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Papers & Reports Associations between environmental pollutants and larval amphibians in wetlands contaminated by energy-related brines are potentially mediated by feeding traits
Authors: Kelly L Smalling; Chauncey W Anderson; R K Honeycutt; I M Cozzarelli,; Todd Preston; Blake R Hossack
Date: 2019-02-22 | Outlet: Environmental Pollution
Energy production in the Williston Basin, located in the Prairie Pothole Region of central North America, has increased rapidly over the last several decades. Advances in disposal practices of saline wastewaters (brines) co-produced during energy production have reduced ecological risks, but spills still occur often and legacy practices of releasing brines into the environment caused persistent salinization in many areas. Aside from sodium and chloride, these brines contain elevated concentrations of heavy metals, ammonium, volatile organic compounds, hydrocarbons and radionuclides. Amphibians are especially sensitive to chloride but interactions among other environmental pollutants are possible wetlands contaminated by brines. We collected bed sediment and larval amphibians (Ambystoma mavortium, Lithobates pipiens and Pseudacris maculata) from wetlands in Montana and North Dakota representing a range of brine contamination history and severity to determine if contamination was associated with metal concentrations in sediments and if metal accumulation in tissues varied by species and feeding traits. Brine contamination was positively associated with the concentrations of sodium and strontium in sediments and negatively correlated with mercury. However, concentrations of several metals were correlated with differences in feeding traits (grazers vs. predators), which suggests frequent contact with the sediments could lead to greater ingestion of metal-laden materials. Although many of these metals may not be directly linked with energy development, the potential additive or synergistic effects of exposure along with elevated chloride from brines could have important consequences for aquatic organisms. To effectively manage amphibian populations in wetlands contaminated by saline wastewaters we need a more robust understanding of how life history traits, species-specific susceptibilities and the physical-chemical properties of metals co-occurring in wetland sediments interact with other stressors like chloride and wetland drying.
Papers & Reports Heterogeneous responses of temperate-zone amphibian populations to climate change complicates conservation planning
Authors: Erin Muths; Thierry C Chambert; Benedikt R Schmidt; David AW Miller; Blake R Hossack; Pierre Joly; O Grolet; David E Green; David S Pilliod; Marc Cheylan; Robert N Fisher; Rebecca M McCaffery; Michael J Adams; Wendy J Palen; Jan W Arntzen; Justin Garwood; Gary M Fellers; Jean-Marc Thirion; Aurélien Besnard; Evan HC Grant
Date: 2017-12 | Outlet: Scientific Reports. DOI:10.1038/s41598-017-17105-7
The pervasive and unabated nature of global amphibian declines suggests common demographic responses to a given driver, and quantification of major drivers and responses could inform broad-scale conservation actions. We explored the influence of climate on demographic parameters (i.e., changes in the probabilities of survival and recruitment) using 31 datasets from temperate zone amphibian populations (North America and Europe) with more than a decade of observations each. There was evidence for an influence of climate on population demographic rates, but the direction and magnitude of responses to climate drivers was highly variable among taxa and among populations within taxa. These results reveal that climate drivers interact with variation in life-history traits and population-specific attributes resulting in a diversity of responses. This heterogeneity complicates the identification of conservation ?rules of thumb? for these taxa, and supports the notion of local focus as the most effective approach to overcome global-scale conservation challenges.
Papers & Reports Post-breeding movement and habitat use by Wood Frogs along an Arctic-Subarctic ecotone
Authors: Stephanie C Bishir; Blake R Hossack; L Fishback; J M Davenport
Date: 2018 | Outlet: Arctic, Antarctic, and Alpine Research 50:e1487657
By altering essential micro- and macrohabitat conditions for many organisms, climate change is already causing disproportionately great impacts on Arctic and Subarctic ecosystems. Yet, there is a lack of basic information for many species in northern latitudes, including amphibians. We used radio telemetry to study the post-breeding movements and habitat use of wood frogs (Rana sylvatica) in the Hudson Bay Lowlands near Churchill, Manitoba, Canada. We tracked 57 frogs (35 males, 22 females; mean duration = 16.8 days) from three wetlands during summer 2015 and 2016. The three wetlands were representative of the Arctic-Subarctic ecotone, with each wetland surrounded by different proportions of boreal forest and tundra. Our results indicate that the landscape scale, movement distances increased with temperature and all frogs spent more time in the tundra habitat than in boreal forest, relative to the availability of each habitat type. At the microhabitat scale (1 m2 plots), frogs selected areas with greater amounts of standing water, sedge, and shrubs. These results provide information on terrestrial movement patterns and critical habitat data for northern populations of wood frogs in a Subarctic environment, which will aid in understanding how climate change will affect amphibians in this rapidly-changing ecosystem.
