Jeff Goessling

As uplands across the southeastern US confront a burgeoning human population, native ecological communities are increasingly stressed by increased predators via urban subsidies to native and invasive predators. Due to a long-standing successful habitat conservation and management program, a natural population of gopher tortoises (Gopherus polyphemus) remains in an urban nature preserve in St. Petersburg, Florida. An ongoing long-term study of tortoises at the site has identified more than 200 unique individual tortoises in this population. Between summer 2023 and 2024, however, more than 20% of the adult tortoise population was found to have been killed by coyotes, which are an invasive species in Florida. The depredated shells of many previously marked, healthy, and reproductive adult tortoises were found across the site and frequently cached and surrounded by coyote scat. Many of these shells were broken throughout individual bones (consistent with a large-gaping canine predator), not just along bone sutures. Three caches of tortoise shells also included other similar-sized carcasses of two other species (domestic cat, Felis catus, and nine-banded armadillo, Dasypus novemcinctus). An unquantifiable number of juvenile and hatchling gopher tortoises have also recently been killed by coyotes at the site, as evidenced by coyote scat in an adult tortoise shell cache containing hatchling tortoise shell scutes. Given the high number of previously-marked and well-studied but recently-depredated tortoises that have been recovered, this presentation will focus on the demographic features of the depredated population (including, sex, size, social network status, and reproductive output of the dead animals). Lastly, we will put this into a broader context and discuss the viability of >20% annual adult mortality and how this should impact regional management of invasive coyotes and this rapidly-declining ecological community.

Large-scale Gopher Tortoise translocations are a widespread practice to remove tortoises from imminent dangers of habitat loss for human development. However, translocation for explicit conservation goals remains an infrequently-utilized and untested tool to conserve this at-risk species. Given the effects of density on tortoise movement and population viability, we conducted a conservation effort to increase the population density of a low-density tortoise population on a public property in southern Alabama. Efforts included consolidating the resident tortoises from a fire-suppressed landscape into a temporary enclosure located in a high-quality restored sandhill. We also headstarted two cohorts of hatchlings from the site for one and two years. In total, 100 resident tortoises were consolidated into the enclosure and 98 headstarted juvenile tortoises were released into the nearby area into both soft- and hard-release conditions. Using radiotelemtry of a sub-population of consolidated adults tracked for two seasons (before and after the enclosure was removed), we found that site fidelity of the adults was 69% in the area enclosed by the pen and 93% in the wider-managed site. Adult home range area was not significantly different between the years that adult tortoises were enclosed in the pen and the year after the pen was removed. A subpopulation of two-year old headstarts was also radiotracked. Radiotracked headstarts had 100% site fidelity, regardless of release condition, and home ranges significantly decreased over the study period. Mortality was extremely low in all groups. We further discuss how this research may contribute to effective strategies for the demographic management of low-density tortoise populations, particularly in the species’ distributional periphery.

Recent technological advances have allowed wildlife ecologists to begin to understand the complexity of relationships among individuals within populations. Given gopher tortoises have high site fidelity, naturally exist in high population densities, and are long lived, their population social structures may be among the most complex within Reptilia. Prior studies have demonstrated that gopher tortoises form non-random interactions with each other, described as “cliques” in a southern Georgia population of tortoises. Herein, we tested for the presence of this complex social structure at Boyd Hill Nature Preserve in Pinellas County, FL, using camera traps placed at 12 active tortoise burrows and set to record every 5 seconds for an entire year during daylight hours. We found that cliques are not present within this population when we only considered social interactions as co-occurrence of two individuals. However, when we only considered interactions to be positive, namely burrow sharing between same- or opposite-sex pairs and burrow chasing between opposite-sex pairs, we found that cliques were significantly present. This study has implications for basic understanding of sociality in turtles and also conservation efforts for this intensively-managed species. 

Camera trap time-lapse recordings can collect vast amounts of data on wildlife in their natural habitat. Transforming these data into information useful to ecologists is a major challenge. Machine learning techniques show promise for becoming important tools to meet this challenge in a cost-effective way. Over the past year, we recorded 5-second interval time-lapse video of twelve active gopher tortoise burrows at Boyd Hill Nature Preserve in St. Petersburg, Florida, generating more than 100 Terabytes of data in the process. Herein, we describe a suite of open-source software tools we developed to manage the collection and analysis of these data, and present preliminary results on tortoise activity levels at this study site. The tools incorporate a convolutional neural network trained to detect gopher tortoises and to generate a draft video segmentation marking when tortoises are present. These tools allow a single human grader to review and refine the draft segmentations for a week’s worth of time-lapse recordings (11.5 hours of video if played back at standard speed) in under 3 hours.  This research demonstrates that the tools developed can facilitate future studies across research groups to assess key population features as well as to remotely monitor wildlife populations efficiently.

Large-scale Gopher Tortoise translocations are a widespread practice to remove tortoises from imminent dangers of habitat loss for human development. However, translocation for explicit conservation goals remains an infrequently-utilized and untested tool to conserve this at-risk species. Given the effects of density on tortoise movement and population viability, we conducted a conservation effort to increase the population density of a low-density tortoise population on a public property in southern Alabama. Efforts included consolidating the resident tortoises from a fire-suppressed landscape into a temporary enclosure located in a high-quality restored sandhill. We also headstarted two cohorts of hatchlings from the site for one and two years. In total, 100 resident tortoises were consolidated into the enclosure and 98 headstarted juvenile tortoises were released into the nearby area into both soft- and hard-release conditions. Using radiotelemtry of a sub-population of consolidated adults tracked for two seasons (before and after the enclosure was removed), we found that site fidelity of the adults was 69% in the area enclosed by the pen and 93% in the wider-managed site. Adult home range area was not significantly different between the years that adult tortoises were enclosed in the pen and the year after the pen was removed. A sub-population of two-year old headstarts was also radiotracked. Radiotracked headstarts had 100% site fidelity, regardless of release condition, and home ranges significantly decreased over the study period. Mortality was extremely low in all groups. We further discuss how this research may contribute to effective strategies for the demographic management of low-density tortoise populations, particularly in the species’ distributional periphery.