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At least 217 records · Page 12Linked to original sources
USGS2014

Prioritizing bird conservation actions in the Prairie Hardwood transition of the Midwestern United States

Large-scale planning for the conservation of species is often hindered by a poor understanding of factors limiting populations. In regions with declining wildlife populations, it is critical that objective metrics of conservation success are developed to ensure that conservation actions achieve desired results. Using spatially explicit estimates of bird abundance, we evaluated several management alternatives for conserving bird populations in the Prairie Hardwood Transition of the United States. We designed landscapes conserving species at 50% of their current predicted abundance as well as landscapes attempting to achieve species population targets (which often required the doubling of current abundance). Conserving species at reduced (half of current) abundance led to few conservation conflicts. However, because of extensive modification of the landscape to suit human use, strategies for achieving regional population targets for forest bird species would be difficult under even ideal circumstances, and even more so if maintenance of grassland bird populations is also desired. Our results indicated that large-scale restoration of agricultural lands to native grassland and forest habitats may be the most productive conservation action for increasing bird population sizes but the level of landscape transition required to approach target bird population sizes may be societally unacceptable.

Illinois;Indiana;Iowa;Michigan;Minnesota;Wisconsin↗
USGS2026

A regional simulation modeling framework for evaluating invasive annual grass management across the sagebrush biome

Invasive annual grasses (IAG) continue to spread within the sagebrush biome of the western United States, degrading plant communities and wildlife habitat, decreasing forage for ranching livelihoods, and heightening wildfire risk. Effective management of IAGs requires action and long-term strategic planning across the sagebrush biome, but the cumulative effects of IAG treatments over time and space are not well understood, especially over broad extents defined for strategies like the Sagebrush Conservation Design. We developed a simulation model and sampling framework that allow local-scale actions to be ‘scaled up’ to evaluate large-scale regional and biome-wide management strategy outcomes. We worked with natural resource managers and experts to co-develop a spatially explicit state-and-transition simulation model of IAG dynamics in sagebrush landscapes that can be used to evaluate alternative management strategies. We evaluated our framework by contrasting two baseline scenarios in terms of their long-term effects on the sagebrush biome. We show that focusing management efforts on moderate to high IAG cover was effective at reducing full conversion to IAGs but failed to prevent widespread establishment of IAGs in core sagebrush areas, exposing them to increased risk of wildfire and wildlife habitat degradation. The results of our model help quantify the extent of the problem that IAGs pose to sagebrush ecosystems given current knowledge and management efforts. Our framework provides a platform to explore alternative management strategy outcomes and can help managers develop informed conservation plans with realistic expectations for return on investment of resources committed to sagebrush landscapes.

Arizona, California, Colorado, Idaho, Montana, Nev↗
USGS2003

Bird communities, roads and development: Prospects and constraints of applying empirical models

Our objectives were to explain the prospects and constraints of applying empirical models that relate bird community metrics to broad-scale characteristics of roads and development. We explored the practical value of regression models that were derived for a large protected area in the Chihuahuan Desert. These models related bird species richness, relative abundance, or probability of occurrence to total length of roads within each of two spatial extents (1- and 2-km radii), distance to the nearest road, distance to the nearest development, or the two-way interactions of these variables. Empirical models can be used to inform conservation decisions, to parameterise simulation models for conservation planning, to identify threshold levels of road and development variables, and to determine the focus of management experiments for confirmatory hypothesis testing and improvement of model realism.

