Headstarting as a Management Tool: A Case Study of the Plains Gartersnake

King, Richard B.; Stanford, Kristin M.

doi:10.1655/0018-0831(2006)62[282:haamta]2.0.co;2

Cited by 23 publications

(23 citation statements)

References 34 publications

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“…Worldwide, snake populations have declined from habitat loss, exacerbated by climate change, invasive species and disease (Gibbons et al ., ; Reading et al ., ). In the Midwestern US, snakes suffer losses from conversion of habitats into intensive agriculture including the Eastern Massasauga rattlesnake Sistrurus catenatus (Szymanski, ; Sheperd et al ., ), copperbelly water snake Nerodia erythrogaster neglecta (Roe, Kingsbury & Herbert, ) and plains garter snake (King & Stanford, ).…”

Section: Introductionmentioning

confidence: 99%

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

Sacerdote-Velat

Earnhardt

Mulkerin

et al. 2014

Animal Conservation

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Headstarting is a conservation technique for improving survival of species with high juvenile mortality by accelerating growth rate and increasing body size of captive-born young. With reptiles, headstarts are often kept active year-round to achieve body size goals and increase survival, omitting overwintering (brumation). As brumation is part of the life cycle of reptiles, there may be tradeoffs related to temperature response post-release when reptiles are kept active. Upon release into habitats, reptiles are either soft released, where acclimation is provided with in situ enclosures, or hard released without acclimation, directly into habitat. Soft releases have resulted in greater survival and site fidelity than hard releases, but evaluations with snakes are rare. We used a comparative approach to examine effects of brumation versus year-round activity on prerelease growth and survival of smooth green snake Opheodrys vernalis headstarts. We estimated short-term post-release daily survival rates of headstarts and compared movements of hard and soft released snakes. Despite decreases in body mass during brumation, prerelease body size, growth rate and survival did not differ among brumation treatments. Brumated headstarts exhibited rapid compensatory growth, attaining the size of active headstarts within 2 months of brumation. We observed qualitative evidence of reproductive potential in brumated snakes with the production of spermatozoa and unfertilized eggs, which was absent in active headstarts. The short-term survival rate of all headstarts during post-release tracking was 0.83 (±0.01), but we lacked power to examine differences in survival among release treatments. Daily movements did not differ among release treatments. Soft releases had slightly greater recaptures, facilitating monitoring. Although brumation comparisons produced equivalent prerelease growth and survival, as a precautionary measure for post-release survival, we recommend incorporating brumation into headstarting efforts. While further study with other reptiles is warranted, we recommend a comparative framework in planning headstarting efforts with additional species.

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Section: Introductionmentioning

confidence: 99%

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

Sacerdote-Velat

Earnhardt

Mulkerin

et al. 2014

Animal Conservation

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“…Besides maternal effects on hatchling growth, behaviors of hatchlings, especially foraging behavior, play an important role in determining juvenile fitness [King and Stanford, ]. Our data suggest that hatchling foraging behavior is a vital factor in conservation of Eastern Indigo Snakes.…”

Section: Discussionmentioning

confidence: 82%

“…From this, we conclude that the growth experienced by our caged snakes represents a reasonable model for growth likely to be experienced by snakes in the field [see also King and Stanford, ]. Those snakes that were reluctant to feed pay a consequence in lower growth rates, which can lead to a lower survival in the wild and in captivity [King and Stanford, ]. However, those individuals that consumed 1,711 g or more of food in the first 21 months appeared to be satiated as evidenced by their relatively constant high growth rate regardless of additional food intake.…”

Section: Discussionmentioning

confidence: 90%

“…All of the genera used as prey in this study occur within the proposed repatriation site for which the snakes were raised and all rearing sites offered hatchling snakes mammals, birds, amphibians, and fishes. From this, we conclude that the growth experienced by our caged snakes represents a reasonable model for growth likely to be experienced by snakes in the field [see also King and Stanford, ]. Those snakes that were reluctant to feed pay a consequence in lower growth rates, which can lead to a lower survival in the wild and in captivity [King and Stanford, ].…”

Section: Discussionmentioning

confidence: 92%

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Optimal husbandry of hatchling Eastern Indigo Snakes (Drymarchon couperi) during a captive head-start program

et al. 2015

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Optimal husbandry techniques are desirable for any headstart program, but frequently are unknown for rare species. Here we describe key reproductive variables and determine optimal incubation temperature and diet diversity for Eastern Indigo Snakes (Drymarchon couperi) grown in laboratory settings. Optimal incubation temperature was estimated from two variables dependent on temperature, shell dimpling, a surrogate for death from fungal infection, and deviation of an egg from an ovoid shape, a surrogate for death from developmental anomalies. Based on these relationships and size at hatching we determined optimal incubation temperature to be 26°C. Additionally, we used incubation data to assess the effect of temperature on duration of incubation and size of hatchlings. We also examined hatchling diets necessary to achieve optimal growth over a 21-month period. These snakes exhibited a positive linear relationship between total mass eaten and growth rate, when individuals were fed less than 1711 g of prey, and displayed constant growth for individuals exceeding 1711 g of prey. Similarly, growth rate increased linearly with increasing diet diversity up to a moderately diverse diet, followed by constant growth for higher levels of diet diversity. Of the two components of diet diversity, diet evenness played a stronger role than diet richness in explaining variance in hatchling growth. These patterns document that our goal of satiating snakes was achieved for some individuals but not others and that diets in which total grams consumed over the first 21 months of life is distributed equivalently among at least three prey genera yielded the fastest growth rates for hatchling snakes.

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“…Furthermore, headstarted and wild-hatched individuals must be distinguishable in the field, e.g., through non-harmful marking such as passive integrated transponders (Gibbons and Andrews 2004), visible implant elastomer (Davy et al 2010;Antwis et al 2014;Simon and Dörner 2014;Kozłowski et al 2017), or other tools (Auger-Méthé and Whitehead 2007;Parker et al 2013;Schoen et al 2015). For example, short-term survival rates have been compared in wild and headstarted plains garter snakes (Thamnophis radix) of similar size (King and Stanford 2006), Mona Island iguanas (Cyclura cornuta stejnegeri; Pérez- Buitrago et al 2008), and European pond turtles (Emys orbicularis; Mitrus 2005). However, biological fitness is difficult to quantify in turtles, where survivorship and fecundity require decades for direct measurement.…”

Section: Impacts Within Populationsmentioning

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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Headstarting as a Management Tool: A Case Study of the Plains Gartersnake

Cited by 23 publications

References 34 publications

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

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

Optimal husbandry of hatchling Eastern Indigo Snakes (Drymarchon couperi) during a captive head-start program

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

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