Diet of Diamondback Terrapins (<i>Malaclemys terrapin</i>) in Subtropical Mangrove Habitats in South Florida

Denton, Mathew J.; Hart, Kristen M.; Demopoulos, Amanda W.J.; Oleinik, Anton E.; Baldwin, John W.

doi:10.2744/ccb-1187.1

Cited by 9 publications

(11 citation statements)

References 14 publications

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“…The presence of seagrass may be another important covariate we did not consider as the significance of abundant terrapin prey items within seagrass beds has been underestimated (Tulipani 2013, Tulipani andLipcius 2014). Terrapins are not dietary specialists and feed on a variety of benthic organisms and not just mollusks associated with salt marsh vegetation (Butler et al 2012, Denton et al 2016). Our results suggested that terrapin densities decreased with distance to mangroves, but the bs slightly overlapped zero.…”

Section: Discussionmentioning

confidence: 99%

Sampling rare and elusive species: Florida east coast diamondback terrapin population abundance

et al. 2019

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The Florida east coast terrapin (Malaclemys terrapin tequesta) is a rare and potentially endangered species that is difficult to survey because of poor detection probability and a patchy distribution. Like many rare species sampling programs, we apply a density and multistate occupancy sampling approach that considered the impacts of imperfect detection. We separated the detection process into availability of the animal within the sampling area (e.g., coming to surface) and perceptibility (actually seeing it). Our study employed a density estimation approach originally developed for birds, which combined time to detection and distance sampling within a Bayesian N-mixture model. Our study also estimated two abundance occupancy states (few and many terrapins). We were able to estimate large differences in terrapin densities between sites through functions of site-specific environmental covariates (water depth, distance to mangrove, and distance to land). The detection probability was poor (0.28) for the few terrapin occupancy state, but was much greater for many (0.75). The time to detection and distance-sampling approach for this aquatic animal should be useful for other aquatic organisms that regularly surface. Terrapins were generally available to be sighted within four minutes but detection declined rapidly to a low probability of terrapin detection >30 m. The approach of estimating density as a function of habitat covariates to identify habitat associations can provide an effective method that combined with adaptive sampling should be useful to investigate the distribution of terrapins in open water.

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Section: Discussionmentioning

confidence: 99%

Sampling rare and elusive species: Florida east coast diamondback terrapin population abundance

et al. 2019

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“…This species is dimorphic in body size with females being larger than males and having wider heads (Tucker, Fitzsimmons & Whitfield Gibbons, 1995). Moreover, this species is considered to be durophagous with both sexes consuming a variety of gastropods, crabs and other hard-shelled prey (Tucker et al, 1995;Butler, Heinrich & Mitchell, 2012;Denton et al, 2016;Outerbridge et al, 2017). Sexual differences in diet have been demonstrated for this species (Tucker et al, 1995;Butler et al, 2012) and it has been suggested that resource use may be limited by snail shell strength in diamondback terrapins (Tucker et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

Sexual dimorphism, bite force and diet in the diamondback terrapin

2017

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Sexual dimorphism in head size and shape has been documented in many animals and is often thought to be related to the consumption of different prey in males and females thus reducing competition between the two sexes. However, for this to be true, the difference in head size and shape should be associated with a difference in performance allowing one sex to exploit different prey resources. In many durophagous turtle species, females are bigger than males and have bigger heads for a given size. Here, we test whether the observed dimorphism in head size and shape in the durophagous Malaclemys terrapin is reflected in differences in bite force. Furthermore, we measure the forces needed to crush different prey items in order to evaluate whether the observed bite force dimorphism allows access to different dietary resources in females. Finally, we compare head size and shape and bite force between the durophagous M. terrapin and a generalist (Trachemys scripta). Our results show that females of M. terrapin have higher bite forces than males in line with their bigger heads relative to their body size. Moreover, the higher bite forces in females allow them to eat larger as well as different types of snails resulting in differences in diet. Finally, our results show that both sexes of M. terrapin have bigger heads and bite forces for their body size compared to the generalist T. scripta, even as juveniles. Moreover, M. terrapin bite harder even when taking into account differences in head size, suggesting intrinsic differences in the jaw musculature in durophagous species.

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“…Thus, investigations examining diet variation in natural populations are necessary to understand the plasticity of food webs. Dietary habits of reptile taxa have often been investigated by examining stomach or fecal contents (Erazmus 2012;Rosenblatt et al 2015;Denton et al 2016;Nifong 2016). An important underlying question in these studies is if using these "snap-shot" techniques represents long-term diet trends.…”

Section: Introductionmentioning

confidence: 99%

“…Previous terrapin diet studies utilized fecal analysis, stomach flushing, or dissection (Tucker et al 1995;Spivey 1998;Butler et al 2012;Tulipani 2013;Denton et al 2015Denton et al , 2016Alleman and Guillen 2017). Several of these studies have shown that both males and immature females of a similar size had similar diets, but both groups had diets that differed from larger mature females.…”

Section: Introductionmentioning

confidence: 99%

“…The previous examples of seed retention illustrate the passage time of indigestible materials through the terrapin digestion system; thus, fecal remains may represent what an individual has eaten only within a few days. Previous investigations into the diets of south Florida terrapin populations (Baldwin et al 2005;Denton et al 2015Denton et al , 2016 have been limited to these methods, thus only providing a record of short-term diet. Currently, we lack the information required to distinguish between natural temporal diet shifts and changes due to shifts in available resources.…”

Section: Introductionmentioning

confidence: 99%

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Stable Isotope Analysis Enhances Our Understanding of Diamondback Terrapin (Malaclemys terrapin) Foraging Ecology

Denton

Demopoulos

Baldwin

et al. 2018

Estuaries and Coasts

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Dietary studies on generalist predators may provide valuable information on spatial or temporal changes in the structure of ecological communities. We initiated this study to provide baseline data and determine the utility of stable isotope analysis (SIA) to evaluate the foraging strategies of an opportunistic reptilian predator, the diamondback terrapin (Malaclemys terrapin), which specializes in salt marshes and mangrove estuaries along the Atlantic and Gulf coasts. We evaluated stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope values of multiple tissues from terrapins inhabiting mainland and island mangrove habitats in south Florida and potential food sources to examine spatial and temporal variations in terrapin resource use. We fit linear regression models to determine the best predictors of isotopic values for both terrapins and their prey, and Stable Isotope Bayesian Ellipses in R (SIBER) analysis to examine terrapin isotopic niche space and overlap between groups. We identified differences in terrapin isotopic δ 13 C and δ 15 N values among all sites. Blood and scute tissues revealed different isotopic compositions and niche overlap between sites, suggesting diets or foraging locations may change over time, and amount of variation is site specific. Niche overlap between size classes was larger for blood (short term) versus scute (long term), suggesting greater variability in food habits or resource isotopes over the long term versus short term. These results demonstrate the usefulness of SIA in examining the spatial and temporal variability in diamondback terrapin resource use within estuary systems and further define their niche within these dynamic food webs.

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Diet of Diamondback Terrapins (Malaclemys terrapin) in Subtropical Mangrove Habitats in South Florida

Cited by 9 publications

References 14 publications

Sampling rare and elusive species: Florida east coast diamondback terrapin population abundance

Sampling rare and elusive species: Florida east coast diamondback terrapin population abundance

Sexual dimorphism, bite force and diet in the diamondback terrapin

Stable Isotope Analysis Enhances Our Understanding of Diamondback Terrapin (Malaclemys terrapin) Foraging Ecology

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