Biological Conservation↗
USGS2020

Moving from decision to action in conservation science

Biodiversity loss is a major threat to the integrity of ecosystems and is projected to worsen, yet the path to successful conservation remains elusive. Decision support frameworks (DSFs) are increasingly applied by resource managers to navigate the complexity, uncertainty, and differing socio-ecological objectives inherent to conservation problems. Most published conservation research that uses DSFs focuses on analytical stages (e.g., identifying an optimal decision), making it difficult to assess and learn from previous examples in a conservation practice context. Here, we (1) evaluate the relationship between the application of decision science and the resulting conservation outcomes, and (2) identify and address existing barriers to the application of DSFs to conservation practice. To do this, we develop a framework for evaluating conservation initiatives using decision science that emphasizes setting attainable goals, building momentum, and obtaining partner buy-in. We apply this framework to a systematic review of amphibian conservation decision support projects, including a follow-up survey of the pertinent conservation practitioners, stakeholders, and scientists. We found that all projects identified optimal solutions to reach stated objectives, but positive conservation outcomes were limited when implementation challenges arose. Further, we identified multiple barriers (e.g., dynamic and hierarchical leadership, scale complexity, limited resource availability) that can inhibit the progression from decision identification to action implementation (i.e., ‘decision-implementation gap’), and to successful conservation outcomes. Based on these results, we provide potential actionable steps and avenues for future development of DSFs to facilitate the transition from decision to action and the realization of conservation successes.

Biological Conservation↗
USGS2021

A watershed moment: Analysis of sub-basins refocuses the geography of turtle conservation across the globe

Conservation planners use a variety of decision-making tools, many of which require identifying and prioritizing spatial units based on their biodiversity and levels of imperilment. Turtles are highly imperiled, but present schemes for determining global priority areas are focused mostly on broad regional scales. We conduct the first global evaluation of turtle biodiversity and imperilment at a sub-basin level to identify geographically smaller areas of high conservation value, and compare with these existing prioritizations. We employed two spatial analyses—bivariate maps and local indicator of spatial association (LISA)—to identify and prioritize sub-basin clusters based on multiple biodiversity and conservation metrics in addition to species richness. Most high-priority sub-basin clusters were located along tropical and subtropical coastlines. A new area of global significance for turtle conservation was identified in southwest India. Many sub-basins of the Indomalayan Realm were clustered as high or intermediate priority, with large clusters of high-priority sub-basins also in tropical Australasia. Other high and intermediate priority sub-basin clusters were found in the Afrotropical, Neotropical, and Nearctic realms, often in previously recognized turtle biodiversity hotspots. Many conservation-priority sub-basins with high turtle-species richness and endemism are in lowland and coastal areas where endemics (some from ancient lineages) are imperiled in association with a high human footprint. Our findings reiterate the global significance of Asia as a key area of chelonian conservation need, while identifying focal areas across the globe where the need for targeted turtle conservation is especially great.

Biological Conservation↗
USGS2022

Coupling process-based and empirical models to assess management options to meet conservation goals

Conservation lands face a mounting threat of ecosystem transformation and the loss of biodiversity from the invasion of fire-prone perennial and annual grasses. Managers must make difficult decisions to find efficient ways to expend limited resources to manage large and complex landscapes amidst substantial uncertainty regarding effective treatment strategies, climates, and invader-induced novel processes. We developed a state-and-transition simulation model coupled with a fire behavior model to study impacts to native biodiversity and fire regimes in a national park invaded by a perennial grass. We evaluated resources required to meet management objectives, and how to spatially allocate available resources efficiently and effectively. Management strategies and ecological scenarios strongly influenced the ability to minimize potential impacts; the inclusion of a new management strategy, aerial precision spot spraying targeting low cover levels in remote regions, was needed to supplement current treatments that can only target large, dense patches. Adding this new treatment method may be enough to conserve the desert ecosystem from small scale transformation through invasive competition and from broad functional transformations through invasive-induced fire regime changes. Spot spraying may also be highly beneficial if wetter monsoonal conditions create faster growth rates, decreasing the ability to contain the invasion even with unlimited management resources. Given current annual budgets for control, and the new treatment option, invasion control and preservation of native biodiversity may be possible regardless of spatial prioritization. Coupled empirical and process-based models efficiently simulated the effects of management activities, quantifying potential management costs and ecological impacts, while considering a wide range of possible future uncertainties associated with climate, spread rates, and wildfires lacking historical precedent. These techniques could be applied to other situations to evaluate the feasibility of conservation goals and to determine actions that would be most efficient and effective in meeting those goals.

