Gopher tortoise

The gopher tortoise is a keystone species that creates networks of underground burrows that are home to an additional 350 species, where 60 are vertebrates. Vertebrates have been shown to differ between habitat types and seasonally, but limited information is known about vertebrate associates in our region. This study was one of the first to investigate this in our region of south Florida. This study was designed to investigate factors that may affect the presence of vertebrates at gopher tortoise burrows. Camera data was collected to determine vertebrate presence and if specific vertebrate groups elicit a territorial response from the tortoise, while habitat vegetation surveys and weather data were collected to evaluate seasonality. Statistical analysis showed variation in vertebrate presence both seasonally and by habitat type. Few territorial interactions were observed overall. This study acts as a starting point to increase our understanding of local tortoise populations.

Gopher tortoise (Gopherus Polyphemus) burrows provide a unique microhabitat used by hundreds of vertebrate and invertebrate species. Prior to this study, limited information was available regarding burrow commensal species in southeast Florida, especially for invertebrate taxa. This study is an in-depth investigation of vertebrate and invertebrate gopher tortoise burrow commensals and is the first to document obligate invertebrate commensals (OIC) in this region. The objective was to test a variety of noninvasive methods effective for surveying commensals, compile an account of species dependent on gopher tortoise burrows in southeast Florida, accumulate information on threatened, endangered, and invasive species, add to the distributional information on OIC’s, and present information to land managers. Three pine flatwoods and three scrub habitats, with varying degrees of management were surveyed. Eighty-nine species were identified. This study was a substantial step toward documenting gopher tortoise burrow commensals in this region.

Gopher tortoises (Gopherus polyphemus) are keystone species mainly due to their burrow construction. Gopher tortoises can also impact the plants around them, but it is rarely quantifiable due to constraints in dispersal studies including time period and seasonality of fruit. The objective of this study was to measure the effect gut-passage has on a native Florida stone-pitted shrub, the cocoplum bush (Chrysobalanus icaco), as well as to attempt to model the relationship between the gopher tortoise and the plant using our unique field site. This study shows that gut-passage has a significant effect on the germination rate of the cocoplum, allowing it to germinate faster than control groups. This study also found that a model involving covariates relating to tortoise movement as a predictor for cocoplum intensity was favored over a homogeneous null model. We believe the pattern of plants is nonrandom and relates to the gopher tortoise’s seed dispersal.

Environmental parameters were quantified to develop a physiognomically-based system for describing and predicting gopher tortoise (Gopherus polyphemus) habitat on the Florida Atlantic University Nature Preserve. There were significant correlations among gopher tortoise densities and all physiognomic features except saw palmettos. The only feature with predictive usefulness was bare ground as indicated by a multiple regression. Burrows were regularly dispersed and the highest densities occurred in wet prairie associations. Tortoises located burrows in areas with less canopy and shrub cover but greater herbaceous cover and more extensive bare ground. This physiognomically-based system for predicting location of gopher tortoise habitats should prove useful in the relocation of displaced tortoises as required by the Florida Game and Fresh Water Fish Commission.

Upper Respiratory Tract Disease (URTD) is a highly contagious illness, caused by the bacterium Mycoplasma agassazii. URTD has affected the gopher tortoise population in the Abacoa Greenway, and is believed to have a high mortality rate. In this study, 18 samples of tortoise blood were collected from this location. Fifteen of the 18 samples were collected from previously tested individuals. Comparisons between the previously tested tortoises were made. According to this study there is no documented mortality rate with URTD in Abacoa. Results show that four tortoises have continued to test positive for the antibodies for several years, suggesting a chronic state of the disease. Four other tortoises have gone from positive results to negative results indicating that their immune systems' production of antibodies has tapered off, suggesting the ability to recover from the disease.

The gopher tortoise (Gopherus polyphemus) is endemic to the Southeast United States, where its populations are declining primarily due to habitat loss. Gopher tortoises prefer habitats with open sunny spots for nesting and basking. Fire is a normal element in gopher tortoise habitat, and when natural fires are suppressed, habitats may become too overgrown. To maintain the open spaces, some land managers use reduction mowing of vegetation. I studied gopher tortoises in the Abacoa Greenway reserve, established to protect the tortoises in a residential area of Jupiter, Florida, and I examined how reduction mowing influences tortoise activity. I evaluated the distribution of burrows throughout the study site by flagging the burrows both before and after extensive reduction mowing took place in the greenway. Statistical comparison between new burrows found within the interior as compared to the periphery both before and after the mowing reveal a significant relationship between both variables. These results suggest that the tortoises utilize newly mowed areas as preferred substrate for new burrows.

This study assesses the philosophical underpinnings of endangered species protections focused on gopher tortoises in Florida. From 1993-2007, gopher tortoises (Gopherus polyphemus) were listed in Florida as a species of special concern. Land developers wanting to build on their habitats could apply for an incidental take permit, paying a fee that allowed tortoises to be 'entombed' in their burrows to die a slow death. In 2007, when gopher tortoise status was up-losted to 'threatened', a new policy ended the incidental take permit program. This study compares policy guidelines of the 1991 and 2007 gopher tortoise management plans and explores cases that deal with incidental take controversies. I will apply perspectives from environmental philosophy to my analysis to understand how policies attempt to balance economic goals with a mandate to protect species in peril.

The gopher tortoise, Gopherus polyphemus, is a threatened species native to the southeastern United States. The breeding season of G. polyphemus is reportedly from April to June. However, out of season hatchlings in Jupiter, Florida, suggest that in South Florida, the very southernmost part of the gopher tortoise's range, the warmer climate allows a longer period of reproduction or a year-round breeding season. My research sought to find evidence for an extended breeding season and to collect fecundity data on the South Florida tortoises by capturing female tortoises and X-raying them at different times of the year to check for the presence of eggs. Although I found no conclusive proof of an extended breeding season, I present additional circumstantial evidence for it, as well as information regarding the fecundity of tortoises in the spring.