Targeted Conservation Actions Research Articles

Scalar considerations in population trend estimates: Implications for recovery strategy planning for species of conservation concern

ABSTRACT Broad-scale population trends are often used to identify and list species of conservation concern and as baselines to surmise which recovery actions might arrest or reverse declines. It is therefore important that trends are quantified regionally, so that finer-scale assessments can be made about the plausible causes of declines and targeted conservation actions can be implemented. We estimated regional population trends for a grassland bird, the Bobolink (Dolichonyx oryzivorus), to compare with trends from provincial analyses used for risk assessment, to identify the regions contributing most substantially to population declines. We used 45 yr of count data from the North American Breeding Bird Survey, across 35 agricultural census divisions in southern Ontario, Canada, to develop spatially explicit hierarchical Bayesian models of regional population trends. Population trends were negative in 30 of 35 census divisions, 6 of which had 95% credibility intervals (CI) that did not include zero. In 3...

Using habitat-specific population trends to evaluate the consistency of the effect of species traits on bird population change

Many species are undergoing rapid population declines, while other species have increased. Previous work has related population change to species traits to elucidate the drivers of population change. However, this assumes that these drivers operate consistently across habitats. We use national-scale monitoring data on UK bird abundance from 1994–2012 to calculate habitat-specific population trends, allowing us to evaluate whether the effect of species traits was consistent between habitats. Although we found significant interactions with habitat for traits relating to migratory behaviour, diet, nest site and habitat specialisation, the direction of these trait effects was generally consistent between habitats. This suggests that large-scale processes operating across habitats are responsible for many changes in bird populations, although processes operating within habitats can modulate the effect of these drivers. Despite this, differences in population trends between habitats remain when variation in population trends due to species identity is accounted for, indicating that some habitat effects do occur. By identifying the scale at which drivers of population change operate, it is possible to target conservation actions more directly. Population declines were most evident in woodland and urban habitats, and we suggest that these habitats should be the focus of increased research and conservation effort if declines evident in many bird species are to be reversed.

Big cats kill more livestock when wild prey reaches a minimum threshold

Livestock predation by big cats, i.e., lion (Panthera leo), tiger (Panthera tigris), leopard (Panthera pardus), jaguar (Panthera onca), snow leopard (Panthera uncia), puma (Puma concolor), and cheetah (Acinonyx jubatus), creates conflicts with humans which challenge biodiversity conservation and rural development. Deficiency of wild prey biomass is often described as a driver of such conflicts, but the question “at which level of prey density and biomass do big cats begin to kill livestock?” still remains unanswered. We applied logistic regression to meta-data compiled from recent peer-reviewed scientific publications and show that cattle predation is high when prey biomass is <812.41±1.26kg/km2, whereas sheep and goat predation is high at <544.57±1.19kg/km2, regardless of sizes of study areas and species, body masses, and population densities of big cats. Through mapping cases with known prey biomass and case-specific comparison of actual vs. threshold-predicted livestock predation we confirm the reliability of these thresholds in predicting livestock predation by big cats. The map also demonstrates that some protected areas of India, Nepal lowlands, and South Africa contain sufficient prey that makes big cats less likely to kill livestock, but in other sampled areas prey biomass is not high enough and the probabilities of livestock predation are moderate to high. We suggest that these thresholds represent important landmarks for predicting human–felid conflicts, identifying conflict hotspots, and setting priorities for targeted conservation actions. It is essential to maintain and restore wild prey to forestall local extinctions of big cats.

The difference conservation makes to extinction risk of the world's ungulates.

