Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders (<i>Cryptobranchus alleganiensis</i>)

Hopkins, William D.; Case, Brian C.; Groffen, Jordy; Brooks, George A.; Jachowski, Cathy Bodinof; Button, Sky T.; Halligan, John; O’Brien, Rebecca L.; Kindsvater, Holly

doi:10.1086/724819

Cited by 13 publications

(50 citation statements)

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“…Our framework illustrates how multiple co-occurring threats impacting different stages of an organism's life cycle can undermine population viability and shows how the life history of hellbenders makes them particularly susceptible to extinction debt. We demonstrated that the high rates of nest failure that have been observed in the field (Hopkins et al, 2023) are sufficient to drive hellbender populations toward a geriatric age distribution and eventually to localized extinction but that this process takes decades due to the species' longevity. As a result, population declines can go unnoticed for years because adults persist on the landscape.…”

Section: Discussionmentioning

confidence: 91%

“…Because hellbenders exhibit obligate paternal care, all clutches laid are randomly assigned to a male; if there are fewer males than clutches in a given year/scenario, clutches not assigned to a male are eliminated. We assume, based on recent work (Hopkins et al, 2023), that paternal care behavior and the probability of cannibalism of eggs do not vary among males of different sizes or ages.…”

Section: Reproduction and Nest Fatesmentioning

confidence: 99%

“…The caring male occupies the nest site over winter; based on empirical observations, male presence appears to be essential for nest success. Observations of wild populations have documented nest failure due to predation, abandonment, environmental factors such as flooding, or whole-clutch cannibalism by parental males (Hopkins et al, 2023). The proportion of failing nests varies considerably across populations (Hopkins et al, 2023); therefore, we considered a range of nest failure rates in our model scenarios.…”

Section: Larval Emergencementioning

confidence: 99%

“…The proportion of nests that fail varies with the background rate of nest failure p fail (Table 2); the number of larvae that die with the loss of a nest varies depending on the size of the female that laid a clutch at that nest site. Recent empirical evidence suggests the number of larvae emerging from nests is positively correlated with initial clutch size in small clutches but shows no relationship in large clutches (Hopkins et al, 2023). We therefore modeled the number of emerging larvae per nest as an asymptotic function of the number of eggs laid in a successful nest (Figure 1e).…”

Section: Process Equation Interpretationmentioning

confidence: 99%

“…Here we develop a demographic model to understand how multiple co-occurring threats impact the population viability of a long-lived, highly fecund vertebrate with parental care. We simulate the age-structured population dynamics of hellbenders using recent data on reproductive ecology collected from artificial nest boxes (Hopkins et al, 2023). Our parameterization explicitly models the fates of individual nests and includes multiple sources of density-dependent mortality-one during the egg and hatchling stages experienced within nests and another for free-swimming larvae following emergence from nests.…”

Section: Introductionmentioning

confidence: 99%

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Concurrent threats and extinction risk in a long‐lived, highly fecund vertebrate with parental care

Brooks,

Hopkins,

Kindsvater

2024

Ecological Applications

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Detecting declines and quantifying extinction risk of long‐lived, highly fecund vertebrates, including fishes, reptiles, and amphibians, can be challenging. In addition to the false notion that large clutches always buffer against population declines, the imperiled status of long‐lived species can often be masked by extinction debt, wherein adults persist on the landscape for several years after populations cease to be viable. Here we develop a demographic model for the eastern hellbender (Cryptobranchus alleganiensis), an imperiled aquatic salamander with paternal care. We examined the individual and interactive effects of three of the leading threats hypothesized to contribute to the species' demise: habitat loss due to siltation, high rates of nest failure, and excess adult mortality caused by fishing and harvest. We parameterized the model using data on their life history and reproductive ecology to model the fates of individual nests and address multiple sources of density‐dependent mortality under both deterministic and stochastic environmental conditions. Our model suggests that high rates of nest failure observed in the field are sufficient to drive hellbender populations toward a geriatric age distribution and eventually to localized extinction but that this process takes decades. Moreover, the combination of limited nest site availability due to siltation, nest failure, and stochastic adult mortality can interact to increase the likelihood and pace of extinction, which was particularly evident under stochastic scenarios. Density dependence in larval survival and recruitment can severely hamper a population's ability to recover from declines. Our model helps to identify tipping points beyond which extinction becomes certain and management interventions become necessary. Our approach can be generalized to understand the interactive effects of various threats to the extinction risk of other long‐lived vertebrates. As we face unprecedented rates of environmental change, holistic approaches incorporating multiple concurrent threats and their impacts on different aspects of life history will be necessary to proactively conserve long‐lived species.

