Workshop on the Ecology, Status, and Management of the Gopher Tortoise (Gopherus polyphemus), Joseph W. Jones Ecological Research Center, 16–17 January 2003: Final Results and Recommendations

From 16 to 17 January 2003, 30 invitees from 6 states gathered at the Joseph W. Jones Ecological Research Center in Georgia for a workshop to discuss the status, ecology, and conservation of the gopher tortoise (Gopherus polyphemus). The impetus for this workshop was continuing reports of declining tortoise populations despite federal and state legal protection throughout the range. The gopher tortoise is federally listed as threatened in Louisiana, Mississippi, and west of the Tombigbee and Mobile Rivers in Alabama, and receives varying degrees of state protection in eastern Alabama, Florida, Georgia, and South Carolina.

In addition to the exchange of data on tortoise biology and status, the workshop was designed to identify research needs that may lead to more effective conservation of gopher tortoise populations rangewide. This objective was accomplished by a survey of participants' perception of the status, threats, and research needs for tortoise populations, and by an assessment of the state of knowledge of tortoise populations in protected areas. The 30 attendees as well as numerous state and regional biologists provided the data. We summarize the major findings and recommendations that emerged from the workshop.

Methods

Prior to the workshop, we asked representatives from each state to provide an overview of the legal and biological status of the gopher tortoise in their state. This information included state-level protection and management policies pertaining to the gopher tortoise, an evaluation of population trends, and major threats to the species in each state. We also asked representatives to summarize information about tortoise populations in protected areas. We chose to restrict our efforts to protected areas (state lands, federal lands, private reserves) because we felt these sites would have the most current and readily available data. We specifically requested information on population size (and the source of the data and methods by which the estimate was derived), percent juveniles, habitat management practices, and threats to populations. We also requested Geographic Information Systems (GIS) maps of locations of the protected areas. During the workshop, all attendees were asked to respond to a questionnaire on the status and threats to gopher tortoises rangewide. The workshop agenda also included a discussion of critical research needs.

Results

Although only 21 attendees returned questionnaires, we considered the results noteworthy because these individuals were a cross section of experts from the entire range of the species and because they represented academia, state and federal agencies, and nongovernmental organizations. The key results of the questionnaire are presented here.

An overwhelming majority of respondents (85.7%, n = 18) felt that gopher tortoises were declining; 4.7% said that populations were stable; and 4.7% said that populations were increasing. Reflecting this assessment, 76.2% of respondents (n =16) said that tortoise populations would decline to the point that additional legal protection would be warranted in the next 50 years. Furthermore, 43.3% of 18 respondents felt that local or regional extinction was likely within a 50-year period.

Respondents were asked to rank the major threats to gopher tortoises on a scale of 1 to 6, where 1 was the greatest threat. The following is a summary of the rankings of all 21 respondents, in order of perceived importance:

1. Habitat destruction (mean rank = 1.66, range = 1–3)

2. Lack of habitat management (e.g., fire suppression; mean rank = 1.73, range = 1–3)

3. Invasive species (mean rank = 3.76, range = 1–5)

4. Upper respiratory tract disease (mean rank = 3.88, range = 2–5

5. Collecting/poaching (mean rank = 4.13, range = 3–5)

6. Other (road impacts, habitat fragmentation, rattlesnake roundups, small population sizes)

Respondents were asked to divide the research needs for gopher tortoises into 3 groups: 1) aspects that are known well enough to make generalizations (“Things we know”); 2) aspects known reasonably well, but where more data are needed (“Things we think we know”); and 3) poorly known aspects, where more data are needed badly (“Things we don't know”). After considerable discussion, the group reached a consensus, as summarized in Table 1. The group did not rank topics within groups, but there was strong consensus that the topics in the last category (i.e., “Things we don't know) urgently need more study and warrant special consideration for funding by federal and state agencies and private conservation groups.

Table 1. Legal status, population trends, and threats to gopher tortoise populations rangewide.

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Table 1. Extended.

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According to Natural Heritage Program rank designations (Stein et al. 2000), which are biological rather than legal designations, the gopher tortoise is Vulnerable throughout its range (Global Rank = G3; Table 2). The degree of imperilment varies among states: the gopher tortoise is Vulnerable (State Rank = S3) in Alabama, Georgia, and Florida; Imperiled (S2) in Mississippi; and Critically Imperiled (S1) in Louisiana and South Carolina. In addition, state representatives considered gopher tortoise populations to be declining in at least 3 states (Florida, Louisiana, South Carolina). Population trends are unknown for Alabama.

Table 2. Summary of how the attendees at the Gopher Tortoise Status Workshop divided research needs for gopher tortoises into 3 distinct categories. Within categories, research topics are listed in unranked alphabetical order. See text for details of categories.

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Although the gopher tortoise is federally listed in only the western portion of its range, each state in the species' range legally recognizes the gopher tortoise as a Species of Concern, State-Threatened, or State-Endangered. However, in practice, the level of protection that these legal designations actually confer to the species varies dramatically among states and, in some cases, from the intended goal. For example, several states lack protection measures against incidental take (Table 2). In addition, some current state management policies (i.e., relocation practices in Florida) are ranked as one of the primary threats to the species in that state.