Previous studies show that conservation actions have prevented extinctions, recovered populations, and reduced declining trends in global biodiversity. However, all studies to date have substantially underestimated the difference conservation action makes because they failed to account fully for what would have happened in the absence thereof. We undertook a scenario-based thought experiment to better quantify the effect conservation actions have had on the extinction risk of the world's 235 recognized ungulate species. We did so by comparing species' observed conservation status in 2008 with their estimated status under counterfactual scenarios in which conservation efforts ceased in 1996. We estimated that without conservation at least 148 species would have deteriorated by one International Union for Conservation of Nature (IUCN) Red List category, including 6 species that now would be listed as extinct or extinct in the wild. The overall decline in the conservation status of ungulates would have been nearly 8 times worse than observed. This trend would have been greater still if not for conservation on private lands. While some species have benefited from highly targeted interventions, such as reintroduction, most benefited collaterally from conservation such as habitat protection. We found that the difference conservation action makes to the conservation status of the world's ungulate species is likely to be higher than previously estimated. Increased, and sustained, investment could help achieve further improvements.

A case study of bats and white-nose syndrome demonstrating how to model population viability with evolutionary effects.

Ecological factors generally affect population viability on rapid time scales. Traditional population viability analyses (PVA) therefore focus on alleviating ecological pressures, discounting potential evolutionary impacts on individual phenotypes. Recent studies of evolutionary rescue (ER) focus on cases in which severe, environmentally induced population bottlenecks trigger a rapid evolutionary response that can potentially reverse demographic threats. ER models have focused on shifting genetics and resulting population recovery, but no one has explored how to incorporate those findings into PVA. We integrated ER into PVA to identify the critical decision interval for evolutionary rescue (DIER) under which targeted conservation action should be applied to buffer populations undergoing ER against extinction from stochastic events and to determine the most appropriate vital rate to target to promote population recovery. We applied this model to little brown bats (Myotis lucifugus) affected by white-nose syndrome (WNS), a fungal disease causing massive declines in several North American bat populations. Under the ER scenario, the model predicted that the DIER period for little brown bats was within 11 years of initial WNS emergence, after which they stabilized at a positive growth rate (λ = 1.05). By comparing our model results with population trajectories of multiple infected hibernacula across the WNS range, we concluded that ER is a potential explanation of observed little brown bat population trajectories across multiple hibernacula within the affected range. Our approach provides a tool that can be used by all managers to provide testable hypotheses regarding the occurrence of ER in declining populations, suggest empirical studies to better parameterize the population genetics and conservation-relevant vital rates, and identify the DIER period during which management strategies will be most effective for species conservation.

Migratory songbirds in the East Asian-Australasian Flyway: a review from a conservation perspective

SummaryThe East Asian-Australasian Flyway supports the greatest diversity and populations of migratory birds globally, as well as the highest number of threatened migratory species of any flyway, including passerines (15 species). However it is also one of the most poorly understood migration systems, and little is known about the populations and ecology of the passerine migrants that breed, stop over and winter in the habitats along this flyway. We provide the first flyway-wide review of diversity, ecology, and conservation issues relating to 170 species of long-distance and over 80 short-distance migrants from 32 families. Recent studies of songbird migration movements and ecology is limited, and is skewed towards East Asia, particularly Mainland China, Taiwan, Russia, Japan and South Korea. Strong evidence of declines exists for some species, e.g. Yellow-breasted BuntingEmberiza aureola, but tends to be fragmentary, localised or anecdotal for many others. More species have small breeding ranges (&lt; 250,000 km2) and/or are dependent on tropical forests as wintering habitat than those in any other Eurasian migratory system, and are thus more vulnerable to habitat loss and degradation throughout their ranges. Poorly regulated hunting for food and the pet trade, invasive species and collisions with man-made structures further threaten migratory songbirds at a number of stop-over or wintering sites, while climate change and habitat loss may be of increasing concern in the breeding ranges. A key conservation priority is to carry out intensive field surveys across the region while simultaneously tapping into citizen science datasets, to identify important stop-over and wintering sites, particularly for poorly-known or globally threatened species across South-East Asia and southern China for targeted conservation actions. Additionally, the advent of miniaturised tracking technology, molecular and isotopic techniques can provide novel insights into migration connectivity, paths and ecology for species in this migration system, complementing data from banding exercises and observation-based surveys, and could prove useful in informing conservation priorities. However, until most states along the East Asian-Australasian flyway ratify the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and other cross-boundary treaties, the relative lack of cross-boundary cooperation, coordination and information sharing in the region will continue to present a stumbling block for effective conservation of migratory passerines.

