Environmental Determinants of Recent Endemism of Batrachochytrium dendrobatidis Infections in Amphibian Assemblages in the Absence of Disease Outbreaks

The inconsistent distribution of large‐scale infection mediated die‐offs and the subsequent population declines of several animal species, urges us to understand how, when, and why species are affected by disease. It is often unclear when or under what conditions a pathogen constitutes a threat to a host. Often, variation of environmental conditions plays a role. Globally Batrachochytrium dendrobatidis (Bd) causes amphibian declines; however, host responses are inconsistent and this fungus appears equally capable of reaching a state of endemism and subsequent co‐existence with native amphibian assemblages. We sought to identify environmental and temporal factors that facilitate host–pathogen coexistence in northern Europe. To do this, we used molecular diagnostics to examine archived and wild amphibians for infection and general linear mixed models to explore relationships between environmental variables and prevalence of infection in 5 well‐sampled amphibian species. We first detected infection in archived animals collected in 1999, and infection was ubiquitous, but rare, throughout the study period (2008–2010). Prevalence of infection exhibited significant annual fluctuations. Despite extremely rare cases of lethal chytridiomycosis in A. obstetricans, Bd prevalence was uncorrelated with this species’ population growth. Our results suggest context dependent and species‐specific host susceptibility. Thus, we believe recent endemism of Bd coincides with environmentally driven Bd prevalence fluctuations that preclude the build‐up of Bd infection beyond the critical threshold for large‐scale mortality and host population crashes. Determinantes Ambientales del Endemismo Reciente de Infecciones de Batrachochytrium dendrobatidis en Conjuntos de Anfibios en Ausencia de Brotes de Enfermedades Spitzen et al.     

Microcomputers in the Third World: Recommendations for Use in Water Resources

The paper provides an introduction for professionals in the water resources field who are considering the use of a microcomputer in their work. The types of hardware and software available are discussed, as well as the factors which should be considered in choosing an appropriate system. Two microcomputer systems are suggested, an 'ideal' and a 'minimum', along with some indicative prices.     

Assessing the Effects of Climate Change on Aquatic Invasive Species

Abstract:  Different components of global environmental change are typically studied and managed independently, although there is a growing recognition that multiple drivers often interact in complex and nonadditive ways. We present a conceptual framework and empirical review of the interactive effects of climate change and invasive species in freshwater ecosystems. Climate change is expected to result in warmer water temperatures, shorter duration of ice cover, altered streamflow patterns, increased salinization, and increased demand for water storage and conveyance structures. These changes will alter the pathways by which non-native species enter aquatic systems by expanding fish-culture facilities and water gardens to new areas and by facilitating the spread of species during floods. Climate change will influence the likelihood of new species becoming established by eliminating cold temperatures or winter hypoxia that currently prevent survival and by increasing the construction of reservoirs that serve as hotspots for invasive species. Climate change will modify the ecological impacts of invasive species by enhancing their competitive and predatory effects on native species and by increasing the virulence of some diseases. As a result of climate change, new prevention and control strategies such as barrier construction or removal efforts may be needed to control invasive species that currently have only moderate effects or that are limited by seasonally unfavorable conditions. Although most researchers focus on how climate change will increase the number and severity of invasions, some invasive coldwater species may be unable to persist under the new climate conditions. Our findings highlight the complex interactions between climate change and invasive species that will influence how aquatic ecosystems and their biota will respond to novel environmental conditions.     

Effects of Harvesting Flowers from Shrubs on the Persistence and Abundance of Wild Shrub Populations at Multiple Spatial Extents

Abstract: Wildflower harvesting is an economically important activity of which the ecological effects are poorly understood. We assessed how harvesting of flowers affects shrub persistence and abundance at multiple spatial extents. To this end, we built a process‐based model to examine the mean persistence and abundance of wild shrubs whose flowers are subject to harvest (serotinous Proteaceae in the South African Cape Floristic Region). First, we conducted a general sensitivity analysis of how harvesting affects persistence and abundance at nested spatial extents. For most spatial extents and combinations of demographic parameters, persistence and abundance of flowering shrubs decreased abruptly once harvesting rate exceeded a certain threshold. At larger extents, metapopulations supported higher harvesting rates before their persistence and abundance decreased, but persistence and abundance also decreased more abruptly due to harvesting than at smaller extents. This threshold rate of harvest varied with species’ dispersal ability, maximum reproductive rate, adult mortality, probability of extirpation or local extinction, strength of Allee effects, and carrying capacity. Moreover, spatial extent interacted with Allee effects and probability of extirpation because both these demographic properties affected the response of local populations to harvesting more strongly than they affected the response of metapopulations. Subsequently, we simulated the effects of harvesting on three Cape Floristic Region Proteaceae species and found that these species reacted differently to harvesting, but their persistence and abundance decreased at low rates of harvest. Our estimates of harvesting rates at maximum sustainable yield differed from those of previous investigations, perhaps because researchers used different estimates of demographic parameters, models of population dynamics, and spatial extent than we did. Good demographic knowledge and careful identification of the spatial extent of interest increases confidence in assessments and monitoring of the effects of harvesting. Our general sensitivity analysis improved understanding of harvesting effects on metapopulation dynamics and allowed qualitative assessment of the probability of extirpation of poorly studied species.     