Arizona↗
USGS2018

Using the value of information to improve conservation decision making

Conservation decisions are challenging, not only because they often involve difficult conflicts among outcomes that people value, but because our understanding of the natural world and our effects on it is fraught with uncertainty. Value of Information (VoI) methods provide an approach for understanding and managing uncertainty from the standpoint of the decision maker. These methods are commonly used in other fields (e.g., economics, public health) and are increasingly used in biodiversity conservation. This decision analytical approach can identify the best management alternative to select where the effectiveness of interventions is uncertain, and can help to decide when to act and when to delay action until after further research. We review the use of VoI in the environmental domain, reflect on the need for greater uptake of VoI, particularly for strategic conservation planning, and suggest promising areas for new research. We also suggest common reporting standards as a means of increasing the leverage of this powerful tool. The environmental science, ecology and biodiversity categories of the Web of Knowledge were searched using the terms ‘Value of Information,’ ‘Expected Value of Perfect Information,’ and the abbreviation ‘EVPI.’ Google Scholar was searched with the same terms, and additionally the terms decision and biology, biodiversity conservation, fish, or ecology. We identified 1225 papers from these searches. Included studies were limited to those that show an application of VoI in biodiversity conservation rather than simply describing the method. All examples of use of VOI were summarised regarding the application of VoI, the management objectives, the uncertainties, models used, how the objectives were measured, and the type of VoI. While the use of VoI appears to be on the increase in biodiversity conservation, the reporting of results is highly variable, which can make it difficult to understand the decision context and which uncertainties were considered. Moreover, it was unclear if, and how, the papers informed management and policy interventions, which is why we suggest a range of reporting standards that would aid the use of VoI. The use of VoI in conservation settings is at an early stage. There are opportunities for broader applications, not only for species-focussed management problems, but also for setting local or global research priorities for biodiversity conservation, making funding decisions, or designing or improving protected area networks and management. The long-term benefits of applying VoI methods to biodiversity conservation include a more structured and decision-focused allocation of resources to research.

Biological Reviews↗
USGS2011

A decision-analytic approach to the optimal allocation of resources for endangered species consultation

The resources available to support conservation work, whether time or money, are limited. Decision makers need methods to help them identify the optimal allocation of limited resources to meet conservation goals, and decision analysis is uniquely suited to assist with the development of such methods. In recent years, a number of case studies have been described that examine optimal conservation decisions under fiscal constraints; here we develop methods to look at other types of constraints, including limited staff and regulatory deadlines. In the US, Section Seven consultation, an important component of protection under the federal Endangered Species Act, requires that federal agencies overseeing projects consult with federal biologists to avoid jeopardizing species. A benefit of consultation is negotiation of project modifications that lessen impacts on species, so staff time allocated to consultation supports conservation. However, some offices have experienced declining staff, potentially reducing the efficacy of consultation. This is true of the US Fish and Wildlife Service's Washington Fish and Wildlife Office (WFWO) and its consultation work on federally-threatened bull trout (Salvelinus confluentus). To improve effectiveness, WFWO managers needed a tool to help allocate this work to maximize conservation benefits. We used a decision-analytic approach to score projects based on the value of staff time investment, and then identified an optimal decision rule for how scored projects would be allocated across bins, where projects in different bins received different time investments. We found that, given current staff, the optimal decision rule placed 80% of informal consultations (those where expected effects are beneficial, insignificant, or discountable) in a short bin where they would be completed without negotiating changes. The remaining 20% would be placed in a long bin, warranting an investment of seven days, including time for negotiation. For formal consultations (those where expected effects are significant), 82% of projects would be placed in a long bin, with an average time investment of 15. days. The WFWO is using this decision-support tool to help allocate staff time. Because workload allocation decisions are iterative, we describe a monitoring plan designed to increase the tool's efficacy over time. This work has general application beyond Section Seven consultation, in that it provides a framework for efficient investment of staff time in conservation when such time is limited and when regulatory deadlines prevent an unconstrained approach. ?? 2010.