Factors Influencing Behavior and Success of Foraging Reddish Egrets (Egretta rufescens)

The Reddish Egret (Egretta rufescens) is the rarest and least studied species of heron in North America and is a species of conservation concern throughout its range. Foraging behavior and foraging success of the Reddish Egret were studied by focusing on whether their foraging behavior or success varied with age, color morph, group size, and habitat measures. Foraging individuals (n = 372) were video-recorded in the Laguna Madre of Texas, USA, from March 2008-April 2010. Adult Reddish Egrets were 30–250% more successful foragers than juveniles, and groups were 32–44% more successful foragers than solitary foragers. Foraging success was similar between color morphs. The more specialized foraging behaviors of canopy feeding, wing flicking, and foot-stirring had the highest success, but were employed infrequently. Four environmental variables (wind speed, light intensity, water depth, and percent seagrass coverage) were found to influence foraging success, but accounted for only 3% of the variation in foraging behavior. Our results suggest that environmental variables have little influence on foraging behavior of Reddish Egrets in the Laguna Madre, and we suggest that characteristics of the prey have a stronger influence. An understanding of how environmental variables influence foraging behavior and success may allow us to better assess habitat quality or possibly aid in identification of highly productive foraging sites and allow for more targeted conservation actions to those habitats that promote high foraging success.

Assessing multiregion avian benefits from strategically targeted agricultural buffers.

Mounting evidence of wildlife population gains from targeted conservation practices has prompted the need to develop and evaluate practices that are integrated into production agriculture systems and targeted toward specific habitat objectives. However, effectiveness of targeted conservation actions across broader landscapes is poorly understood. We evaluated multiregion, multispecies avian densities on row-crop fields with native grass field margins (i.e., buffers) as part of the first U.S. agricultural conservation practice designed to support habitat and population recovery objectives of a national wildlife conservation initiative. We coordinated breeding season point transect surveys for 6 grassland bird species on 1151 row-crop fields with and without native grass buffers (9-37 m) in 14 U.S. states (10 ecoregions) from 2006 to 2011. In most regions, breeding season densities of 5 of 6 targeted bird species were greater in the 500-m surrounding survey points centered on fields with native grass buffers than in landscapes without buffers. Relative effect sizes were greatest for Northern Bobwhite (Colinus virginianus), Dickcissel (Spiza americana), and Field Sparrow (Spizella pusilla) in the Mississippi Alluvial Valley and Eastern Tallgrass Prairie regions. Other species (e.g., Eastern Meadowlark [Sturnella magna], Grasshopper Sparrow [Ammodramus savannarum]) exhibited inconsistent relative effect sizes. Bird densities on fields with and without buffers were greatest in the Central Mixed-grass Prairie region. Our results suggest that strategic use of conservation buffers in regions with the greatest potential for relative density increases in target species will elicit greater range-wide population response than diffuse, uninformed, and broadly distributed implementation of buffers. We recommend integrating multiple conservation practices in broader agricultural landscapes to maximize conservation effectiveness for a larger suite of species.

Nest site selection of a primary hole‐nesting passerine reveals means to developing sustainable forestry

Anthropogenic habitat loss and fragmentation affect populations worldwide. For example, many bird populations of boreal forests have declined due to intensive forestry. To target conservation actions for such species, determining the key factors that affect their habitat selection is essential. Remote sensing methods provide highly potential means to measure habitat variables over large areas. We aim at identifying the key‐features of habitats by utilizing remote sensing data. As a case example, we study the nest site selection of a primary hole‐nesting passerine, the willow tit Poecile montanus, in a managed forest landscape. Using presence–absence data, we determine the most important habitat characteristics of the nest sites for three spatial scales by generalized linear mixed effect models. Our results highlight the importance of the availability of nesting sites – standing decaying deciduous trees – in the nest site selection of P. montanus. It seems to prefer moist habitats with high densities of deciduous trees and to avoid open areas, but does not require mature or intact habitats. Most of the nest site selection seems to occur within small scales. In this case, remote sensing data alone was insufficient for producing reliable models, but adding information of an ecologically important feature from direct field surveys greatly improved model performances. For the conservation and maintenance of dead wood dependent species, changes in forestry practices are necessary to keep the key characteristics of the habitat. Most importantly, continuous availability of standing decaying wood should be secured.

