Evaluation of headstarting and release techniques for population augmentation and reintroduction of the smooth green snake

Sacerdote-Velat, Allison B; Earnhardt, Joanne M.; Mulkerin, Diane; Boehm, Daniel R.; Glowacki, Gary A.

doi:10.1111/acv.12151

Cited by 24 publications

(24 citation statements)

References 29 publications

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“…Possibly, this species was unable to persist in remnant and ruderal habitats available before restoration began at Nachusa Grasslands and has not yet colonized. Like Dekay's Brownsnakes, Smooth Greensnakes are relatively small, ranging from 107 to 388 mm SVL and 1–29 g at our Green River study site, and may have limited dispersal ability (Sacerdote‐Velat et al ). As dietary specialists on arthropods, Smooth Greensnakes may be more susceptible than other snakes to direct or indirect effects of insecticide use (Phillips et al ).…”

Section: Discussionmentioning

confidence: 94%

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Responses of grassland snakes to tallgrass prairie restoration

King

Vanek

2020

Restoration Ecology

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Understanding faunal responses to habitat restoration is important in assessing restoration success. We investigated occupancy and abundance of snakes at Nachusa Grasslands, a large-scale grassland restoration in the midwestern United States. Using artificial cover objects, we sampled within a chronosequence of 12 units converted from row-crop agriculture 2-25 years before the start of our study. Recaptures of marked snakes revealed that movement distances differed among species in accordance with differences in body size, being least in Dekay's Brownsnakes, intermediate in the Plains Gartersnakes and Common Gartersnakes, and greatest in Eastern Foxsnakes. Consistent with this result, occupancy increased with restoration age in Dekay's Brownsnakes but was unrelated to restoration age in the three larger, more mobile species. Similarly, abundance increased with restoration age in Dekay's Brownsnake but was unrelated to restoration age in other species. The Smooth Greensnake, another small-bodied snake with limited mobility, and an Illinois species of greatest conservation need, was not detected at Nachusa Grasslands. Given detection probabilities observed during a parallel study at a nearby large grassland-dominated preserve, we infer that the Smooth Greensnake is truly absent from Nachusa Grasslands. Taken together, our results demonstrate that establishment of faunal components following restoration may be time-dependent with more sedentary species colonizing only slowly (e.g. Dekay's Brownsnakes) or not at all (e.g. Smooth Greensnakes). These results emphasize the need to clearly identify faunal restoration goals and the means to achieve them. Implications for Practice• As higher order predators within grassland ecosystems, snakes provide a meaningful faunal component by which to measure restoration success.• Larger, more mobile snake species are able to occupy grassland restorations soon after conversion from rowcrop agriculture but occupancy by smaller, less mobile species may occur more slowly if at all.• Some grassland snakes may require active management to promote establishment following restoration.

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Section: Discussionmentioning

confidence: 94%

“…For this species, passive establishment appears to be insufficient to achieve conservation and management goals. Translocation may be necessary to establish Smooth Greensnakes to restored habitat (Sacerdote‐Vela et al ).…”

Section: Discussionmentioning

confidence: 99%

Responses of grassland snakes to tallgrass prairie restoration

King

Vanek

2020

Restoration Ecology

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“…Releasing animals into outdoor enclosures increased survival, site fidelity and reproductive success in reintroduced burrowing owls ( Athene cunicularia; Mitchell et al ., ). In contrast, releasing animals into outdoor enclosures (‘soft‐releases’) did not increase survival in headstarted desert tortoises ( Gopherus agassizii; Nagy et al ., ) or smooth green snakes ( Opheodrys vernalis; Sacerdote‐Velat et al ., ), and did not increase site fidelity of hare wallabies ( Lagostrophus fasciatus ; Hardman & Moro, ). Future work should test the effects of acclimation in outdoor enclosures on survival and behavior in Blanding's turtles.…”

Section: Discussionmentioning

confidence: 94%

Population reinforcement accelerates subadult recruitment rates in an endangered freshwater turtle