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Section: Discussionmentioning

confidence: 91%

Section: Reproduction and Nest Fatesmentioning

confidence: 99%

Section: Larval Emergencementioning

confidence: 99%

Section: Process Equation Interpretationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Concurrent threats and extinction risk in a long‐lived, highly fecund vertebrate with parental care

Brooks,

Hopkins,

Kindsvater

2024

Ecological Applications

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Restoring eastern hellbender (Cryptobranchus a. alleganiensis) populations through translocation of headstarted individuals

Kaunert,

Brown,

Spear

et al. 2023

Population Ecology

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Freshwater biodiversity is declining at a fast pace despite significant efforts directed toward the management and conservation of aquatic systems. Eastern hellbenders are one of North America's most iconic stream amphibian species, a sentinel of stream health, and are experiencing rapid population declines throughout most of their range. Common conservation strategies include headstarting; however, the success of this strategy for rebuilding hellbender populations and the most optimal release scenarios have largely been unassessed. We use a cohort of 205 animals released in several Ohio watersheds to evaluate the success of headstarting and reintroduction efforts over 3 years. Using PIT‐tag surveys over 25 occasions between July 2018 and November 2021 and capture–recapture models, we found that 3‐year apparent survival post‐release was 0.162 ± 0.061, with lower survival in year 1 (0.383 ± 0.058) and greater in years 2 (0.696 ± 0.086) and 3 (0.609 ± 0.154). Using demographic simulations, we found that releasing cohorts of N = 100 individuals at fewer suitable sites several times (e.g., 3 releases, 2 or 3 years apart) would be a better strategy compared to single release events across multiple sites. Additional simulations showed that eastern hellbender headstarting programs using wild eggs can be highly beneficial in producing more animals reaching adulthood (up to 7 times, if survival in captivity is assumed to be 100%) compared to development in the wild. This study emphasizes the need to monitor the success of reintroduction programs and provides evidence that headstarting can be a viable strategy for rebuilding eastern hellbender populations.

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A portable Raspberry Pi‐based camera set‐up to record behaviours of frogs and other small animals under artificial or natural shelters in remote locations

Groffen,

Hoskin

2024

Ecology and Evolution

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We describe a Raspberry Pi‐based camera system that is portable, robust and weatherproof, with a close‐up focus (2.5 cm). We show that this camera system can be used in remote locations with high rainfall and humidity. The camera has an Infrared LED light to film in dark places and can continuously record up to 21 days (504 h). We also describe how to make concrete artificial shelters to mount the camera in. One of the great strengths of this shelter/camera set‐up is that the animals choose to take up residence and can then be filmed for extended periods with no disturbance. Furthermore, we give examples of how shelters and cameras could be used to film a range of behaviours in not only many small cryptic amphibian species but also other small vertebrates and invertebrates globally.

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Filial Cannibalism Leads to Chronic Nest Failure of Eastern Hellbender Salamanders (Cryptobranchus alleganiensis)

Cited by 13 publications

References 61 publications

Concurrent threats and extinction risk in a long‐lived, highly fecund vertebrate with parental care

Concurrent threats and extinction risk in a long‐lived, highly fecund vertebrate with parental care

Restoring eastern hellbender (Cryptobranchus a. alleganiensis) populations through translocation of headstarted individuals

A portable Raspberry Pi‐based camera set‐up to record behaviours of frogs and other small animals under artificial or natural shelters in remote locations

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