Phylogeographic evidence links the threatened ‘Grampians’ Mountain Dragon (Rankinia diemensis Grampians) with Tasmanian populations: conservation implications in south-eastern Australia

The importance of protecting genetic diversity within a species is increasingly being recognised by conservation management authorities. However, discrepancies in conservation policy between authorities, such as state versus national bodies, can have significant implications for species management when they cross state boundaries. We conducted a phylogeographic study of the south-eastern Australian lizard Rankinia diemensis to identify evolutionary significant units (ESUs), including the endangered population from the Grampians National Park in western Victoria. Phylogenetic analyses of two gene regions (mtDNA: ND2; nuclear: RAG1) revealed high levels of genetic divergence between populations, indicating isolation over long evolutionary time frames. Based on criteria of genetic divergence and isolation, R. diemensis contains at least two ESUs that require specific management. We found that R. diemensis from the Grampians are closely related to Tasmanian populations, but that the divergence between these regions is great enough (3.7 % mtDNA) that they should be considered separate ESUs. However, we believe the close evolutionary ties between these two regions needs to be taken into account; yet under current practises, conservation management of subspecific ESUs relies on state-level efforts. We argue that another population that occurs on the Victorian coast also qualifies as an ESU and requires targeted conservation action. Rankinia diemensis provides a case-in-point of the discrepancy between the state-level approach of maintaining genetic variation within a species and the more conservative Commonwealth focus on conserving biodiversity at the species level.

The conservation status of the world’s reptiles

Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles. Nearly one in five reptilian species are threatened with extinction, with another one in five species classed as Data Deficient. The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands, while data deficiency was highest in tropical areas, such as Central Africa and Southeast Asia, and among fossorial reptiles. Our results emphasise the need for research attention to be focussed on tropical areas which are experiencing the most dramatic rates of habitat loss, on fossorial reptiles for which there is a chronic lack of data, and on certain taxa such as snakes for which extinction risk may currently be underestimated due to lack of population information. Conservation actions specifically need to mitigate the effects of human-induced habitat loss and harvesting, which are the predominant threats to reptiles.

Distribution of duck broods relative to habitat characteristics in the Prairie Pothole Region

AbstractConservation programs for breeding ducks in the Prairie Pothole Region (PPR) of the United States and Canada require effective means of evaluating and characterizing breeding habitat across large landscapes. Extensive surveys of the distribution of duck broods in late‐summer could help identify wetland basins with greater probabilities of occupancy. Broods are difficult to detect, however, rendering presence–absence data from single‐visit surveys difficult to interpret, particularly when probability of detection is related to habitat features. Multiple‐visit occupancy surveys offer a potential solution. From 20 July to 5 August 2007–2009, we conducted a 3‐visit survey of wetland basins located on 167 10.4‐km2 study plots in the PPR. Our survey focused on broods of the 5 most common breeding duck species (Anas spp.). Our main objectives were to investigate ecological relationships between occupancy of wetland basins by broods and habitat characteristics and to examine if habitat‐specific detection was of enough concern to warrant multi‐survey approaches in the future. We surveyed 3,226 wetland basins during the study. Probability of occupancy of a wetland basin by a brood was positively related to the log of wet area for all 5 study species and was greater on wetlands located on plots with a greater proportion of herbaceous perennial cover for 4 of 5 species. For example, the median probability of occupancy for gadwall (Anas strepera) increased from 0.08 (90% Credible Interval [CrI]: 0.07, 0.10) to 0.28 (90% CrI: 0.23, 0.33) as wet area increased from 0.19 ha to 2.12 ha, and increased from 0.12 (90% CrI: 0.09, 0.16) to 0.20 (90% CrI: 0.16, 0.25) as proportion of perennial grass cover on the study plot increased from 0.03 to 0.99. Because occupancy and detection were both related to attributes of wetland basins, we concluded that the multiple‐visit survey was a useful approach for identifying habitat relationships of duck broods. Our results indicated that most broods of the study species were found in 10.4‐km2 landscapes with greater densities of small‐ to mid‐sized wetland basins and a greater proportion of herbaceous perennial vegetation. Our study provided new empirical support that could be used to help target conservation actions to the most productive landscapes for breeding ducks. © 2012 The Wildlife Society.