Papers & Reports Increasing connectivity between metapopulation ecology and landscape ecology
Authors: P E Howell; Erin Muths; Blake R Hossack; Brent H Sigafus; Richard Chandler
Date: 2018-02 | Outlet: Ecology 99(5), 2018, pp. 1119–1128
Abstract. Metapopulation ecology and landscape ecology aim to understand how spatial structure
influences ecological processes, yet these disciplines address the problem using fundamentally different modeling approaches. Metapopulation models describe how the spatial distribution of patches affects colonization and extinction, but often do not account for the heterogeneity in the landscape between patches. Models in landscape ecology use detailed descriptions of landscape structure, but often without considering colonization and extinction dynamics. We present a novel spatially explicit modeling framework for narrowing the divide between these disciplines to advance understanding of the effects of landscape structure on metapopulation dynamics. Unlike previous efforts, this framework allows for statistical inference on landscape resistance to colonization using empirical data. We demonstrate the approach using 11 yr of data on a threatened amphibian in a desert ecosystem. Occupancy data for Lithobates chiricahuensis (Chiricahua leopard frog) were collected on the Buenos Aires National Wildlife Refuge (BANWR), Arizona, USA from 2007 to 2017 following a reintroduction in 2003. Results indicated that colonization dynamics were influenced by both patch characteristics and landscape structure. Landscape resistance increased with increasing elevation and distance to the nearest streambed. Colonization rate was also influenced by patch quality, with semi-permanent and permanent ponds contributing substantially more to the colonization of neighboring ponds relative to intermittent ponds. Ponds that only hold water intermittently also had the highest extinction rate. Our modeling framework can be widely applied to understand metapopulation dynamics in complex landscapes, particularly in systems in which the environment between habitat patches influences the colonization process.
influences ecological processes, yet these disciplines address the problem using fundamentally different modeling approaches. Metapopulation models describe how the spatial distribution of patches affects colonization and extinction, but often do not account for the heterogeneity in the landscape between patches. Models in landscape ecology use detailed descriptions of landscape structure, but often without considering colonization and extinction dynamics. We present a novel spatially explicit modeling framework for narrowing the divide between these disciplines to advance understanding of the effects of landscape structure on metapopulation dynamics. Unlike previous efforts, this framework allows for statistical inference on landscape resistance to colonization using empirical data. We demonstrate the approach using 11 yr of data on a threatened amphibian in a desert ecosystem. Occupancy data for Lithobates chiricahuensis (Chiricahua leopard frog) were collected on the Buenos Aires National Wildlife Refuge (BANWR), Arizona, USA from 2007 to 2017 following a reintroduction in 2003. Results indicated that colonization dynamics were influenced by both patch characteristics and landscape structure. Landscape resistance increased with increasing elevation and distance to the nearest streambed. Colonization rate was also influenced by patch quality, with semi-permanent and permanent ponds contributing substantially more to the colonization of neighboring ponds relative to intermittent ponds. Ponds that only hold water intermittently also had the highest extinction rate. Our modeling framework can be widely applied to understand metapopulation dynamics in complex landscapes, particularly in systems in which the environment between habitat patches influences the colonization process.
Papers & Reports Status of the Threatened Chiricahua Leopard Frog and Conservation Challenges in Sonora, Mexico, with Notes on Other Ranid Frogs and Non-native Predators
Authors: James C Rorabaugh; Blake R Hossack; Erin Muths; Brent H Sigafus; J A Lemos-Espinal
Date: 2018-04-30 | Outlet: Herpetological Conservation and Biology 13(1):17–32
In North America, ranid frogs (Ranidae) have experienced larger declines than any other amphibian family, particularly species native to the southwestern USA and adjacent Mexico; however, our knowledge of their conservation status and threats is limited in Mexico. We assessed the status of the federally-threatened (USA) Chiricahua Leopard Frog (Lithobates chiricahuensis) in Sonora, Mexico, based on a search of museum specimens, published records, unpublished accounts, and surveys of 84 sites within the geographical and elevational range of the species from 2000-2016. We also provide information on occurrence of three other native ranid frog species encountered opportunistically during our surveys. The Chiricahua Leopard Frog is known in Sonora from only 20 historical (pre-2000) localities. Searches of three historical sites from 2000-2016 did not reveal any Chiricahua Leopard Frogs; however, we found it at three previously undocumented sites in 2016, all near Cananea. To our knowledge, these records are the first observations of Chiricahua Leopard Frogs in Sonora since 1998. Differences in conservation status between the USA and Sonora are likely due to differing magnitude and distribution of threats and a comparatively aggressive recovery program in the USA. For example, key non-native predators important in the decline of the Chiricahua Leopard Frog are much less widespread in Sonora compared to the USA Southwest, but there are fewer protections and recovery actions for the frog in Sonora than in the USA. Additional surveys for the Chiricahua Leopard Frog and other amphibians in Sonora should be a priority to fully assess threats and conservation status.