Biological Conservation↗
USGS2018

Stream fish colonization but not persistence varies regionally across a large North American river basin

Many species have distributions that span distinctly different physiographic regions, and effective conservation of such taxa will require a full accounting of all factors that potentially influence populations. Ecologists recognize effects of physiographic differences in topography, geology and climate on local habitat configurations, and thus the relevance of landscape heterogeneity to species distributions and abundances. However, research is lacking that examines how physiography affects the processes underlying metapopulation dynamics. We used data describing occupancy dynamics of stream fishes to evaluate evidence that physiography influences rates at which individual taxa persist in or colonize stream reaches under different flow conditions. Using periodic survey data from a stream fish assemblage in a large river basin that encompasses multiple physiographic regions, we fit multi-species dynamic occupancy models. Our modeling results suggested that stream fish colonization but not persistence was strongly governed by physiography, with estimated colonization rates considerably higher in Coastal Plain streams than in Piedmont and Blue Ridge systems. Like colonization, persistence was positively related to an index of stream flow magnitude, but the relationship between flow and persistence did not depend on physiography. Understanding the relative importance of colonization and persistence, and how one or both processes may change across the landscape, is critical information for the conservation of broadly distributed taxa, and conservation strategies explicitly accounting for spatial variation in these processes are likely to be more successful for such taxa.

Alabama, Florida, Georgia↗
USGS2026

Wildfire smoke reduces the vocal activity of imperiled grassland birds in New York State

Smoke from new fire regimes driven by climate change may affect biodiversity in new regions of the world. Wildfires that occurred in eastern Canada in 2023 burned nearly 7.8 million hectares of forest, sending smoke throughout the northeastern United States. We leveraged passive acoustic monitoring to investigate real-time effects of wildfire smoke on vocalization behavior of globally imperiled grassland birds during the breeding season in open land covers across New York State. We determined an overall negative effect of elevated smoke levels on breeding grassland bird vocal activity. We observed the strongest vocalization responses in Bobolink ( Dolichonyx oryzivorus ) – a colonial breeding, grassland-obligate species; Bobolink vocal activity sharply dropped during intense smoke early in the breeding season, yet increased during a milder smoke event later in the breeding season. Our results indicate that wildfire smoke can present an additive stressor to already imperiled grassland bird species via potential fitness reductions from decreased communication. While some aspects of smoke exposure may be uncontrollable, our results suggest that increased attention to conservation practices that promote grassland birds in the Northeast could be prioritized to offset negative effects of increased smoke associated with global change.

New York↗
USGS2007

Second chance for the plains bison

Before European settlement the plains bison ( Bison bison bison ) numbered in the tens of millions across most of the temperate region of North America. Within the span of a few decades during the mid- to late-1800s its numbers were reduced by hunting and other factors to a few hundred. The plight of the plains bison led to one of the first major movements in North America to save an endangered species. A few individuals and the American Bison Society rescued the remaining animals. Attempts to hybridize cattle and bison when bison numbers were low resulted in extensive cattle gene introgression in bison. Today, though approximately 500,000 plains bison exist in North America, few are free of cattle gene introgression, 96% are subject to anthropogenic selection for commodity production, and only 4% are in herds managed primarily for conservation purposes. Small herd size, artificial selection, cattle-gene introgression, and other factors threaten the diversity and integrity of the bison genome. In addition, the bison is for all practical purposes ecologically extinct across its former range, with multiple consequences for grassland biodiversity. Urgent measures are needed to conserve the wild bison genome and to restore the ecological role of bison in grassland ecosystems. Socioeconomic trends in the Great Plains, combined with new information about bison conservation needs and new conservation initiatives by both the public and public sectors, have set the stage for significant progress in bison conservation over the next few years.

Biological Conservation↗
USGS2016

Considering transient population dynamics in the conservation of slow life-history species: An application to the sandhill crane

The importance of transient dynamics of structured populations is increasingly recognized in ecology, yet these implications are not largely considered in conservation practices. We investigate transient and long-term population dynamics to demonstrate the process and utility of incorporating transient dynamics into conservation research and to better understand the population management of slow life-history species; these species can be theoretically highly sensitive to short- and long-term transient effects. We are specifically interested in the effects of anthropogenic removal of individuals from populations, such as caused by harvest, poaching, translocation, or incidental take. We use the sandhill crane ( Grus canadensis ) as an exemplar species; it is long-lived, has low reproduction, late maturity, and multiple populations are subject to sport harvest. We found sandhill cranes to have extremely high potential, but low likelihood for transient dynamics, even when the population is being harvested. The typically low population growth rate of slow life-history species appears to buffer against many perturbations causing large transient effects. Transient dynamics will dominate population trajectories of these species when stage structures are highly biased towards the younger and non-reproducing individuals, a situation that may be rare in established populations of long-lived animals. However, short-term transient population growth can be highly sensitive to vital rates that are relatively insensitive under equilibrium, suggesting that stage structure should be known if perturbation analysis is used to identify effective conservation strategies. For populations of slow life-history species that are not prone to large perturbations to their most productive individuals, population growth may be approximated by equilibrium dynamics.