Predictions of ecological and social impacts of alternative residential development policies to inform decision making in a rural landscape

Anthropogenic landscape change has had a disproportionately large effect on temperate grassland systems. We used simulations of landscape change to compare the impacts of three commonly applied alternative residential development policies (protecting productive lands, growth boundaries, targeted protection of conservation lands) on ecological and socially important resources in a rural grassland landscape of northern Idaho, United States. Our simulations showed that development patterns were least socially acceptable and most detrimental to ecological resources under current land-use policies. Protecting productive agricultural lands led to the highest level of endangerment for remnant Palouse Prairie communities. Urban growth boundary policies produced the most socially acceptable development patterns and supported habitat for a wide range of species. Targeted conservation actions protected key habitat areas but did little to protect habitat for wide-ranging species. Detailed analyses such as these provide planners with the information required to assess and mitigate the consequences of policy decisions.

Genetic structure and connectivity among lake populations of threatened Paratherina sailfin silversides from Sulawesi, Indonesia

Spatially restricted endemic species are of special conservation concern as their narrow distributions render them particularly vulnerable to extinction through habitat loss. However, estimates of connectivity among populations can provide a basis for targeted conservation action. Here we quantify population genetic structure and connectivity for two endemic Sailfin silverside species within and among two lakes from the Malili Lakes, Indonesia. For both species, a greater proportion of genetic variance was found among sites within a lake than between lakes, indicative of riverine gene flow and cryptic genetic structure within the lakes. Bayesian genotype clustering revealed substantial population genetic structure within and among lakes, but also showed evidence of dispersal between lakes. These results are timely given the growing anthropogenic stressors in the Malili Lakes watershed, including mining and forestry operations.

Detection and quantification of the crayfish plague agent in natural waters: direct monitoring approach for aquatic environments

Aphanomyces astaci, a specialised parasite of North American freshwater crayfish, is the disease agent of crayfish plague that is lethal to European freshwater crayfish. The life cycle of A. astaci has been inferred from experimental laboratory studies, but less is known about its natural sustainability and ecology. To address such questions, tools for monitoring of A. astaci directly in aquatic environments are needed. Here, we present an approach for detecting and quantifying A. astaci directly from water samples using species-specific TaqMan minor groove binder real-time PCR. Samples of a 10-fold dilution series from approximately 10(4) to approximately 1 spore of A. astaci were repeatedly tested, and reliable detection down to 1 spore was demonstrated. Further, to simulate real-life samples from natural water bodies, water samples from lakes of various water qualities were spiked with spores. The results demonstrated that co-extracted humic acids inhibit detection significantly. However, use of bovine serum albumin or the TaqMan Environmental Master Mix largely removes this problem. The practical application of the approach was successfully demonstrated on real-life water samples from crayfish farms in Finland hosting infected North American signal crayfish Pacifastacus leniusculus. Direct monitoring of A. astaci from aquatic environments may find application in the management of wild noble crayfish Astacus astacus stocks, improved aquaculture practices and more targeted conservation actions. The approach will further facilitate studies of A. astaci spore dynamics during plague outbreaks and in carrier crayfish populations, which will broaden our knowledge of the biology of this devastating crayfish pathogen.

