An objective road risk assessment method for multiple species: ranking 166 reptiles and amphibians in California

Brehme, Cheryl S.; Hathaway, Stacie A.; Fisher, Robert N.

doi:10.1007/s10980-018-0640-1

Cited by 34 publications

(30 citation statements)

References 75 publications

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“…7). This is in contrast to previous studies which hypothesized that roads should not threaten small bodied pond turtles anywhere in the U.S. (Gibbs & Shriver, 2002), but is consistent with a recent threat assessment focused on California road mortality risk across reptiles and amphibians (Brehme, Hathaway & Fisher, 2018). Our analyses indicate that road density and proximity may lead to demographic changes of small bodied pond turtles like the WPT which could in turn drive population declines.…”

Section: Discussionsupporting

confidence: 87%

“…We did so for two reasons. First, no studies have indicated that the two species differ in the distance females travel from a body of water to nest, although this is admittedly a very understudied aspect of WPT biology (Brehme, Hathaway & Fisher, 2018). Second, the number of population samples available for each species was relatively small, and pooling both taxa allowed us greater statistical power to detect trends.…”

Section: The Effects Of Roads On Sex Ratiomentioning

confidence: 99%

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Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles

Nicholson

Manzo

Devereux

et al. 2020

PeerJ

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The western pond turtle (WPT), recently separated into two paripatrically distributed species (Emys pallida and Emys marmorata), is experiencing significant reductions in its range and population size. In addition to habitat loss, two potential causes of decline are female-biased road mortality and high juvenile mortality from non-native predatory bullfrogs (Rana catesbeiana). However, quantitative analyses of these threats have never been conducted for either species of WPT. We used a combination of historical museum samples and published and unpublished field studies shared with us through personal communications with WPT field researchers (B. Shaffer, P. Scott, R. Fisher, C. Brown, R. Dagit, L. Patterson, T. Engstrom, 2019, personal communications) to quantify the effect of roads and bullfrogs on WPT populations along the west coast of the United States. Both species of WPT shift toward increasingly male biased museum collections over the last century, a trend consistent with increasing, female-biased road mortality. Recent WPT population studies revealed that road density and proximity were significantly associated with increasingly male-biased sex ratios, further suggesting female-biased road mortality. The mean body size of museum collections of E. marmorata, but not E. pallida, has increased over the last 100 years, consistent with reduced recruitment and aging populations that could be driven by invasive predators. Contemporary WPT population sites that co-occur with bullfrogs had significantly greater average body sizes than population sites without bullfrogs, suggesting strong bullfrog predation on small WPT hatchlings and juveniles. Overall, our findings indicate that both species of WPT face demographic challenges which would have been difficult to document without the use of both historical data from natural history collections and contemporary demographic field data. Although correlational, our analyses suggest that female-biased road mortality and predation on small turtles by non-native bullfrogs are occurring, and that conservation strategies reducing both may be important for WPT recovery.

show abstract

Section: Discussionsupporting

confidence: 87%

Section: The Effects Of Roads On Sex Ratiomentioning

confidence: 99%

Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles

Nicholson

Manzo

Devereux

et al. 2020

PeerJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…7). This is in contrast to previous studies which hypothesized that roads should not threaten small bodied pond turtles anywhere in the U.S. (Gibbs & Shriver, 2002), but is consistent with a recent threat assessment focused on California road mortality risk across reptiles and amphibians (Brehme et al, 2018). Our analyses indicate that road density and proximity may lead to demographic changes of small bodied pond turtles like the WPT which could in turn drive population declines.…”

Section: Discussionsupporting

confidence: 87%

“…We did so for two reasons. First, no studies have indicated that the two species differ in the distance females travel from a body of water to nest, although this is admittedly a very understudied aspect of WPT biology (but see Brehme et al, 2018). Second, the number of population samples available for each species was relatively small, and pooling both taxa allowed us greater statistical power to detect trends.…”

Section: The Effects Of Roads On Sex Ratiomentioning

confidence: 99%

Peer Review #2 of "Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles (v0.1)"

2020

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The western pond turtle (WPT), recently separated into two paripatrically distributed species (Emys pallida and Emys marmorata), is experiencing significant reductions in its range and population size. In addition to habitat loss, two potential causes of decline are female-biased road mortality and high juvenile mortality from non-native predatory bullfrogs (Rana catesbeiana). However, quantitative analyses of these threats have never been conducted for either species of WPT. We used a combination of historical museum samples and published and unpublished field studies shared with us through personal communications with WPT field researchers (B Shaffer, P Scott, R Fisher, C Brown, R Dagit, L Patterson, T Engstrom, 2019, personal communications) to quantify the effect of roads and bullfrogs on WPT populations along the west coast of the United States. Both species of WPT shift toward increasingly male biased museum collections over the last century, a trend consistent with increasing, female-biased road mortality. Recent WPT population studies revealed that road density and proximity were significantly associated with increasingly male-biased sex ratios, further suggesting female-biased road mortality. The mean body size of museum collections of E. marmorata, but not E. pallida, has increased over the last 100 years, consistent with reduced recruitment and aging populations that could be driven by invasive predators. Contemporary WPT population sites that co-occur with bullfrogs had significantly greater average body sizes than population sites without bullfrogs, suggesting strong bullfrog predation on small WPT hatchlings and juveniles. Overall, our findings indicate that both species of WPT face demographic challenges which would have been difficult to document without the use of both historical data from natural history collections and contemporary demographic field data. Although correlational, our analyses suggest that femalebiased road mortality and predation on small turtles by non-native bullfrogs are occurring, and that conservation strategies reducing both may be important for WPT recovery.

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“…In particularly, new road construction could have detrimental effects on animal populations (Prokopenko et al 2017). Like snakes, anurans, lizards and so on, most susceptible to negative road impacts (Brehme et al 2018). Based on the independent roadkill data, more than 70% of roadkill events occurred within the top 30% priority segments (Lin et al 2019).…”

Section: Implications For Forest Road Managementmentioning

confidence: 99%

Quantifying the effects of road width on roadside vegetation and soil conditions in forests

et al. 2019

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Context The majority of ecological studies of roads have focused on their deleterious effects, and these preconceptions have hampered a full evaluation of the ecological functions of roads. As an integrated indicator, road width represents comprehensive effects, including anthropogenic and natural disturbances. Objectives We try to explore the different effects produced by various road widths by considering changes in forest vegetation and soil. Methods We selected six study forests spanning from Shandong Province in the north to Guangdong Province in the south of China, and we assessed the influences of wide and narrow roads on plant species diversity, biomass, and soil properties along transects running from the forest edges and adjacent forest interior. We used a ''shape-dependent model'' to explain the factors that determine the magnitude of road effects on forests. Results Three variables measured in this study changed significantly with increasing distance from the road to the forest interior along wide roads: tree biomass, herbaceous plant biomass, and soil pH. However, no measurable biological or environmental effects were found from narrow roads. The different shapes of glades in a forest may be one reason for the various effects caused by roads of different widths. Conclusions Forest roads of different widths may have quite different ecological effects. While wider roads with large glades tend to have substantial negative impacts, small-enough roads may cause little disturbance to the forest. This suggests that not all forest roads should be perceived as the same, and narrow roads may be compatible with forest conservation.

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An objective road risk assessment method for multiple species: ranking 166 reptiles and amphibians in California

Cited by 34 publications

References 75 publications

Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles

Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles

Peer Review #2 of "Historical museum collections and contemporary population studies implicate roads and introduced predatory bullfrogs in the decline of western pond turtles (v0.1)"

Quantifying the effects of road width on roadside vegetation and soil conditions in forests

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