Carstairs

Paterson

Jäger

et al. 2019

Animal Conservation

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Wildlife diversity and abundance are declining globally and population reinforcement with captive‐reared animals is a common intervention used to prevent extinctions. Released captive‐reared individuals may undergo an acclimation period before their behavior and success is comparable to wild‐reared individuals because they lack experience with predators, complex habitats and variable environmental conditions. Quantifying post‐release acclimation effects on fitness and behavior is important for maximizing the success of reintroduction programs and for predicting the number of captive‐reared animals required for release. Endangered Blanding's turtles Emydoidea blandingii exhibit low recruitment and may benefit from population reinforcement with captive‐reared, ‘headstarted’ individuals (headstarts). We used 6 years of data to compare survival, growth, habitat use and movement ecology between wild‐hatched juvenile turtles and headstarts reared from eggs rescued from injured females. We found strong evidence of an acclimation effect in headstarts, with lower movement, growth, and survival during the first one to two years post‐release. Following this acclimation period, headstarts had movement, growth and survival similar to wild‐hatched juveniles. Habitat use did not differ between headstarts and wild‐hatched juveniles. We hypothesize that the acclimation period occurred because headstarts were introduced directly into the wild (i.e. ‘hard release’) and that providing additional support before or after release may improve the success of headstarts. Headstarts had a monthly survival probability of 0.89 in the first year post‐release, and 0.98 after the first year post‐release. We estimated that headstarts at our sites have approximately three times higher probability of surviving to 10 years of age, compared to wild‐hatched individuals at other sites. Our results highlight that headstarts should be released into habitat individually rather than in clusters, and highlight the need to investigate whether post‐release mortality of captive‐reared animals could be mitigated by increased acclimation to wild conditions, for example through prerelease periods in outdoor pens.

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“…Headstarts from temperate populations kept active year-round in captivity to maximize growth will lack overwintering experience prior to release, potentially compromising post-release over-wintering survivorship (Frazer 1992;Bjorndal et al 2003). Furthermore, omitting overwintering can reduce reproductive potential in smooth green snake (Opheodrys vernalis) headstarts, where brumation appears necessary to trigger gametogenesis (Sacerdote-Velat et al 2014). This may also prove to be a concern for turtles.…”

Section: Critiques Of the Headstarting Methods For Turtlesmentioning

confidence: 99%

A question of scale: Replication and the effective evaluation of conservation interventions

Bennett

Steiner²,

Carstairs

et al. 2017

FACETS

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Conservation interventions can keep critically endangered species from going extinct and stabilize threatened populations. The species-specific, case-by-case approaches and small sample sizes inherent to applied conservation measures are not well suited to scientific evaluations of outcomes. Debates about whether a method "works" become entrenched in a vote-counting framework. Furthermore, population-level replication is rare but necessary for disentangling the effects of an intervention from other drivers of population change. Turtle headstarting is a conservation tool that has attracted strong opinions but little robust data. Logistical limitations, such as those imposed by the long lives of turtles, have slowed experimental evaluation and constrained the use of replication or experimental controls. Headstarting project goals vary among projects and stakeholders, and success is not always explicitly defined. To facilitate robust evaluations, we provide direction for data collection and reporting to guide the application of conservation interventions in logistically challenging systems. We offer recommendations for standardized data collection that allow their valuable results to contribute to the development of best practices, regardless of the magnitude of the project. An evidence-based and collaborative approach will lead to improved program design and reporting, and will facilitate constructive evaluation of interventions both within and among conservation programs.

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Evaluation of headstarting and release techniques for population augmentation and reintroduction of the smooth green snake

Cited by 24 publications

References 29 publications

Responses of grassland snakes to tallgrass prairie restoration

Responses of grassland snakes to tallgrass prairie restoration

Population reinforcement accelerates subadult recruitment rates in an endangered freshwater turtle

A question of scale: Replication and the effective evaluation of conservation interventions

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