News & Stories Interpretive sign highlighting the federally threatened Chiricahua Leopard Frog debuts at Buenos Aires National Wildlife Refuge
Authors: Erin Muths; Brent H Sigafus; Blake R Hossack; P E Howell
August 21, 2017
An interpretive sign was installed on August 1st, 2017 near the headquarters and visitor information office at Buenos Aires National Wildlife Refuge (BANWR, Sasabe, Arizona). The sign provides information on the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) and is located next to an example of typical habitat (a cienaga). In addition to the biology and behavior of this desert frog, the sign gives a friendly reminder to brake for amphibians on Refuge roads, especially during the summer monsoon season when amphibians are more likely to be moving between habitats; in the desert, as for many animals, the cienagas and cattle tanks retain water and are key refuges during drought.
This interpretive sign, the first highlighting an amphibian on BANWR, was originally designed to educate visitors about the Chiricahua Leopard Frog, but the sign has become a template and an inspiration for further educational efforts. Additional signs are in the works at BANWR to provide interpretive information along a planned nature walk near Refuge headquarters and at the flight pen for the federally endangered Masked Bobwhite Quail. Based on the design of the Chiricahua Leopard Frog sign, interpretive information is being created to highlight all of the diverse flora and fauna at BANWR and give the visitor a better idea of the complex and interconnected lives of the organisms they might encounter as they enjoy the scenery and arid landscape of the Refuge.
The Chiricahua Leopard Frog interpretive sign was a concept initiated during a stakeholder meeting in February 2017, at BANWR, where decision science methods were applied to discuss refuge priorities (e.g., Chiricahua Leopard Frog conservation, general refuge management). Stakeholders included personnel from U.S. Fish and Wildlife Service, Arizona Game and Fish Department, U.S. Geological Survey, and the University of Georgia. The sign was designed through collaborative effort among those entities and funded via Jones-Lovich grant in Southwestern Herpetology from the Herpetologists' League. Work on declining amphibians at BANWR and the Borderlands was initiated by Cecil Schwalbe (USGS, ARMI-retired) and has been continued by Brent Sigafus, Blake Hossack and Erin Muths (Rocky Mountain and Southwest ARMI).
Papers & Reports Widespread Legacy Brine Contamination from Oil Production Reduces Survival of Chorus Frog Larvae
Authors: Blake R Hossack; H J Puglis; William A Battaglin; Chauncey W Anderson; R K Honeycutt; Kelly L Smalling
Outlet: Environmental Pollution
Advances in drilling techniques have facilitated a rapid increase in hydrocarbon extraction from energy shales, including the Williston Basin in central North America. This area overlaps with the Prairie Pothole Region, a region densely populated with wetlands that provide numerous ecosystem services. Historical (legacy) disposal practices often released saline co-produced waters (brines) with high chloride concentrations, affecting wetland water quality directly or persisting in sediments. Despite the potential threat of brine contamination to aquatic habitats, there has been little research into its ecological effects. We capitalized on a gradient of legacy brine-contaminated wetlands in northeast Montana to conduct laboratory experiments to assess variation in survival of larval Boreal Chorus Frogs (Pseudacris maculata) reared on sediments from 3 local wetlands and a control source. To help provide environmental context for the experiment, we also measured chloride concentrations in 6 brine-contaminated wetlands in our study area, including the 2 contaminated sites used for sediment exposures. Survival of frog larvae during 46- and 55-day experiments differed by up to 88% among sediment sources (Site Model) and was negatively correlated with potential chloride exposure (Chloride Model). Five of the 6 contaminated wetlands exceeded the U.S. EPA acute benchmark for chloride in freshwater (860 mg/L) and all exceeded the chronic benchmark (230 mg/L). However, the Wetland Site model explained more variation in survival than the Chloride Model, suggesting that chloride concentration alone does not fully reflect the threat of contamination to aquatic species. Because the profiles of brine-contaminated sediments are complex, further surveys and experiments are needed across a broad range of conditions, especially where restoration or remediation actions have reduced brine-contamination. Information provided by this study can help quantify potential ecological threats and help land managers prioritize conservation strategies as part of responsible and sustainable energy development.
