Roles of Patch Characteristics, Drought Frequency, and Restoration in Long‐Term Trends of a Widespread Amphibian

Hossack, Blake R.; Adams, Michael J.; Pearl, Christopher A.; Wilson, Kristine W.; Bull, Evelyn L.; Lohr, Kristin; Patla, Debra A.; Pilliod, David S.; Jones, Jason M.; Wheeler, K.; Mckay, Samuel P.; Corn, Paul Stephen

doi:10.1111/cobi.12119

Cited by 43 publications

(55 citation statements)

References 51 publications

(128 reference statements)

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“…). South Cottonwood is the larger site and more resilient to drought conditions, similar to reports in Columbia spotted frogs ( Rana lutieventris ) where populations in larger water bodies were more likely to increase and withstand drought than populations in smaller water bodies (Hossack et al ). In Colorado, boreal toad breeding sites are often in beaver pond complexes (Holland et al ) and beaver activity has a positive influence on occupancy of sites by amphibians (Hossack et al ).…”

Section: Discussionsupporting

confidence: 79%

Influence of demography and environment on persistence in toad populations

et al. 2016

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Effective conservation of rare species requires an understanding of how potential threats affect population dynamics. Unfortunately, information about population demographics prior to threats (i.e., baseline data) is lacking for many species. Perturbations, caused by climate change, disease, or other stressors can lead to population declines and heightened conservation concerns. Boreal toads (Anaxyrus boreas boreas) have undergone rangewide declines due mostly to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), with only a few sizable populations remaining in the southern Rocky Mountains, USA, that are disease‐free. Despite the apparent region‐wide occurrence of Bd, our focal populations in central Colorado were disease free over a 14‐year capture‐mark‐recapture study until the recent discovery of Bd at one of the sites. We used recapture data and the Pradel reverse‐time model to assess the influence of environmental and site‐specific conditions on survival and recruitment. We then forecast changes in the toad populations with 2 growth models; one using an average lambda value to initiate the projection, and one using the most recent value to capture potential effects of the incursion of disease into the system. Adult survival was consistently high at the 3 sites, whereas recruitment was more variable and markedly low at 1 site. We found that active season moisture, active season length, and breeding shallows were important factors in estimating recruitment. Population growth models indicated a slight increase at 1 site but decreasing trends at the 2 other sites, possibly influenced by low recruitment. Insight into declining species management can be gained from information on survival and recruitment and how site‐specific environmental factors influence these demographic parameters. Our data are particularly useful because they provide baseline data on demographics in populations before a disease outbreak and enhance our ability to detect changes in population parameters potentially caused by the disease. © 2016 The Wildlife Society.

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Section: Discussionsupporting

confidence: 79%

Influence of demography and environment on persistence in toad populations

et al. 2016

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“…The strong relationship between wetland maximum depth, runoff, and spotted frog breeding persistence is consistent with habitat characteristics that contribute to population persistence and growth across the species range (Hossack et al. ). High breeding persistence probabilities of spotted frogs (and chorus frogs) are consistent with our prediction and echo the importance of maintaining permanent wetlands, especially when one considers that historical breeding is a strong indicator of future breeding for both anuran species.…”

Section: Discussionsupporting

confidence: 64%

Multistate occupancy modeling improves understanding of amphibian breeding dynamics in the Greater Yellowstone Area

Gould

Ray

Bailey

et al. 2019

Ecological Applications

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Discerning the determinants of species occurrence across landscapes is fundamental to their conservation and management. In spatially and climatologically complex landscapes, explaining the dynamics of occurrence can lead to improved understanding of short‐ vs. long‐term trends and offer novel insight on local vs. regional change. We examined the changes in occupancy for two species of anurans with different life histories over a decade using hundreds of wetland sites in Yellowstone and Grand Teton National Parks. To account for the joint dynamics of wetland drying and amphibian breeding, we adopted a multistate occupancy model as a means to investigate mechanistic relationships of observed occurrence patterns with climatological drivers of wetland hydrologic variability. This approach allowed us to decompose occupancy dynamics into habitat changes caused by wetland drying and amphibian breeding activity, conditional on available water and previous breeding state. Over our 10‐yr time series, we observed considerable variability in climate drivers and the proportion of dry wetlands. Boreal chorus frogs (Pseudacris maculata) were more responsive to changes in wetland inundation status than Columbia spotted frogs (Rana luteiventris), as indicated by higher breeding colonization probabilities under favorable (wet) conditions. Both species had high probabilities of breeding persistence in permanently inundated wetlands with prior breeding. Despite the absence of multi‐year drought in our time series, mechanistic relationships described here offer insights on how future climate variation may result in reduced and/or shifted occurrence patterns for pond‐breeding anurans in the Greater Yellowstone Area. Further, our modeling approach may prove valuable in evaluating determinants of occurrence for other species that are dependent on wetlands or other dynamic habitats.

