Mass mortality of Northern Map Turtles (&lt;em&gt;Graptemys geographica&lt;/em&gt;)

Catrysse, Jordan; Slavik, Emily; Choquette, Jonathan D.; Leifso, Ashley E.; Davy, Christina M.

doi:10.22621/cfn.v129i1.1671

Cited by 5 publications

(3 citation statements)

References 9 publications

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“…In some cases, the causes are mysterious (Sheppard , Catrysse et al. ). Many ecologists and conservationists believe that turtles are likely to have only a weak ability to compensate for perturbations and that recovery of turtle populations after declines will be extremely slow, if they occur at all (Brooks et al.…”

Section: Introductionmentioning

confidence: 99%

Post‐catastrophe patterns of abundance and survival reveal no evidence of population recovery in a long‐lived animal

2018

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Population catastrophes are widespread, unpredictable phenomena occurring in natural populations that have important, yet frequently underappreciated, consequences for persistence. As human impacts on ecosystems increase globally, the frequency of catastrophes is likely to rise as increasingly fragmented and depleted populations become more vulnerable. Species with slow life histories are expected to recover slowly from catastrophes because of their longer generation times, and assessing their population recovery requires data spanning long periods. We report results from a long‐term mark–recapture study of snapping turtles (Chelydra serpentina) in Algonquin Provincial Park, Ontario, that experienced a major mortality event from winter predation by river otters. We estimated abundance and survival of nesting females before, during, and 23 yr following the catastrophe. We built multistate mark–recapture models incorporating movement between sites, temporary emigration, and observation effects. We found that during the 3‐yr mortality event, abundance of nesting females declined by 39% overall, and by 49% at our focal nesting area. Apparent survivorship of nesting females during these three years fell from 0.94 before the mortality event to 0.76 at the focal site and 0.86 at adjacent nest sites. Survivorship over the following 23‐yr period averaged 0.972 and 0.940 at the two sampling areas. Despite high post‐catastrophe survivorship and connectivity with other populations, the population failed to recover, displaying consistently reduced abundances across 23 post‐catastrophe years. We discuss the relationship between life‐history attributes and the causes and consequences of local catastrophes and their conservation implications.

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Section: Introductionmentioning

confidence: 99%

Post‐catastrophe patterns of abundance and survival reveal no evidence of population recovery in a long‐lived animal

2018

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“…We also evaluated the effect of an event that temporarily increased adult mortality (e.g., poaching, winterkill, catastrophic environmental event) in the population after 30 years by decreasing adult survival rates for the first 2 years in our model by 1%, 10%, and 25%. We selected these morality rates and this timeframe because estimates of map turtle mortality due to poaching are limited but winterkills of northern map turtles can kill nearly 10% of known nesting females in a single season (Catrysse et al 2015) and catastrophic oil spill events can decrease the number of females in a single population by nearly 25% in the first few years following the spill (Otten et al 2022). Thus, rare and isolated events can have substantial influences on population trends for decades following the event itself.…”

Section: Elasticity and Sensitivity Analysismentioning

confidence: 99%

Bigger is better: age class‐specific survival rates in long‐lived turtles increase with size

Otten,

Refsnider

2024

J Wildl Manag

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Vital rates for small, non‐breeding individuals are important components of population dynamics for many species, but often individuals of these sizes are difficult to locate, capture, and track. As such, biologists frequently lack reliable estimates of juvenile survival because sample sizes and recapture rates for this life stage are low. Long‐lived animals often take many years to reach sexual maturity and spend much of this time in the smaller size classes, making them sensitive to changes in survival rates. We estimated the survival rates of all size classes for the northern map turtle (Graptemys geographica) using a mark‐recapture dataset with >3,500 captures from 2019–2021 and 210 nests from 2018–2021. As turtle size increased, annual survival probability increased regardless of sex. Estimated annual survival probability for turtles >18 cm long (i.e., adult females >15 years) was about 0.95, over 4 times higher than turtles that were 3 cm long (i.e., hatchlings <1 year; 0.22 annual survival probability). Although we did not observe a difference in survival probability between sexes of any size class, adult females are nearly twice the size of adult males, leading to an increased annual survival probability for females of 0.95, compared to 0.80 for males. Changes in adult survival had the greatest influence on population estimates over time, with temporary decreases, such as those due to poaching or an environmental disaster, potentially leading to unrecoverable decreases in the overall population size. Our study provides detailed survival rates for all size classes in a long‐lived turtle, which are necessary to assess population stability and can be used to determine the most effective conservation or management practices.

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“…Fishing nets set near such communal sites could result in even higher by-catch and mortality. Catrysse et al (2015) reported that during a four-week period the bodies of 35 adult females were found stranded on the north shore of Lake Erie in Ontario. Although the cause of mortality could not be determined, fisheries by-catch could not be excluded as a potential cause.…”

Section: 8mentioning

confidence: 99%

Graptemys geographica (LeSueur 1817) – Northern Map Turtle, Common Map Turtle

Vogt¹,

Bulté²,

Iverson³

2018

Chelonian Research Monographs

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The Northern Map Turtle, Graptemys geographica (Family Emydidae), is a mediumsized sexually dimorphic freshwater turtle species (female carapace length to 292 mm, males to 160 mm) and the sister taxon to all other map turtle species. It is often common in rivers and lakes within its North American range. The turtles make extensive movements within their habitats for nesting, basking, and feeding. Mating occurs in fall and spring; hibernation lasts from October to mid-April in northern regions, and most hatchlings overwinter in the nest. Northern Map Turtles are primarily carnivorous, feeding predominately on snails, bivalves (including invasive dreisennid mussels), and aquatic insect larvae. Two to three clutches of 6 to 20 eggs are laid each year between late May and mid-July. Because males mature after about 4 years and females require about 10 years, adult sex ratios are often skewed towards males. Sex ratios are also influenced by nest temperatures, with warmer nests producing females and cool nests producing males. Direct and indirect human activities, including fisheries by-catch mortality, appear to be responsible for some population declines of this species in some regions, but G. geographica is not at this time considered Threatened.distRiBution. -Canada, USA. Southwestern Quebec and southeastern Ontario to central Alabama, northern Louisiana, west to central Minnesota and eastern Kansas and Arkansas, with scattered isolated populations in the northeastern USA in Vermont, New York, New Jersey, and Pennsylvania.

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Mass mortality of Northern Map Turtles (<em>Graptemys geographica</em>)

Cited by 5 publications

References 9 publications

Post‐catastrophe patterns of abundance and survival reveal no evidence of population recovery in a long‐lived animal

Post‐catastrophe patterns of abundance and survival reveal no evidence of population recovery in a long‐lived animal

Bigger is better: age class‐specific survival rates in long‐lived turtles increase with size

Graptemys geographica (LeSueur 1817) – Northern Map Turtle, Common Map Turtle

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