Only after painstaking scouring the metadata of the turtle pictures I'd backed up for the dates on which the images were taken originally, was I able to reconstruct (mostly) the database. Did I resolve all of the glitches? No. Did I do enough to have confidence in validity of the data and images I've put into a new database app? Yes.
When I initially considered the data I'd gathered since 2012, I found it decidedly challenging to interpret them. They seemed significantly skewed. Here is the central issue I wrestled with: the data, with few exceptions, describe individual turtles spotted only a single time. The vast majority of individual turtles in the database (nine of thirteen) have been encountered just once. An additional three appeared only twice in two different years. The single individual appearing more than twice is the third one shown above, to which I'd given the ID # of 14-1. It has been sighted 13 times since 2014.
To make sense of this, I read back through my principal resources (cited previously in this post) with these findings in mind. As I did, I kept coming back to what the research says about turtle home ranges because that seemed to offer some explanation of the data I generated. I also kept in mind the serious threats to their survival that these animals face. I believe that these two factors - movement in home ranges and mortality - help explain my data. A third, related to home ranges, also played a role: the passivity of my effort. I did not go in search of box turtles, in essence I let the reptiles come to me. Perhaps there's little particularly surprising in this constellation of factors but it took me a while to recognize them. Let me lay out my thinking.
Single sightings dated back in the earliest years of my recording may well reflect turtle mortality, but not necessarily. Ernst and Lovich report that that box turtle home ranges overlap and that "a substantial proportion of a box turtle population at any time and place is made up of transients." (p. 417) Perhaps some or most of these sightings were of individuals that were "just passing through" to other areas and are still alive. My passive approach to finding turtles increases the likelihood of that. (The authors acknowledge that the transients make estimation of turtle population size challenging.)
I am a bit more comfortable believing that recently spotted newcomers (such as the four turtles appearing only once in the past four years) are likely to be still with us, though possibly going to live out their lives in ranges away from the environs of my cottage. Of course, only time will tell for any of these individuals.
The number of appearances of 14-1 indicates that this turtle likely has been spotted in her home range to which she appears quite dedicated. No doubt my cottage is in a core portion of that range. I do not know her age now or when I first encountered her (based on her size then, she was unlikely to have been a juvenile). She's certainly more than 10 years old. That she has survived so long despite the dangers of living in such close proximity to human activity is a cause for celebration. Ernst and Lovich report that, although T. carolina can live for a century or more even in the wild, "only few wild individuals live more than 25-30 years." (p. 422)
I acknowledge that this citizen science project of mine hasn't added much, if anything, to knowledge of eastern box turtles (though it has increased my own knowledge), or is of any measurable benefit to the box turtles who live near me. Still, I take some comfort in knowing that, in working on this project and sharing my interest with family and friends, I may have heightened their concern about the fate of these wonderful reptiles.
In closing, I will note that perhaps the most effective way I have actually helped the local turtle population is through my financial support of Turtle Rescue of the Hamptons. This summer, for the first time, I visited nearby Turtle Manor, the center of operations of this organization which is making a real difference in the lives of local turtles.
Headed by Karen Testa, a wildlife rehabilitator licensed by New York State, the organization works diligently
to rescue, rehabilitate and release wild chelonian species native to Long Island, to provide a sanctuary with a high quality of life for those who have sustained a permanent disability, and to allow injured animals to live out their lives with dignity and respect. (Turtle Rescue website.)
Turtle Manor, a converted farmhouse, has the capacity to care for and rehabilitate more than 200 turtles each year. It's not just box turtles to which the organization ministers, though I find particularly inspiring the pictures on the Turtle Rescue website of box turtles with broken carapaces taped back together. (Ernst and Lovitch note that "the eastern box turtle's shell has great regenerative powers." p. 422) I salute the organization's stellar work, but also recognize that this facility and the hard work of everyone involved alone cannot meet the needs of these special reptiles at this time in this area.
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