Papers & Reports Evaluation of wetland mitigation in the Geater Yellowstone Ecosystem: Wildlife population and community responses
Authors: L Swartz; Erin Muths; Blake R Hossack
Date: 2017-12 | Outlet: Wyoming Department of Transportation
The reconstruction of US Highway 26/287 over Togwotee Pass, Wyoming, impacted or caused the loss of natural wetlands. To comply with U.S. Army Corps of Engineers permit conditions, the Wyoming Department of Transportation (WYDOT) recently completed construction or restoration of 38 mitigation wetlands along the Highway 26-287 corridor and at the aggregate pit site at the U.S. Forest Service Blackrock Ranger Station. This study provides WYDOT information on differences among wetlands created to mitigate for wetland loss (n=10), wetlands impacted but not destroyed (n=7), and natural wetlands (n=16) relative to various aspects of wildlife that use these habitats. We compare characteristics of amphibians, a pathogenic fungus, invertebrates, and birds. Created wetlands in this study area were significantly shallower than natural and impacted wetlands and had shorter hydroperiods; but impacted wetlands were similar in physical habitat characteristics to natural wetlands. Boreal toads (Anaxyrus boreas) rapidly colonized newly constructed wetlands and annual survival and recruitment rates were similar in created and natural wetlands. Boreal chorus frogs (Pseudacris maculata) were less than half as likely to occupy created wetlands as natural and impacted wetlands but population sizes were high in at least one created wetland. Barred tiger salamanders (Ambystoma mavortium) occurred in natural and impacted wetlands at similar levels, but we observed reproduction by Columbia spotted frogs (Rana luteiventris) at only one created wetland-they were common in natural and impacted wetlands. There was no difference in the prevalence of the pathogenic fungus between created and natural wetlands. Species richness of invertebrates was lower in constructed wetlands than in natural and impacted wetlands and the community composition of invertebrates differed among wetland types. Communities in created wetlands were more likely to be dominated by flying species compared to communities in natural wetlands that had more passive dispersers such as snails and clams. We recorded bird calls in two created and two natural wetlands; species richness was similar but some riparian specialists (e.g., willow flycatcher, Wilson's warbler) were not detected at either created wetland. Our results suggest that wetland creation can be an important tool for conserving wetland-dependent wildlife. Understanding how animals use created wetlands sites is a critical component to understanding the efficacy of mitigation efforts and determining alternative (e.g., earlier) endpoints. This report highlights characteristics in created sites that are advantageous to species that are perhaps non-focal, but important members of the natural community. The data presented here provide support for earlier endpoints for determining success in created wetlands and a baseline for continued monitoring of these or other created sites.
Papers & Reports Declines revisited: long-term recovery and spatial population dynamics of tailed frog larvae after wildfire
Authors: Blake R Hossack; R K Honeycutt
Date: 2017 | Outlet: Biological Conservation
Drought has fueled an increased frequency and severity of large wildfires in many ecosystems. Despite an increase in research on wildfire effects on vertebrates, the vast majority of it has focused on short-term (<5 yrs) effects and there is still little information on the time scale of population recovery for species that decline in abundance after fire. In 2003, a large wildfire in Montana (USA) burned the watersheds of four of eight streams that we sampled for larval Rocky Mountain tailed frogs (Ascaphus montanus) in 2001. Surveys during 2004?2005 revealed reduced abundance of larvae in burned streams relative to unburned streams, with greater declines associated with increased fire extent. Rocky Mountain tailed frogs have low vagility and have several unusual life-history traits that could slow population recovery, including an extended larval period (4 yrs), delayed sexual maturity (6?8 yrs), and low fecundity (<50 eggs/yr). To determine if abundance remained depressed since the 2003 wildfire, we repeated surveys during 2014?2015 and found relative abundance of larvae in burned and unburned streams had nearly converged to pre-fire conditions within two generations. The negative effects of burn extent on larval abundance weakened >58% within 12 yrs after the fire. We also found moderate synchrony among populations in unburned streams and negative spatial autocorrelation among populations in burned streams. We suspect negative spatial autocorrelation among spatially-clustered burned streams reflected increased post-fire patchiness in resources and different rates of local recovery. Our results add to a growing body of work that suggests populations in intact ecosystems tend to be resilient to habitat changes caused by wildfire. Our results also provide important insights into recovery times of populations that have been negatively affected by severe wildfire.
