Boundaries Make a Difference: The Effects of Spatial and Temporal Parameters on Conservation Planning*

Huber, Patrick R.; Greco, Steven E.; Thorne, James H.

doi:10.1080/00330121003788309

Cited by 16 publications

(13 citation statements)

References 37 publications

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“…Quantifying functional relationships between giant gartersnake vital rates and climatic variables, habitat characteristics, and management actions, and incorporating those relationships into IPMs is also an important next step. Because of the loss of >90% of their natural wetland habitats (Huber et al ), giant gartersnakes now largely inhabit created marshes and canals associated with rice agriculture (Halstead et al , Wylie et al ), and survival of adult giant gartersnakes has been linked to the amount of aquatic habitat surrounding an individual's home range (Halstead et al ). Most remaining wetlands used by giant gartersnakes are managed by manipulating the timing and amount of water released (Duffy and Kahara ).…”

Section: Discussionmentioning

confidence: 99%

Demographic factors affecting population growth in giant gartersnakes

et al. 2019

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Demographic models provide insight into which vital rates and life stages contribute most to population growth. Integral projection models (IPMs) offer flexibility in matching model structure to a species’ demography. For many rare species, data are lacking for key vital rates, and uncertainty might dissuade researchers from attempting to build a demographic model. We present work that highlights how the implications of uncertainties and unknowns can be explored by building and analyzing alternative models. We constructed IPMs for the threatened giant gartersnake (Thamnophis gigas) based on published studies to determine where management efforts could be targeted to have the greatest effect on population persistence and what unknowns remain for future research. Given uncertainty in the survival of snakes during their first year, and in the form of the size‐survival relationship, we modeled a range of scenarios and evaluated where models agree about factors influencing population growth and where discrepancies exist. For most scenarios, the survival of large adult females had the greatest influence on population growth, but the relative importance of juvenile versus adult somatic growth for population growth was dependent on the recruitment probability and the shape of the size‐survival function. More data on temporal variation and covariance among vital rates would improve stochastic models for the giant gartersnake. This paper demonstrates the effectiveness of IPMs for studying the demography of reptiles and the value of the model‐building process for formalizing what is known and unknown about the demography of rare species. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.

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Section: Discussionmentioning

confidence: 99%

Demographic factors affecting population growth in giant gartersnakes

et al. 2019

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“…Additionally, we calculated relative NR area of each ecoregion (percent of land area in each ecoregion occupied by NRs). In gap analyses, a predefined minimum extent of each ecological component is considered necessary to analyze ecological function and viability (Villard and Jonsson 2009;Huber et al 2010). These conservation thresholds assure that no ecological components are excluded from gap analyses (Margules and Pressey 2000;Villard and Jonsson 2009;Huber et al 2010).…”

Section: Methodsmentioning

confidence: 99%

“…In gap analyses, a predefined minimum extent of each ecological component is considered necessary to analyze ecological function and viability (Villard and Jonsson 2009;Huber et al 2010). These conservation thresholds assure that no ecological components are excluded from gap analyses (Margules and Pressey 2000;Villard and Jonsson 2009;Huber et al 2010). We set the threshold for our study at 10% minimum extent coverage by NRs in each ecoregion based on previous studies (Soutullo et al 2008;Jenkins and Joppa 2009;Huber et al 2010;Wu et al 2011).…”

Section: Methodsmentioning

confidence: 99%

“…This percentage was lower than the 10% policybased conservation threshold established by the Convention on Biological Diversity (CBD) that has been used to evaluate effectiveness of NR networks in many studies (e.g., Soutullo et al 2008;Jenkins and Huber et al 2010;Wu et al 2011). The 10% conservation threshold is somewhat arbitrary and does not necessarily indicate that ecological diversity (i.e., the biodiversity of an ecoregion) is represented in NR systems.…”

Section: Statewide Nr Characteristicsmentioning

confidence: 98%

“…Various science-based thresholds recommend 30%-50% NR coverage of ecoregions (Villard and Jonsson 2009;Huber et al 2010). Other authors argue that no one threshold should be applied to every ecoregion because thresholds vary between land types and species (Villard and Jonsson 2009).…”

Section: Area and Isolation Of Nrs By Ecoregionmentioning

confidence: 99%

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Extent of Alabama's Terrestrial Nature Reserve System in Representing Ecosystem Diversity: A Coarse-Filter Gap Analysis

Billue

Hart

2014

Natural Areas Journal

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Integrating growth and capture–mark–recapture models reveals size‐dependent survival in an elusive species

et al. 2018

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Citation: Rose, J. P., G. D. Wylie, M. L. Casazza, and B. J. Halstead. 2018. Integrating growth and capturemark-recapture models reveals size-dependent survival in an elusive species. Ecosphere 9(8):Abstract. Survival is a key vital rate for projecting the viability of wild populations. Estimating survival is difficult for many rare or elusive species because recapture rates of marked individuals are low, and the ultimate fate of individuals is unknown. Low recapture rates for many species have made it difficult to accurately estimate survival, and to evaluate the importance of individual and environmental covariates for survival. Individual covariates such as size are particularly difficult to include in capture-mark-recapture models for elusive species because the state of the individual is unknown during periods when it is not captured. Here, we integrate a von Bertalanffy growth model with a multi-state robust-design Cormack-Jolly-Seber model to test for a relationship between body size and survival in the elusive, threatened giant gartersnake, Thamnophis gigas. We take a Bayesian approach to model the size of an individual during periods when it was not captured and measured, which fully propagates uncertainty in this unobserved covariate. We found strong support for a positive relationship between snake size and annual survival, with survival increasing with size up to a peak for adult snakes, after which survival either declines slightly or plateaus for the largest individuals. Few captures of very small and very large individuals led to high uncertainty in the survival rates of these sizes. Survival of giant gartersnakes was also positively related to the amount of precipitation and the cover of emergent and floating vegetation at a site. To our knowledge, our study is the first to estimate a sizesurvival relationship in a snake while fully accounting for uncertainty in the size of unobserved individuals. Our results have implications for the management of this threatened species and illustrate the utility of integrating hierarchical Bayesian models to the study of survival in elusive species.

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Boundaries Make a Difference: The Effects of Spatial and Temporal Parameters on Conservation Planning*

Cited by 16 publications

References 37 publications

Demographic factors affecting population growth in giant gartersnakes

Demographic factors affecting population growth in giant gartersnakes

Extent of Alabama's Terrestrial Nature Reserve System in Representing Ecosystem Diversity: A Coarse-Filter Gap Analysis

Integrating growth and capture–mark–recapture models reveals size‐dependent survival in an elusive species

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