Biological Conservation↗
USGS2024

Rainfall reduces the potential for competitive suppression of a globally endangered ungulate by livestock

Protected areas often are too small to house populations of wide-ranging species. Viability of wildlife populations therefore depends on whether interactions with humans and their land uses are negative, neutral, or positive. In central Iran, we measured interactions between globally endangered onagers (Equus hemionus onager) and livestock by analyzing remotely-sensed vegetation metrics within livestock grazing areas, tracking 9 animals with GPS telemetry, and assessing onagers' diet quality through analysis of fecal samples. Resource selection by onagers depended both on season and the presence of livestock. During the dry season, livestock reduced forage (some combination of forage biomass and forage quality) compared to pre-grazing periods, demonstrating potential for competitive suppression of onagers by livestock when resources are scarce. Additionally, and during both seasons, selection for forage by onagers was accentuated at night when livestock were absent, indicating onager avoidance of livestock. During the wet season, onagers exposed to livestock exhibited higher-quality diets than those that did not co-occur with livestock, suggesting that livestock grazing may potentially enhance forage quality for onagers. Consequently, collaboration with pastoralists to regularly rotate the locations of dry and wet season leases could alleviate negative effects of livestock grazing on onagers. Similar to other cases in multi-use landscapes, temporal shifts in the strength of competition—driven by diel cycles and seasonal rainfall—may characterize wildlife-livestock interactions in Iran and elsewhere in Asian rangelands. Our study highlights the possibility that conservation of an endangered mammal could be compatible with livestock production, at least during wet seasons.

Bahram-e-Goor Protected Area (BPA), Qatrouiyeh Nat↗
USGS2022

The potential of semi-structured citizen science data as a supplement for conservation decision-making: Validating the performance of eBird against targeted avian monitoring efforts

Methods are being developed to capitalize on citizen science data for research and monitoring, but these data are rarely used within established decision-making frameworks of wildlife agencies. Citizen science data are often collected at higher resolution and extent than targeted monitoring programs, and may provide complementary information. Here, we demonstrate that carefully filtered semi-structured citizen science observations, when paired with targeted survey data, can produce ecological predictions at higher resolution and extent than targeted surveys alone, and both datasets can represent complementary aspects of species' ecology. We present case studies demonstrating how citizen science data can enhance or supplement decision-making of government and conservation organizations. First, we show how the continuous spatial coverage of citizen science projects, when coupled with targeted surveys, can improve estimates of metrics used by the U.S. Fish and Wildlife Service in regulatory processes to estimate population size, and inform take limits of federally managed species nationwide. Second, we show that the spatial coverage of citizen science accommodates dynamic avian space use patterns during key times of the year, relative to standardized monitoring protocols carried out by the Illinois Natural History Survey. Lastly, we demonstrate that citizen science information can replicate estimates of migratory chronologies for the Illinois Natural History Survey and the U.S. Fish and Wildlife Service for some waterfowl species, and in some contexts can supplement missing data on abundance. These findings illustrate the value of integrating validated information from semi-structured citizen science into the current evidence base used to justify, inform, and evaluate conservation decision-making.

California, Illinois, Iowa, Missouri↗
USGS2010

Effects of an exotic prey species on a native specialist: Example of the snail kite