Papers & Reports Informing recovery in a human-transformed landscape: drought-mediated coexistence alters population trends of an imperiled salamander and invasive predators
Authors: Blake R Hossack; R K Honeycutt; Brent H Sigafus; Erin Muths; C L Crawford; T R Jones,; J A Sorensen; James C Rorabaugh; Thierry C Chambert
Date: 2017-03-16 | Outlet: Biological Conservation 209 (2017) 377–394
Understanding the additive or interactive threats of habitat transformation and invasive species is critical for conservation, especially where climate change is expected to increase the severity or frequency of drought. In the arid southwestern USA, this combination of stressors has caused widespread declines of native aquatic and semi-aquatic species. Achieving resilience to drought and other effects of climate change may depend upon continued management, so understanding the combined effects of stressors is important. We used Bayesian hierarchical models fitted with 10-yrs of pond-based monitoring surveys for the federally-endangered Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) and invasive predators (fishes and American Bullfrogs, Lithobates catesbeianus) that threaten native species. We estimated trends in occupancy of salamanders and invasive predators while accounting for hydrological dynamics of ponds, then used a two-species interaction model to directly estimate how invasive predators affected salamander occupancy. We also tested a conceptual model that predicted that drought, by limiting the distribution of invasive predators, could ultimately benefit native species. Even though occupancy of invasive predators was stationary and their presence in a pond reduced the probability of salamander presence by 23%, occupancy of Sonoran Tiger Salamanders increased, annually, by 2.2%. Occupancy of salamanders and invasive predators both declined dramatically following the 5th consecutive year of drought. Salamander occupancy recovered quickly after return to non-drought conditions, while occupancy of invasive predators remained suppressed. Models that incorporated three time-lagged periods (1 to 4 yrs) of local moisture conditions confirmed that salamanders and invasive predators responded differently to drought, reflecting how life-history strategies shape responses to disturbances. The positive 10-yr trend in salamander occupancy and their rapid recovery after drought provided partial support for the hypothesis of drought-mediated coexistence with invasive predators. These results also suggest management opportunities for conservation of the Sonoran Tiger Salamander and other imperiled organisms in human-transformed landscapes.
Papers & Reports Additive impacts of experimental climate change increase risk to an ectotherm at the Arctic’s edge
Authors: J M Davenport; Blake R Hossack; L Fishback
Date: 2017 | Outlet: Global Change Biology
Globally, Arctic and Subarctic regions have experienced the greatest temperature increases during the last 30 years. These extreme changes have amplified threats to the freshwater ecosystems that dominate the landscape in many areas by altering water budgets. Several studies in temperate environments have examined the adaptive capacity of organisms to enhance our understanding of the potential repercussions of warming and associated accelerated drying for freshwater ecosystems. However, few experiments have examined these impacts in Arctic or Subarctic freshwater ecosystems, where the climate is changing most rapidly. To evaluate the capacity of a widespread ectotherm to anticipated environmental changes, we conducted a mesocosm experiment with wood frogs (Rana sylvatica) in the Canadian Subarctic. Three warming treatments were fully crossed with three drying treatments to simulate a range of predicted changes in wetland environments. We predicted wetland warming and drying would act synergistically, with water temperature partially compensating for some of the negative effects of accelerated drying. Across all drying regimes, a 1°C increase in water temperature increased the odds of survival by https://1.79, and tadpoles in 52-day and 64-day hydroperiod mesocosms were 4.1–4.3 times more likely to survive to metamorphosis than tadpoles in 45-day mesocosms. For individuals who survived to metamorphosis, there was only a weak negative effect of temperature on size. As expected, increased temperatures accelerated tadpole growth through day 30 of the experiment. Our results reveal that one of the dominant herbivores in Subarctic wetlands, wood frog tadpoles, are capable of increasing their developmental rates in response to increased temperature and accelerated drying, but only in an additive manner. The strong negative effects of drying on survival, combined with lack of compensation between these two environmental drivers, suggest changes in the aquatic environment that are expected in this ecosystem will reduce mean fitness of populations across the landscape.
