Gopher Tortoise (Gopherus polyphemus) Densities in Coastal Scrub and Slash Pine Flatwoods in Florida

Breininger, David R.; Schmalzer, Paul A.; Hinkle, C. Ross

doi:10.2307/1564681

Cited by 25 publications

(20 citation statements)

References 5 publications

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“…The negative association with other land cover may be a result of the proliferation of woody scrub and invasive plants such as saw‐palmetto ( Serenoa repens ), cabbage palm ( Sabal palmetto ), sea grape, and Brazilian pepper throughout the area (Diemer , Menges ). Our results agree with those of Breininger et al (), who reported tortoise density at KSC to be positively associated with an increase in areas that were disturbed and supported herbaceous vegetation. Lau and Dodd () also reported a significant, positive relationship between herbaceous cover and coastal tortoise burrow density.…”

Section: Discussionsupporting

confidence: 93%

“…As we predicted, estimates of gopher tortoise density generated by our top model were significantly higher for the constructed dunes versus natural dues at MINWR, and the overall tortoise density for constructed dunes was similar to previously reported values for natural coastal tortoise populations elsewhere (0.64–3.05 burrows/ha, Lau and Dodd []; 0–30.7 individuals/ha, Breininger et al []). We found the first burrow on the 2014 dune approximately 3 months post‐construction, with a rapid increase in burrows prior to the first transect being completed in the area.…”

Section: Discussionsupporting

confidence: 86%

“…Additionally, improper translocations contribute to population declines (Berry and Aresco ). Prior studies on coastal populations of gopher tortoises (Breininger et al , Lau and Dodd ) reported that density was positively associated with ruderal and open herbaceous cover as a source of food, whereas coverage by woody vegetation was negatively associated with density. By evaluating colonization rates and local population sizes on constructed dunes, we sought to determine if gopher tortoise density along constructed dunes was similar to surrounding natural dunes, and if constructed dunes would function for a managed retreat as sea‐levels rise.…”

mentioning

confidence: 96%

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Adapting coastal management to climate change: Mitigating our shrinking shorelines

et al. 2017

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Sea‐level rise due to climate change is a major threat to coastal ecosystems worldwide. Current management to reduce beach erosion often focuses on protecting human structures and research on effects on wildlife is lacking. Using a combination of hierarchical models and generalized linear models, we evaluated how the gopher tortoise (Gopherus polyphemus) colonized constructed dunes along coastal scrub at the Merritt Island National Wildlife Refuge, central Florida, USA. Over 2 years, we surveyed tortoise populations along natural dunes and 2 constructed dunes (completed in 2012 and in 2014) and estimated tortoise density each summer and winter. Our models indicated that tortoise density along the 2014 dune was comparable to that of natural dunes (truex¯ = 0–8 tortoises/ha), and density peaked at a mean of 21 tortoises/ha along the 2012 constructed dune. Gopher tortoises rapidly colonized constructed dunes, and dune construction may represent effective management against habitat loss for this species. © 2017 The Wildlife Society.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionsupporting

confidence: 86%

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confidence: 96%

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Adapting coastal management to climate change: Mitigating our shrinking shorelines

et al. 2017

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“…Relative importance of burrow site selection factors and parameter coefficient estimates (b) for gopher tortoises (n ¼ 198) in the coastal sand dunes of GTMNERR, ranked by the sum of the model weight. of herbaceous cover (Breininger, Schmalzer, and Hinkle, 1994). The results of this study suggested that the amount of herbaceous vegetation cover could be a visual cue that gopher tortoises use to select suitable burrow sites.…”

Section: Discussionmentioning

confidence: 72%

Multiscale Burrow Site Selection of Gopher Tortoises (Gopherus polyphemus) in Coastal Sand Dune Habitat

