Habitat Utilization by the Turtle, Graptemys geographica, along a River

Pluto, Thomas G.; Bellis, Edward D.

doi:10.2307/1564121

Cited by 54 publications

(41 citation statements)

References 10 publications

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“…Roosenberg (1991) suggested that adult female diamondback terrapins are unable to escape oncoming boats as fast as males and small females because of their larger body size. However, swimming speed is an unsatisfactory explanation for the bias in traumatic injuries because female northern map turtles swim faster than males (Pluto and Bellis, 1986). Alternatively, it was found that both adult and juvenile females bask more at the surface of the water than males ( Figure 5).…”

Section: Discussionmentioning

confidence: 99%

“…Many species of river turtles with pronounced sexual size dimorphism exhibit marked intersexual differences in spatial ecology (Pluto and Bellis, 1986;Jones, 1996;Bodie and Semlitsch, 2000;Lindeman, 2003;Carrie`re et al, in press). Intersexual differences in spatial ecology are only present at the SLINP site (Carrie`re et al, in press), but these differences may nonetheless explain, at least partly, the bias in propeller injuries.…”

Section: Discussionmentioning

confidence: 99%

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Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica)

Bulté

Carrière

Blouin‐Demers

2009

Aquatic Conservation

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ABSTRACT1. Recreational power boating is growing in popularity in North America. This activity is known to have lethal and sub-lethal effects on aquatic wildlife and freshwater turtles may be particularly sensitive to this activity.2. This study reports on patterns of traumatic injuries inflicted by powerboat propellers to northern map turtles (Graptemys geographica) from two sites differing in boat traffic intensity in Ontario, Canada.3. The relative vulnerability of turtles was assessed, in light of seasonal patterns in boat traffic, as a function of sex-and age-specific movement patterns, habitat use, and basking behaviour obtained by radio-telemetry. Population viability analyses (PVA) were also conducted to evaluate the potential demographic consequences of mortality induced by powerboats.4. The prevalence of propeller injuries was two to nine times higher in adult females than in adult males and juvenile females. Patterns of movement, habitat use, and aquatic basking indicated that adult females are more exposed to collisions with boats. PVA showed that boat-induced mortality in adult females could lead to rapid population extinction if the risk of mortality when hit by a boat is greater than 10%.5. The results of this study showed that recreational power boating is a serious threat to northern map turtles, even under moderate boat traffic. The need to adopt measures restricting boat traffic in areas important to turtles is discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica)

Bulté

Carrière

Blouin‐Demers

2009

Aquatic Conservation

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“…Competition for space may occur among conspecific or heterospecific turtles if basking substrates are limiting (Bury and Wolfheim 1973;Auth 1975;Bury et al 1979;Pluto and Bellis 1986;Lovich 1988;Lindeman 1999). In such situations, body size may play an important role in determining the outcome of the competitive interaction (Bury and Wolfheim 1973;Auth 1975;Lindeman 1999).…”

Section: Introductionmentioning

confidence: 99%

Competitive interactions during basking between native and invasive freshwater turtle species

2009

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The red-eared slider (Trachemys scripta elegans) is currently introduced in many Mediterranean countries, where it behaves as an invasive species that competes and displaces native populations of the endangered Spanish terrapin (Mauremys leprosa). However, the nature of competitive interactions is relatively unknown. During basking activity, factors like greater body size or pre-existing behavioral adaptations to an original habitat with higher levels of interspecific competition might confer competitive advantages to introduced T. scripta with respect to native terrapins. We hypothesized that competition for basking places with the introduced T. scripta might negatively affect the efficiency of basking and thermoregulation of the native Spanish terrapin. We experimentally analyzed the basking activity of T. scripta and M. leprosa under occasional and long-term situations of intra-and inter-specific competition. Native M. leprosa subjected to interspecific competition reduced their basking activity, basked for shorter periods than T. scripta, and avoided basking stacked with the exotic turtles. These results suggested the displacement from the basking sites of the native terrapin by the introduced T. scripta. The decreased basking activity of native M. leprosa when competing directly for basking places with introduced sliders may lead native terrapins to a loss in the efficiency of physiological functions related to ineffective thermoregulation, such as digestion or locomotor performance, thus favoring the expansion of the invasive species.