Papers & Reports Even with forewarning, challenges remain in developing a proactive response to emerging infectious diseases
Authors: Evan HC Grant; Erin Muths; R A Katz; Stefano Canessa; Michael J Adams; Jennifer R Ballard; Lee Berger; Cheryl J Briggs; J H Coleman; M J Gray; Maria-Richetta C Hopkins; Reid N Harris; Blake R Hossack; Kathryn P Huyvaert; Jonathan E Kolby; Karen R Lips; Robert E Lovich; Hamish I McCallum; Joseph R Mendelson III; Priya Nanjappa; Deanna H Olson; Jenny G Powers; Katherine LD Richgels; Robin E Russell; Benedikt R Schmidt
Outlet: Frontiers in Ecology and Evolution
Despite calls for improving responses to emerging infectious diseases of wildlife, management is seldom considered until a disease has been detected in affected populations. Reactive approaches may limit the potential for control and increase total response costs. An alternative, proactive, management framework can identify immediate actions that reduce future impacts even before a disease is detected, as well as prepare actions conditional on disease emergence. We identify four main challenges to developing proactive management strategies for the newly discovered salamander pathogen, Batrachochytrium salamandrivorans (Bsal). Given that deep uncertainty is a hallmark of wildlife disease management and decisions are often complicated by multiple competing objectives, we advocate using decision analysis to create and evaluate trade-offs among proactive (pre-emergence) and reactive (post-emergence) management. Using principles from decision analysis, natural resources agencies and policy-makers can utilize a variety of tools to improve the development of management strategies for emerging infectious diseases.
Papers & Reports Amphibian dynamics in constructed ponds on a wildlife refuge: developing expected responses to hydrological restoration
Authors: Blake R Hossack
Date: 2016 | Outlet: Hydrobiologia
Management actions are based upon predictable responses. To form expected responses to restoration actions, I estimated habitat relationships and trends (2002&#8210;2015) for four pond-breeding amphibians on a wildlife refuge (Montana, USA) where changes to restore historical hydrology to the system greatly expanded (&#8805;8 times) the flooded area of the primary breeding site for western toads (Anaxyrus boreas). Additional restoration actions are planned for the near future, including removing ponds that provide amphibian habitat. Multi-season occupancy models based on data from 15 ponds sampled during 7 years revealed that the number of breeding subpopulations increased modestly for Columbia spotted frogs (Rana luteiventris) and was stationary for long-toed salamanders (Ambystoma macrodactylum) and Pacific treefrogs (Pseudacris regilla). For these three species, pond depth was the characteristic that was associated most frequently with occupancy or changes in colonization and extinction. In contrast, a large decrease in colonization by western toads explained the decline from eight occupied ponds in 2002 to two ponds in 2015. This decline occurred despite an increase in wetland area and the colonization of a newly-created pond. These changes highlight the challenges of managing for multiple species and how management responses can be unpredictable, possibly reducing the efficacy of targeted actions.
Papers & Reports Influence of climate drivers on colonization and extinction
Authors: Andrew M Ray; W R Gould; Blake R Hossack; A Sepulveda; D Thoma; Debra A Patla; R Daley; Robert Al-Chokhachy
Date: 2016 | Outlet: Ecosphere 7:1-21
Freshwater wetlands are particularly vulnerable to climate change. Specifically, changes in
temperature, precipitation, and evapotranspiration (i.e., climate drivers) are likely to alter flooding regimes of wetlands and affect the vital rates, abundance, and distributions of wetland-dependent species. Amphibians may be among the most climate-sensitive wetland-dependent groups as many species rely on shallow or intermittently flooded wetland habitats for breeding. Here, we integrated multiple years of high-resolution gridded climate and amphibian monitoring data from Grand Teton and Yellowstone National Parks to explicitly model how variations in climate drivers and habitat conditions affect the occurrence and breeding dynamics (i.e., annual extinction and colonization rates) of amphibians. Our results showed that models incorporating climate drivers outperformed models of amphibian breeding dynamics that were exclusively habitat based. Moreover, climate-driven variation in extinction rates, but not colonization rates, disproportionately influenced amphibian occupancy in monitored wetlands. Long-term monitoring from national parks coupled with high-resolution climate data sets will be crucial to describing population dynamics and characterizing the sensitivity of amphibians and other wetland-dependent species to climate change. Further, long-term monitoring of wetlands in national parks will help reduce uncertainty
surrounding wetland resources and strengthen opportunities to make informed, science-based
decisions that have far-reaching benefits.