Lau

Dodd

2015

Journal of Coastal Research

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Lau, A. and Dodd, C.K., Jr., 2015. Multiscale burrow site selection of gopher tortoises (Gopherus polyphemus) in coastal sand dune habitat. Journal of Coastal Research, 31(2), 305-314. Coconut Creek (Florida), ISSN 0749-0208.The gopher tortoise (Gopherus polyphemus) is a keystone species in upland sandhill ecosystems of the SE United States, and its habitat requirements have been well documented. Few studies have been conducted on populations that occur in coastal sand dunes. Because of close proximately to the ocean and highly fragmented linear habitat, coastal populations of gopher tortoises are affected by unique landscape factors that are not observed in upland contiguous populations. In this study, burrow site selection of gopher tortoises in a coastal sand dune site was quantitatively modeled. Significant biological, environmental, and anthropogenic factors that may influence burrow site selection at fine and coarse spatial scales were identified. Land cover type, distance to edge, soil resistance, percentage of herbaceous cover, slope angle, and number of tortoise burrows have significant influences on burrow site selection probability. Factors that influence burrow locations in coastal populations thus might differ in importance from those that influence burrow locations in more spatially contiguous upland populations. Our results indicate that coastal gopher tortoise populations require sitespecific management that focuses on the limited availability of optimal burrow construction sites.

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“…At least 60-80 observations are recommended to model the detection function reliably (Buckland et al 2001). Gopher tortoises can occur in naturally low densities in suboptimal habitat (Breininger et al 1994;Castellón et al 2012;Legleu 2012) or may persist at low densities because of past exploitation for food or inadequate habitat management (Hermann et al 2002). Surveys of low-density populations require considerable effort in terms of total transect length, and small sample size can reduce precision (Smith et al 2009;Castellón et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Techniques for Estimating the Size of Low-Density Gopher Tortoise Populations

Stober

Prieto-Gonzalez

Smith

et al. 2017

Journal of Fish and Wildlife Management

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Gopher tortoises (Gopherus polyphemus) are candidates for range-wide listing as threatened under the U.S. Endangered Species Act. Reliable population estimates are important to inform policy and management for recovery of the species. Line transect distance sampling has been adopted as the preferred method to estimate population size. However, when tortoise density is low, it can be challenging to obtain enough tortoise observations to reliably estimate the probability of detection, a vital component of the method. We suggest a modification to the method based on counting usable tortoise burrows (more abundant than tortoises) and separately accounting for the proportion of burrows occupied by tortoises. The increased sample size of burrows can outweigh the additional uncertainty induced by the need to account for the proportion of burrows occupied. We demonstrate the method using surveys conducted within a 13,118-ha portion of the Gopher Tortoise Habitat Management Unit at Fort Gordon Army Installation, Georgia. We used a systematic random design to obtain more precise estimates, using a newly developed systematic variance estimator. Individual transects had a spatially efficient design (pseudocircuits), which greatly improved sampling efficiency on this large site. Estimated burrow density was 0.091 6 0.011 burrows/ha (CV ¼ 12.6%, 95% CI ¼ 0.071-0.116), with 25% of burrows occupied by a tortoise (CV ¼ 14.4%), yielding a tortoise density of 0.023 6 0.004 tortoise/ha (CV ¼ 19.0%, 95% CI ¼ 0.016-0.033) and a population estimate of 297 tortoises (95% CI ¼ 210-433). These techniques are applicable to other studies and species. Surveying burrows or nests, rather than animals, can produce more reliable estimates when it leads to a significantly larger sample of detections and when the occupancy status can reliably be ascertained. Systematic line transect survey designs give better precision and are practical to implement and analyze.

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Gopher Tortoise (Gopherus polyphemus) Densities in Coastal Scrub and Slash Pine Flatwoods in Florida

Cited by 25 publications

References 5 publications

Adapting coastal management to climate change: Mitigating our shrinking shorelines

Adapting coastal management to climate change: Mitigating our shrinking shorelines

Multiscale Burrow Site Selection of Gopher Tortoises (Gopherus polyphemus) in Coastal Sand Dune Habitat

Techniques for Estimating the Size of Low-Density Gopher Tortoise Populations

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