State representatives provided data for 280 tortoise populations on protected areas in Florida, 54 in Georgia, 11 in Alabama, 8 in Mississippi, 3 in South Carolina, and 3 in Louisiana. A range of methods was used to derive population estimates, including counts based on burrow camera surveys, burrow counts with or without application of a correction factor, GIS-based population estimates, and detailed long-term studies of individual populations. In addition, state representatives considered gopher tortoise populations to be declining, or presumed declining, in each of the 6 states within the range of the tortoise.

The populations were categorized by size and mapped to demonstrate the distribution of populations on protected areas rangewide (Fig. 1). Florida had the most comprehensive data for state and federal lands, as a result of a recent population viability analysis performed by the Florida Fish and Wildlife Conservation Commission (P.S. Miller, unpubl. data, 2001); however, the data used for the analysis were nearly 10 years old. The largest populations (> 10,000 tortoises) on protected areas were Apalachicola National Forest, Withlacoochee State Forest, Ocala National Forest, and Merritt Island National Wildlife Refuge. Mississippi also had fairly detailed data for populations on Camp Shelby Training Site and Desoto National Forest, which fall within the federally listed portion of the range. These sites harbor the largest populations of tortoises (> 1000 individuals) in the state. Although tortoises are widely distributed in southern Georgia, there are few protected areas with tortoise populations, and little is known of their status on existing protected areas. Only 3 protected areas in Georgia have populations greater than 1000 individuals. Although Alabama comprises ca. 14% of the species' range, only 11 protected areas have tortoise populations, and only Conecuh National Forest and Fort Rucker have large populations (> 1000 tortoises). Of the 3 protected areas with tortoise populations in South Carolina (Tillman Sand Ridge Heritage Preserve, Aiken Gopher Tortoise Heritage Preserve, and a reintroduced population at the Savannah River Site), Tillman Sand Ridge Heritage Preserve supports the largest population (< 500 tortoises). Only 1 naturally occurring population exists in Louisiana (Ben's Creek Wildlife Management Area; < 250 tortoises).

Across all states, only limited data were available on the percent of juveniles in individual populations (a possible indication of recruitment). Recent studies at Camp Shelby training site in Mississippi have indicated that, on an annual basis, recruitment in tortoise populations can be quite low (Epperson and Heise 2003). Although adult survivorship is probably the most critical demographic variable for gopher tortoises, the lack of information on juvenile survivorship across the range may be cause for concern.

The major threat to protected populations identified by state representatives was fire suppression or lack of growing season fires. Other threats included impacts of timber management (e.g., site preparation and high basal area), predation (by non-native and native subsidized predators), road mortality, disease, release of waif tortoises, and habitat degradation due to invasive plants. In addition, many populations (41%, n =145) on protected areas were considered too small (< 100 individuals) to be viable over the long term.

Recommendations

The group considered the pros and cons of petitioning for federal status for the gopher tortoise rangewide, but had concerns about whether this action is biologically defensible and if it might have negative repercussions. In addition, many in the group felt that federal listing has not conferred adequate protection for western populations already listed. Thus, the group did not support a motion to list the remaining populations as Threatened at this time. The group did, however, support a motion to pursue a Candidate Conservation Agreement with Assurances (CCAA) within the nonlisted portion of the range (US Fish and Wildlife Service 2003). CCAAs are formal agreements between the US Fish and Wildlife Service and private entities that address the conservation needs of proposed or candidate species, or species likely to become candidate species in the near future. Under a CCAA, federal funds may be available for research and monitoring activities that contribute to the elimination of the need to list the target species.

The intended use of the data on population status in protected areas generated for the workshop was to aid in identifying areas most likely to have stable, viable populations of gopher tortoises and to determine whether enough populations are protected to ensure the long-term survival of the species. It is clear that, at this time, we lack the demographic data to answer these questions. No comprehensive rangewide surveys have been conducted since Auffenberg and Franz in 1982 (but see Hermann et al. 2002). We also lack data on the amount of suitable tortoise habitat on protected areas, and all workshop participants shared the concern that fire suppression and lack of growing season fires may be causing a decline in tortoise populations on these lands. While tortoise populations still exist on most protected areas in Florida, we have no current data on population trends. Additionally, large gaps exist in the distribution of protected areas with tortoise populations in Georgia, Alabama, and Mississippi. Emerging technology such as GIS may aid in large-scale assessments, but survey data are still needed to calibrate the models (McCoy et al. 2002).

Given the uncertain status and gaps in the distribution of tortoise populations in protected areas, the group recognized that there is an urgent need for better surveys of tortoise populations on private lands. These populations are likely very important to conservation of the species (Hermann et al. 2002), and obtaining conservation easements on these lands is a priority. Further, a major effort is needed to identify key private lands for acquisition and management, as well as key partners for acquiring and managing these lands.

The group adopted a motion to establish a long-term monitoring/research network patterned after the Long Term Ecological Research (LTER) network model. The LTER network is a collaborative effort involving scientists and students investigating ecological processes over long temporal and broad spatial scales. We propose to establish a network of sites across the gopher tortoise's range to monitor populations over the long term, using standard methods that will build upon and complement work already in progress. The research priorities identified in the survey (Table 1) should be used to establish priorities for funding and for future research projects. The mechanism to establish this network is currently being investigated.