temperature, precipitation, and evapotranspiration (i.e., climate drivers) are likely to alter flooding regimes of wetlands and affect the vital rates, abundance, and distributions of wetland-dependent species. Amphibians may be among the most climate-sensitive wetland-dependent groups as many species rely on shallow or intermittently flooded wetland habitats for breeding. Here, we integrated multiple years of high-resolution gridded climate and amphibian monitoring data from Grand Teton and Yellowstone National Parks to explicitly model how variations in climate drivers and habitat conditions affect the occurrence and breeding dynamics (i.e., annual extinction and colonization rates) of amphibians. Our results showed that models incorporating climate drivers outperformed models of amphibian breeding dynamics that were exclusively habitat based. Moreover, climate-driven variation in extinction rates, but not colonization rates, disproportionately influenced amphibian occupancy in monitored wetlands. Long-term monitoring from national parks coupled with high-resolution climate data sets will be crucial to describing population dynamics and characterizing the sensitivity of amphibians and other wetland-dependent species to climate change. Further, long-term monitoring of wetlands in national parks will help reduce uncertainty
surrounding wetland resources and strengthen opportunities to make informed, science-based
decisions that have far-reaching benefits.
News & Stories ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May 2016
Authors: Erin Muths; Blake R Hossack; Brent H Sigafus
June 23, 2016
ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May. Reports existed of the presence of this salamander in Sonora, but the spatial extent of its range is unknown. The Sonoran Tiger Salamander is federally endangered in the US and is found only in the San Rafael Valley in southern Arizona. The identification of additional populations in nearby Sonora has implications for multiple conservation concerns including population biology, genetics, and disease. Data collected about its presence and abundance across the border will contribute to the identification of management objectives and subsequent implementation of conservation actions. The surveys were a collaborative effort with logistical support from Naturalia (http://www.naturalia.org.mx/) that included the expertise of Naturalia employees Daniel Toyos and Ramon Babuca. The trip also benefitted from assistance from Guillermo Molina (Instituto Tecnológico Superior De Cananea), Julio Lemos Espinal (UNAM), and students David Hurtado and Aline Estrella. Jim Rorabaugh contributed much to the trip by sharing knowledge of the Sonoran system gained from his previous expeditions focused on salamanders in Mexico. The effort was based at Rancho Los Fresnos, a Naturalia property located north of the town of Cananea and adjacent to the US–Mexico border. The group sampled a variety of sites on Rancho Los Fresnos, as well as surrounding ranches and locations to the south of Cananea. Tiger salamanders reside primarily in man-made or modified earthen stock tanks. These habitats were seined for salamanders and water samples were collected to test for environmental DNA (eDNA) from salamanders, invasive American bullfrogs, federally-threatened (USA) Chiricahua leopard frogs, and pathogens that cause amphibian diseases. Buccal swabs were collected from captured salamanders for genetic analyses (there is uncertainty in determining the difference among closely related salamanders in the field); and skin swabs were collected to test for disease (both Batrachochytrium salamandrivorans and B. dendrobatidis). This ongoing project has already produced one publication (Hossack et al. 2016. Notes on the Distribution of Tiger Salamanders (Presumed Ambystoma mavortium stebbinsi) in Sonora, Mexico. Herpetological Review 47(2): 177-180), and another is in preparation (Hossack et al. Informing recovery of an imperiled, endemic salamander: coupled dynamics and test of drought-mediated coexistence with invasive predators).
Papers & Reports Survival estimates for reintroduced populations of the Chiricahua Leopard Frog (Lithobates chiricahuensis)
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; Richard Chandler
Date: 2016 | Outlet: Copeia. 104.4: 824-830.
Global amphibian declines have been attributed to a number of factors including disease, invasive species, habitat degradation, and climate change. Reintroduction is one management action that is commonly used with the goal of recovering imperiled species. The success of reintroductions varies widely and evaluating their efficacy requires estimates of population viability metrics, such as underlying vital rates and trends in abundance. Although rarely quantified, assessing vital rates for recovering populations provides a more mechanistic understanding of population growth than numerical trends in population occupancy or abundance. We used three years of capture-mark-recapture data from three breeding ponds and a Cormack-Jolly-Seber model to estimate annual apparent survival for reintroduced populations of the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) at the Buenos Aires National Wildlife Refuge (BANWR), in the Altar Valley, Arizona, USA. To place our results in context, we also compiled published survival estimates for other ranids. Average apparent survival of Chiricahua Leopard Frogs at BANWR was https://0.27 (95% CI [https://0.07, 0.74]) and average individual capture probability was https://0.02 (95% CI [0, 0.05]). Our apparent survival estimate for Chiricahua Leopard Frogs is lower than for most other ranids, and is not consistent with recent research that showed metapopulation viability in the Altar Valley is high. We suggest that low apparent survival may be indicative of high emigration rates. We recommend that future research should estimate emigration rates so that actual, rather than apparent, survival can be quantified to improve population viability assessments of threatened species following reintroduction efforts.