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“…Trends in abundance of egg mass counts (a surrogate for number of breeding females) between 1991 and 2010 at 98 breeding sites varied across the northwestern U.S., but they declined 1.2% per year in the northern Rocky Mountains (Hossack et al, 2013a). One formerly-large population (>1000 adults) in central Yellowstone NP that was included in the Hossack et al (2013a) analysis declined >80% between the 1950s and 1990s and now appears close to extirpation (Turner, 1960;Patla and Peterson, 1999;Patla, unpublished data). Across the northwest U.S., declines in abundance of egg masses were linked with frequency of moderate-to-severe droughts, especially for small, temporary wetlands.…”

Section: Discussionmentioning

confidence: 99%

“…But at local scales that are most relevant to managers, enhancing beaver populations can create habitat favorable to many wetland species (e.g., extend hydroperiods, increase water temperatures) and increase population connectivity (Hood and Bayley, 2008;Popescu and Gibbs, 2009;Scherer et al, 2012). Reintroduction of beaver has been linked with recovery of rare amphibians and other wetland species (Dalbeck et al, 2007), and is now being used as a management tool specifically for rare species (Hossack et al, 2013a;Shoo et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…Drought can negatively affect population growth of amphibians through several mechanisms, including reduced extent and duration of water in wetlands that decreases larval survival, and through negative effects on vital rates of moisture-sensitive juveniles and adults (Hossack et al, 2013a;Walls et al, 2013). Drought can also increase synchrony among local populations, subsequently increasing extinction risk (Piha et al, 2007;Ruetz et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Trends in Rocky Mountain amphibians and the role of beaver as a keystone species

Hossack

Gould

Patla³

et al. 2015

Biological Conservation

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a b s t r a c tDespite prevalent awareness of global amphibian declines, there is still little information on trends for many widespread species. To inform land managers of trends on protected landscapes and identify potential conservation strategies, we collected occurrence data for five wetland-breeding amphibian species in four national parks in the U.S. Rocky Mountains during 2002-2011. We used explicit dynamics models to estimate variation in annual occupancy, extinction, and colonization of wetlands according to summer drought and several biophysical characteristics (e.g., wetland size, elevation), including the influence of North American beaver (Castor canadensis). We found more declines in occupancy than increases, especially in Yellowstone and Grand Teton national parks (NP), where three of four species declined since 2002. However, most species in Rocky Mountain NP were too rare to include in our analysis, which likely reflects significant historical declines. Although beaver were uncommon, their creation or modification of wetlands was associated with higher colonization rates for 4 of 5 amphibian species, producing a 34% increase in occupancy in beaver-influenced wetlands compared to wetlands without beaver influence. Also, colonization rates and occupancy of boreal toads (Anaxyrus boreas) and Columbia spotted frogs (Rana luteiventris) were P2 times higher in beaver-influenced wetlands. These strong relationships suggest management for beaver that fosters amphibian recovery could counter declines in some areas. Our data reinforce reports of widespread declines of formerly and currently common species, even in areas assumed to be protected from most forms of human disturbance, and demonstrate the close ecological association between beaver and wetland-dependent species.Published by Elsevier Ltd.

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Roles of Patch Characteristics, Drought Frequency, and Restoration in Long‐Term Trends of a Widespread Amphibian

Cited by 43 publications

References 51 publications

Influence of demography and environment on persistence in toad populations

Influence of demography and environment on persistence in toad populations

Multistate occupancy modeling improves understanding of amphibian breeding dynamics in the Greater Yellowstone Area

Trends in Rocky Mountain amphibians and the role of beaver as a keystone species

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