Differences in Predators of Artificial and Real Songbird Nests: Evidence of Bias in Artificial Nest Studies

Abstract:  In the past two decades, many researchers have used artificial nests to measure relative rates of nest predation. Recent comparisons show that real and artificial nests may not be depredated at the same rates, but no one has examined the mechanisms underlying these patterns. We determined differences in predator-specific predation rates of real and artificial nests. We used video cameras to monitor artificial nests baited with quail and plasticine eggs and Field Sparrow ( Spizella pusilla ) and Indigo Bunting ( Passerina cyanea ) nests in field habitats in central Missouri (U.S.A.). Although daily predation estimates (all predators pooled) were similar between artificial and real nests, predators differed substantially in their depredation of artificial versus real nests. Snakes were the major predator at real nests, and raccoons ( Procyon lotor) were the major predator at artificial nests. We found strong support for models that distinguished predation between two or among three predator groups and between artificial and real nests. There was no snake predation of artificial nests, and the odds of predation of artificial nests was 115–551% (95% confidence interval) and 2–154% of the odds of predation of real nests by mammals and birds, respectively. Artificial nests with plasticine eggs could not be used reliably to identify predators. In several cases plasticine eggs were marked by mice, and raccoons were recorded on video removing the quail egg. Because biases for artificial nests were positive for some predators and negative for other predators (and could be compensating), and potentially existed for all predator groups, conclusions based on artificial nest studies should be suspect even when there is evidence that overall predation rates are similar among real and artificial nests.     

Virtual Corridors for Conservation Management

Abstract:  Corridors are usually perceived as clearly visible, linear landscape elements embedded in a hostile environment that connect two or more larger blocks of habitat. Animal response to certain aspects of landscape heterogeneity, however, can channel their movements into specific routes that may appear similar to their surroundings. These routes can be described as "virtual corridors" (VCs). Here we contribute to the foundation of the concept of VCs and highlight their implications for conservation management. We used an individual-based model to analyze the formation of VCs in the case of hilltopping in butterflies—where males and virgin females ascend to hilltops and mate. We simulated butterfly movements in two different topographically heterogeneous landscapes. We analyzed the movement patterns with respect to one parameter, the intensity of response to topography. Virtual corridor structure depended on the behavioral parameter, landscape, and location of the source patch. Within a realistic range of the behavioral parameter and in a realistic landscape, VC structures may be complex and require individual-based models for their elucidation.     

Efficacy of Two Lion Conservation Programs in Maasailand,Kenya

Lion (Panthera leo) populations are in decline throughout most of Africa. The problem is particularly acute in southern Kenya, where Maasai pastoralists have been spearing and poisoning lions at a rate that will ensure near term local extinction. We investigated 2 approaches for improving local tolerance of lions: compensation payments for livestock lost to predators and Lion Guardians, which draws on local cultural values and knowledge to mitigate livestock‐carnivore conflict and monitor carnivores. To gauge the overall influence of conservation intervention, we combined both programs into a single conservation treatment variable. Using 8 years of lion killing data, we applied Manski's partial identification approach with bounded assumptions to investigate the effect of conservation treatment on lion killing in 4 contiguous areas. In 3 of the areas, conservation treatment was positively associated with a reduction in lion killing. We then applied a generalized linear model to assess the relative efficacy of the 2 interventions. The model estimated that compensation resulted in an 87–91% drop in the number of lions killed, whereas Lion Guardians (operating in combination with compensation and alone) resulted in a 99% drop in lion killing. Eficacia de Dos Programas de Conservación de Leones en Maasailand, Kenia     

Using Cost‐Effective Targeting to Enhance the Efficiency of Conservation Investments in Payments for Ecosystem Services

Abstract: Ecosystem services are being protected and restored worldwide through payments for ecosystem services in which participants are paid to alter their land‐management approaches to benefit the environment. The efficiency of such investments depends on the design of the payment scheme. Land features have been used to measure the environmental benefits of and amount of payment for land enrollment in payment for ecosystem services schemes. Household characteristics of program participants, however, may also be important in the targeting of land for enrollment. We used the characteristics of households participating in China's Grain‐to‐Green program, and features of enrolled land to examine the targeting of land enrollment in that program in Wolong Nature Reserve. We compared levels of environmental benefits that can be obtained through cost‐effective targeting of land enrollment for different types of benefits under different payment schemes. The efficiency of investments in a discriminative payment scheme (payments differ according to opportunity costs, i.e., landholders’ costs of forgoing alternative uses of land) was substantially higher than in a flat payment scheme (same price paid to all participants). Both optimal targeting and suboptimal targeting of land enrollment for environmental benefits achieved substantially more environmental benefits than random selection of land for enrollment. Our results suggest that cost‐effective targeting of land through the use of discriminative conservation payments can substantially improve the efficiency of investments in the Grain‐to‐Green program and other payment for ecosystem services programs.     

Limiting Depredation by African Carnivores: the Role of Livestock Husbandry

Abstract:   Most large carnivore species are in global decline. Conflict with local people, particularly over depredation on livestock, is a major cause of this decline, affecting both nominally protected populations and those outside protected areas. For this reason, techniques that can resolve conflicts between large carnivores and livestock farmers may make important contributions to conservation. We monitored rates of livestock depredation by lions (  Panthera leo ), leopards ( Panthera pardus ), cheetahs ( Acinonyx jubatus ), and spotted hyenas ( Crocuta crocuta ), and retributive killing of these species by farmers in livestock-producing areas of Laikipia District, Kenya. Farmers killed more lions, leopards, and spotted hyenas where these predators killed more livestock. Livestock husbandry had a clear effect on rates of depredation and hence on the numbers of predators killed. Cattle, sheep, and goats experienced the lowest predation rates when attentively herded by day and enclosed in traditional corrals (bomas) by night. Construction of the boma, the presence of watchdogs, and high levels of human activity around the boma were all associated with lower losses to predators. Although most of this work was carried out on commercial ranches, local Maasai and Samburu pastoralists have practiced nearly identical forms of husbandry for generations. Our study shows that traditional, low-tech husbandry approaches can make an important contribution to the conservation of large carnivores.