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“…In the control habitat, the sex ratio tended towards more adult males, whereas in the fragmented habitat the skew was towards adult females and juveniles. Slightly male-biased sex ratios are reported as the norm in most populations of Northern Map Turtles (Gordon and MacCulloch 1980;Vogt 1980;Pluto and Bellis 1986;DonnerWright et al 1999;Conner et al 2005), although a female bias has been noted in three Canadian studies (Barrett Beehler 2007;Browne and Hecnar 2007;Carrière 2007).…”

Section: Sex Ratiosmentioning

confidence: 99%

“…One possible explanation for the difference in body sizes of turtles between fragmented and control sites may be related to habitat changes resulting from fragmentation, specifically the reduction in vegetated shallow-water habitat. Pluto and Bellis (1986) suggested that juvenile and male Map Turtles use different microhabitats than adult females. They found that turtles with a CL >12.5 cm were most often found in deeper areas of a river, whereas smaller turtles frequented shallower water habitats (Pluto and Bellis 1986).…”

Section: Body Size and Growth Ratesmentioning

confidence: 99%

Demographic differences among populations of Northern Map Turtles (Graptemys geographica) in intact and fragmented sites

2009

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Habitat fragmentation is a leading cause of reptile declines worldwide. We examined demographic differences between populations of Northern Map Turtles, Graptemys geographica (Le Sueur, 1817), inhabiting intact and fragmented sites along the Trent-Severn Waterway (TSW) in Ontario over two field seasons. We examined population densities, sex ratios, body size, and growth rates in two control sites and two fragmented sites (where the waterway is disrupted by dams). We predicted that population density would be higher in control sites, and that sex ratios would differ among sites. Abundance was greater than expected, but densities could not be compared owing to a lack of recaptures. Sex ratios in control sites were slightly male-biased and were significantly female-biased in fragmented sites. Turtles in fragmented habitats were significantly smaller than those in control habitats. Estimated growth rates of juveniles and males were significantly reduced in fragmented populations compared with controls. We hypothesize that habitat alterations in fragmented sites are differentially affecting demographic classes because of the intersexual niche divergence observed in Map Turtles. We emphasize the need for further research to examine the interactions between habitat alteration and invasive species and the effects they are having on Northern Map Turtle populations.Résumé : La fragmentation des habitats est une des causes principales du déclin des reptiles à l'échelle planétaire. Nous examinons les différences démographiques entre des populations de tortues géographiques boréales, Graptemys geographica (Le Sueur, 1817) habitant des sites intacts et fragmentés du réseau fluvial Trent-Severn (TSW) en Ontario au cours de deux saisons de terrain. Nous mesurons les densités de population, les rapports des sexes, les tailles corporelles et les taux de croissance dans deux sites témoins et deux sites fragmentés (dans lesquels le cours est perturbé par des barrages). Nous avons prédit que la densité de la population serait plus grande aux sites témoins et que le rapport des sexes différerait d'un site à l'autre. L'abondance était plus grande que prévu, mais les densités n'ont pu être comparées par manque de recaptures. Les rapports des sexes favorisaient légèrement les mâles dans les sites témoins et les femelles dans les sites fragmentés. Les tortues dans les sites fragmentés étaient significativement plus petites que dans les habitats témoins. Les taux de croissance estimés des jeunes et des mâles étaient significativement réduits dans les populations fragmentées, par rapport aux populations témoins. Nous émettons l'hypothèse selon laquelle les modifications des habitats dans les sites fragmentés affectent de manière différentielle les diverses classes démographiques à cause de la divergence de niche observée entre les sexes chez les tortues géographiques. Nous soulignons la nécessité de recherches additionnelles pour examiner les interactions entre les modifications des habitats et les espèces envahissantes et les effets qu'ell...

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Habitat Utilization by the Turtle, Graptemys geographica, along a River

Cited by 54 publications

References 10 publications

Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica)

Impact of recreational power boating on two populations of northern map turtles (Graptemys geographica)

Competitive interactions during basking between native and invasive freshwater turtle species

Demographic differences among populations of Northern Map Turtles (Graptemys geographica) in intact and fragmented sites

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