Papers & Reports INFORMING RECOVERY OF THE ENDANGERED SONORAN TIGER SALAMANDER: 10-YEAR TRENDS IN OCCUPANCY OF SALAMANDERS, INVASIVE PREDATORS, AND THEIR CO-OCCURRENCE
Authors: Blake R Hossack; R K Honeycutt; Thierry C Chambert; Brent H Sigafus; T R Jones,; J A Sorensen; James C Rorabaugh; Erin Muths
Outlet: Unpublished Report (see https://doi.org/10.1016/j.biocon.2017.03.004)
The Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) occurs in a single valley that spans the USA-Mexico border and was listed as federally-endangered in 1997. The listing was driven by a variety of threats, including small geographic range and threats from invasive predators. The recovery plan for this subspecies requires scientifically-credible estimates of changes in occurrence of the Sonoran Tiger Salamander and invasive predators before further evaluation of the listing status. The recent completion of a 10-year (2004–2013) monitoring program, coordinated by the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service, generated data sufficient to estimate (1) trends in breeding site occupancy by the Sonoran Tiger Salamander, (2) trends in occupancy of introduced predators, and (3) probability of co-occurrence between Sonoran Tiger Salamanders and invasive predators. We used Bayesian hierarchical models to estimate annual probabilities of occupancy and co-occurrence, after adjusting for imperfect detection. Our analyses showed that pond-level occupancy of Sonoran Tiger Salamanders increased by an estimated 2.2% (95% credible interval [CI] = 0.4%–3.8%) per year. Occupancy of invasive predators decreased by an estimated 0.7% (95% CI = −2.4%–0.7%) per year. In ponds with water, presence of invasive predators reduced salamander occupancy by 23.01% (95% CI = 8.72–43.73) across the 10-yr monitoring program. These results will assist in evaluating the status of the Sonoran Tiger Salamander and prioritizing management actions that are supported by defensible estimates.
Papers & Reports Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Authors: Evan HC Grant; David AW Miller; Benedikt R Schmidt; Michael J Adams; Staci M Amburgey; Thierry C Chambert; Sam S Cruickshank; Robert N Fisher; David E Green; Blake R Hossack; P TJ Johnson; M B Joseph; Tracy A. Rittenhouse; Maureen E Ryan; Hardin J Waddle; Susan C Walls; Larissa L Bailey; Gary M Fellers; Thomas A Gorman; Andrew M Ray; David S Pilliod; S J Price; D Saenz; Erin Muths
Date: 2016-05-23 | Outlet: Scientific Reports xx:xxx-xxx
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a "smoking gun" was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.
Papers & Reports Re-evaluating geographic variation in life-history traits of a widespread Nearctic amphibian
Authors: J M Davenport; Blake R Hossack
Date: 2016 | Outlet: Journal of Zoology 299: 304-310
Animals from cold environments are usually larger than animals from warm environments, which often produces clines in body size. Because variation in body size can lead to trade-offs between growth and reproduction, life-history traits should also vary across climatic gradients. To determine if life-history traits of wood frogs (Rana sylvatica) vary with climate, we examined female and male body length, clutch size, and ovum size from 37 locations across an unprecedented 32° of latitude. In conflict with recent research, body size and ovum size decreased in cold climates and at higher latitudes. Clutch size did not vary with climate or latitude, but reproductive effort (clutch size:female size) did, suggesting selection for a life-history traits that favors maximizing propagule number over propagule size in cold climates. With accelerating climate change that will expose populations to novel environmental conditions, it is important to identify the limits of adaptation, which can be informed by greater understanding of variation in life-history traits.
Papers & Reports Estimating abundance in the presence of species uncertainty
Authors: Thierry C Chambert; Blake R Hossack; L Fishback; J M Davenport
Outlet: Methods in Ecology and Evolution