Despite acknowledging that exotic species can exhibit tremendous influence over native populations, few case studies have clearly demonstrated the effects of exotic prey species on native predators. We examined the effects of the recently introduced island apple snail ( Pomacea insularum ) on the foraging behavior and energetics of the endangered snail kite ( Rostrhamus sociabilis plumbeus ) in Florida. We conducted time-activity budgets: (i) on kites foraging for native Florida apple snails ( Pomacea paludosa ) in major wetland units within the kites’ range that had not been invaded by the exotic island apple snail and (ii) on kites foraging for exotic apple snails in Lake Tohopekaliga, the only major wetland utilized by the snail kite that had suffered a serious invasion of P. insularum . When foraging for P. insularum , snail kites dropped a greater proportion of snails, and they experienced increased handling times and decreased consumption rates; however, kites foraging for P. insularum also spent a smaller proportion of the day in flight. Estimates of net daily energy balances between kites feeding on P. insularum versus P. paludosa were comparable for adults, but juveniles experienced energetic deficiencies when feeding on the exotic snail. Due to this discrepancy, we hypothesize that wetlands invaded by P. insularum , such as Lake Tohopekaliga, may function as ecological traps for the snail kite in Florida by attracting breeding adults but simultaneously depressing juvenile survival. This study highlights the conservation implications and importance of elucidating the effects that exotic species have on native specialists, especially those that are endangered, because subtle influences on behavior may have significant population consequences.

Biological Conservation↗
USGS2018

Multi-scale effects of land cover and urbanization on the habitat suitability of an endangered toad

Habitat degradation, entwined with land cover change, is a major driver of biodiversity loss. Effects of land cover change on species can be direct (when habitat is converted to alternative land cover types) or indirect (when land outside of the species habitat is altered). Hydrologic and ecological connections between terrestrial and aquatic systems are well understood, exemplifying how spatially disparate land cover conditions may influence aquatic habitats, but are rarely examined. We sought to quantify relative effects of land cover at two different but interacting scales on habitat suitability for the endangered arroyo toad ( Anaxyrus californicus ). Based on an existing distribution model for the arroyo toad and available land cover data, we estimated effects of land cover along streams and within entire watersheds on habitat suitability using structural equation modeling. Relationships between land cover and habitat suitability differed between scales, and broader, watershed-scale conditions influenced land cover along the embedded stream networks. We found anthropogenic development and forest cover at the watershed-scale negatively impacted habitat suitability, but development along stream networks was positively associated with suitability. The positive association between development along streams and habitat suitability may be attributable to increased spatial heterogeneity along urbanized streams, or related factors including policies designed to conserve riparian habitats amidst development. These findings show arroyo toad habitat is influenced by land cover across multiple scales, and can inform conservation of the species. Furthermore, our methodology can help elucidate similar dynamics with other taxa, particularly those reliant on both terrestrial and aquatic environments.

California↗
USGS2014

Modeling effects of conservation grassland losses on amphibian habitat

Amphibians provide many ecosystem services valued by society. However, populations have declined globally with most declines linked to habitat change. Wetlands and surrounding terrestrial grasslands form habitat for amphibians in the North American Prairie Pothole Region (PPR). Wetland drainage and grassland conversion have destroyed or degraded much amphibian habitat in the PPR. However, conservation grasslands can provide alternate habitat. In the United States, the Conservation Reserve Program (CRP) is the largest program maintaining grasslands on agricultural lands. We used an ecosystem services model (InVEST) parameterized for the PPR to quantify amphibian habitat over a six-year period (2007–2012). We then quantified changes in availability of amphibian habitat under various land-cover scenarios representing incremental losses (10%, 25%, 50%, 75%, and 100%) of CRP grasslands from 2012 levels. The area of optimal amphibian habitat in the four PPR ecoregions modeled (i.e., Northern Glaciated Plains, Northwestern Glaciated Plains, Lake Agassiz Plain, Des Moines Lobe) declined by approximately 22%, from 3.8 million ha in 2007 to 2.9 million ha in 2012. These losses were driven by the conversion of CRP grasslands to croplands, primarily for corn and soybean production. Our modeling identified an additional 0.8 million ha (26%) of optimal amphibian habitat that would be lost if remaining CRP lands are returned to crop production. An economic climate favoring commodity production over conservation has resulted in substantial losses of amphibian habitat across the PPR that will likely continue into the future. Other regions of the world face similar challenges to maintaining amphibian habitats.

Prairie Pothole Region↗
USGS2017

Informing recovery in a human-transformed landscape: Drought-mediated coexistence alters population trends of an imperiled salamander and invasive predators

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-years 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 years) 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-year 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.

Arizona, Sonora↗