Hatching Success and Predation of Bog Turtle (<i>Glyptemys muhlenbergii</i>) Eggs in New Jersey and Pennsylvania

Zappalorti, Robert T.; Tutterow, Annalee M.; Pittman, Shannon E.; Lovich, Jeffrey E.

doi:10.2744/ccb-1237.1

Cited by 8 publications

(9 citation statements)

References 23 publications

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“…Similar to other researchers, we documented nest predation events by small mammals (Whitlock 2002, Macey 2015, Zappalorti et al 2017, Byer et al 2018). Small predator species may include short‐tailed shrew ( Blarina brevicauda ), star‐nosed mole ( Condylura cristata ), various mice species, and American mink ( Neovison vison ).…”

Section: Discussionsupporting

confidence: 90%

“…Average egg survival (0.28) was comparable to northern populations of bog turtles (range = 15-33%; Whitlock 2002, Macey 2015, Zappalorti et al 2017, Byer et al 2018; Table 3). As in our study, predation was the primary cause of egg failure across all previous studies and ranged from 51-73% (Table 3) by study, site, and year.…”

Section: Discussionmentioning

confidence: 77%

“…Status assessments, including assessments of survival at early life stages, are needed for bog turtles and other globally imperiled turtle species (van Dijk et al 2014). A limited but growing body of research has been conducted on bog turtle egg survival across its range (Whitlock 2002, Macey 2015, Zappalorti et al 2017, Byer et al 2018). Within this North Carolina study, bog turtle hatch success varied widely among the 4 sites that we intensively monitored; however, egg survival was relatively consistent within sites between 2016 and 2017.…”

Section: Discussionmentioning

confidence: 99%

“…As in our study, predation was the primary cause of egg failure across all previous studies and ranged from 51-73% (Table 3) by study, site, and year. Whitlock (2002) observed egg predation rates from 0.05-100%, and Zappalorti et al (2017) recorded hatch success as high as 83% in a given season. Whitlock (2002) and Byer et al (2018) both documented substantial nest predation events, but the predators were not identified.…”

Section: Discussionmentioning

confidence: 99%

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Hatch Success and Recruitment Patterns of the Bog Turtle

2020

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Researchers suggest that several bog turtle (Glyptemys muhlenbergii) populations in North Carolina, USA, are in decline and have few remaining individuals and low annual survival probability. Most populations are dominated by older adults with few juveniles encountered; however, the proportion of juveniles encountered in 2 populations is higher. It is unknown why the juvenile:adult ratio varies among populations. We conducted a nest monitoring study in 2016 and 2017 to test the hypothesis that sites with fewer juvenile encounters would be where nest predation was highest. We documented the fate of 272 eggs from 83 nests encountered across 7 sites in North Carolina. On average 28% of eggs hatched across all sites over both years, but we observed large variation in hatch success among sites. Predation by mesopredators and small mammals was the primary cause of nest failure. The probability of nest predation decreased with greater emergent vegetation density and increased with greater distance to the edge of the wetland. Cooler temperatures, which prolonged incubation and thus increased predation risk, may also hinder recruitment at higher elevation sites. Our observations are consistent with the hypothesis that nest predation would be highest at sites with fewer juvenile encounters. Managers concerned about low bog turtle recruitment rates should consider the role of nest predation and the potential benefits of management that increases hatch rates. © 2020 The Wildlife Society.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Hatch Success and Recruitment Patterns of the Bog Turtle

2020

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“…Each recruitment augmentation scenario assumed 0.70 of available nests are recovered for management intervention in each respective wetland (except Site A, where we modeled 0.40 nest recovery due to greater abundance), which translates to a maximum of 25 nests recovered when incorporating site‐specific abundance estimates and clutch frequency (our field observations suggests that 0.7 recovery is feasible when intensively monitored). For protected eggs, we model 0.40 average egg survival, which is based on recent observations (Macey, 2015; Zappalorti et al ., 2017). If observed unprotected egg hatch success was above the 0.40 estimate (as occurred at Sites A and B), the protected egg survival estimate was conservatively set 10% above the site‐specific one.…”

Section: Methodsmentioning

confidence: 99%

Population models reveal the importance of early life‐stages for population stability of an imperiled turtle species

Knoerr

Tutterow

Graeter

et al. 2021

Animal Conservation

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Demographic models are useful for projecting population trends, identifying life stages, most important to population dynamics, and investigating the demographic effects of potential management scenarios. We incorporated site-specific population parameters into stage-based matrix models to estimate population growth and to assess potential management scenarios for five intensively sampled (>15 years) populations of federally threatened bog turtles (Glyptemys muhlenbergii) in North Carolina, USA. Only two of the five populations modeled were stable or growing under estimated vital rates. Long-term sampling of bog turtle populations in NC suggests the declining populations in this study share several demographic characteristics with other populations in the region. Elasticity analysis revealed small changes in adult survival rates have the largest effect on population growth rate. These models also highlight that increased survival of egg and juvenile stages can sometimes buffer higher adult mortality and emigration, and reduced survival at multiple life stages can induce population-level decline. Our results indicate that management scenarios targeting increased recruitment (especially a head-start scenario) provide increased population growth among all populations, and allowed two of three declining populations to reach stability under current estimated vital rates. Population growth rates will be higher when population augmentation coincides with habitat restoration efforts that increase survival and site fidelity at all life stages. These models emphasize the importance of considering site-specific dynamics when evaluating conservation interventions for an imperiled long-lived species.

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Habitat and History Influence Abundance of Bog Turtles

2019

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Conservation of rare and endangered species requires assessment of factors that influence the current habitat associations of a species and the role of past habitat degradation in limiting occupancy or abundance. The objective of our 2011–2014 study was to determine how habitat characteristics and wetland history can predict occupancy and abundance patterns of bog turtles (Glyptemys muhlenbergii) at the fringe of their range in the southeastern United States. We used a hurdle model to examine occupancy and abundance patterns while addressing problems associated with zero‐inflated data. Occupancy patterns were weakly related to percent of the wetland containing emergent vegetation, whereas abundance patterns were predicted by the percent silt in the wetland substrate, percent forest cover, amount of habitat degradation, and recovery time since past habitat degradation. The effect of historical habitat degradation on abundance rather than occupancy patterns has rarely been documented and its effect is rarely studied in vertebrate populations. Identification of predictors of occupancy and abundance patterns will aid discovery of new populations of bog turtles and improve management of occupied wetlands. © 2019 The Wildlife Society.

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Hatching Success and Predation of Bog Turtle (Glyptemys muhlenbergii) Eggs in New Jersey and Pennsylvania

Cited by 8 publications

References 23 publications

Hatch Success and Recruitment Patterns of the Bog Turtle

Hatch Success and Recruitment Patterns of the Bog Turtle

Population models reveal the importance of early life‐stages for population stability of an imperiled turtle species

Habitat and History Influence Abundance of Bog Turtles

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