Conservation Implications of Drastic Reductions in the Smallest and Most Isolated Populations of Giant Pandas

In conservation biology, understanding the causes of endangerment is a key step to devising effective conservation strategies. We used molecular evidence (coalescent simulations of population changes from microsatellite data) and historical information (habitat and human population changes) to investigate how the most-isolated populations of giant pandas (Ailuropoda melanoleuca) in the Xiaoxiangling Mountains became highly endangered. These populations experienced a strong, recent demographic reduction (60-fold), starting approximately 250 years BP. Explosion of the human population and use of non-native crop species at the peak of the Qing Empire resulted in land-use changes, deforestation, and habitat fragmentation, which are likely to have led to the drastic reduction of the most-isolated populations of giant pandas. We predict that demographic, genetic, and environmental factors will lead to extinction of giant pandas in the Xiaoxiangling Mountains in the future if the population remains isolated. Therefore, a targeted conservation action--translocation--has been proposed and is being implemented by the Chinese government.

A method for spatial freshwater conservation prioritization

Summary1. Freshwater ecosystems are amongst the most threatened and poorly protected globally. They continue to be degraded through habitat loss, pollution and invading species and conservation measures are urgently needed to halt declining trends in their biodiversity and integrity.2. During the past decade a suite of decision support tools and computational approaches have been developed for efficient and targeted conservation action in terrestrial or marine ecosystems. These methods may be poorly suited for planning in freshwater systems because connectivity in terrestrial and marine systems is typically modelled in a way unsuitable for rivers, where connectivity has a strong directional component.3. We modify the conservation prioritization method and software, zonation, to account for connectivity in a manner better suited to freshwater ecosystems. Prioritization was performed using subcatchment/catchment‐based planning units and connectivity was modified to have directional upstream and downstream components consistent with the ecology of our target species.4. We demonstrate this modified method for rivers and streams in the southern North Island of New Zealand. Data included predicted occupancy from boosted regression tree models of species distributions for 18 fish species. The study area covered 2.1 million hectares and included 394 first‐ to fourth order catchment or subcatchment planning units.5. Realistic modelling of connectivity had a major influence on the areas proposed for conservation. If connectivity was ignored, recommended conservation areas were very fragmented. By contrast, when connectivity was modelled, high priority conservation targets consisted of entire river basins or headwater subcatchments.6. The proposed method serves as a starting point for the implementation of reserve selection methods in river ecosystems.

Mapping the Habitat Quality of Patch Networks for the Marsh Fritillary Euphydryas aurinia (Rottemburg, 1775) (Lepidoptera, Nymphalidae) in Wales

The marsh fritillary is widely distributed in Wales, with over 200 populations identified in the past 15 years. However, agricultural improvement, habitat fragmentation and changes in agricultural practices continue to impact on status and a decline in range of 23.5% was recorded over a 10-year period. Solutions must be applied at the landscape scale to improve metapopulation viability and, since 2000, surveys of habitat extent and quality have been carried out on 116,373 ha of grassland surrounding 111 populations. Analysis of the results for standard ‘core landscapes’ (based on circles of 1 km radius around known populations) shows that overall cover of suitable breeding habitat is 3.44%. However, only 11.85% of the grassland that was suitable for marsh fritillaries was classified as being in Good Condition. The remainder was regarded as having sub-optimal vegetation structure and/or the foodplant was at low density; 33% of the habitat resource that was not in Good Condition was regarded as inappropriately or excessively managed and 67% was suffering from neglect. An Index of Landscape Quality is used to rank landscapes for evaluation. Thirty-five ‘core landscapes’ (incorporating 98 marsh fritillary populations) were assessed and just four exceeded a threshold value deemed to represent viable landscape configurations. The results have demonstrated that most marsh fritillary populations in Wales exist within depauperate patch networks that lack sufficient breeding habitat of the right quality for long-term persistence. Without targeted conservation action the marsh fritillary will continue to decline in Wales. This paper reports on efforts to collect information on the quality of breeding habitat for marsh fritillaries across Wales in order to identify priorities for conservation action.