Matthias Leu

THE HUMAN FOOTPRINT IN THE WEST: A LARGE‐SCALE ANALYSIS OF ANTHROPOGENIC IMPACTS

Anthropogenic features such as urbanization, roads, and power lines, are increasing in western United States landscapes in response to rapidly growing human populations. However, their spatial effects have not been evaluated. Our goal was to model the human footprint across the western United States. We first delineated the actual area occupied by anthropogenic features, the physical effect area. Next, we developed the human footprint model based on the ecological effect area, the zone influenced by features beyond their physical presence, by combining seven input models: three models quantified top-down anthropogenic influences of synanthropic predators (avian predators, domestic dog and cat presence risk), and four models quantified bottom-up anthropogenic influences on habitat (invasion of exotic plants, human-caused fires, energy extraction, and anthropogenic wildland fragmentation). Using independent bird population data, we found bird abundance of four synanthropic species to correlate positively with human footprint intensity and negatively for three of the six species influenced by habitat fragmentation. We then evaluated the extent of the human footprint in relation to terrestrial (ecoregions) and aquatic systems (major rivers and lakes), regional management and conservation status, physical environment, and temporal changes in human actions. The physical effect area of anthropogenic features covered 13% of the western United States with agricultural land (9.8%) being most dominant. High-intensity human footprint areas (class 8-10) overlapped highly productive low-elevation private landholdings and covered 7% of the western United States compared to 48% for low-intensity areas (class 1-3), which were confined to low-productivity high-elevation federal landholdings. Areas within 1 km of rivers were more affected by the human footprint compared to lakes. Percentage human population growth was higher in low-intensity human footprint areas. The disproportional regional effects of the human footprint on landscapes in the western United States create a challenge to management of ecosystems and wildlife populations. Using footprint models, managers can plan land use actions, develop restoration scenarios, and identify areas of high conservation value at local landscapes within a regional context. Moreover, human footprint models serve as a tool to stratify landscapes for studies investigating floral and faunal response to human disturbance intensity gradients.

The potential importance of migratory stopover sites as flight feather molt staging areas: a review for neotropical migrants

The decline of many species of Neotropical migrants has prompted increased research on their ecology on their breeding and wintering grounds. However, studies of their ecology during migration are relatively few. Despite documentation of molt-migration in at least six Neotropical passerine species, this phenomenon has been ignored in current conservation strategies for Neotropical migrants. In this review paper, we suggest that molt studies need to be done as a way to refine and improve conservation plans for Neotropical migrants. We identify three important questions that merit further study: (1) which Neotropical migrant species undergo flight feather molt at migratory-stopover sites; (2) where are molt-migration stopover sites geographically located; and (3) why are these sites preferred as stopover sites during molt? Finding answers to these questions will allow us to protect molt staging areas occupied by Neotropical migrants during migration as many wetland and nearshore oceanic habitats have been protected for molting waterfowl, shorebirds, and seabirds.

Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data when the probability of detecting a species is <1. We use occupancy models to evaluate hypotheses concerning the occurrence and prevalence of B. dendrobatidis and discuss how this application differs from a conventional occupancy approach. We found that the probability of detecting the pathogen, conditional on presence of the pathogen in the anuran population, was related to amphibian development stage, day of the year, elevation, and human activities. Batrachochytrium dendrobatidis was found throughout our study area but was only estimated to occur in 53.4% of 78 populations of native amphibians and 66.4% of 40 populations of nonnative Rana catesbeiana tested. We found little evidence to support any spatial hypotheses concerning the probability that the pathogen occurs in a population, but did find evidence of some taxonomic variation. We discuss the interpretation of occupancy model parameters, when, unlike a conventional occupancy application, the number of potential samples or observations is finite.

Determining homology of molts and plumages to address evolutionary questions: a rejoinder regarding emberizid finches

Determining how molt is integrated into the annual cycle, and understanding what natural selection pressures have favored the diversity of molt strategies in birds are important issues in ornithology and zoology in general. To study these issues, most omithologists historically have used and continue to use many different nomenclatural systems which tie names of molts and plumages (e.g., breeding plumage, summer plumage, adult plumage) to events in the annual cycle, season or age. However, it is circular to study the evolution of molts and plumages in relation to annual cycle events, seasons or age because the definitions of plumages and molts in these systems are defined in terms of these parameters. To study the evolution of molts and plumages it is essential to use a system such as that proposed by Humphrey and Parkes (1959, 1963) to identify homologous molts and plumages that is independent of annual cycle events, seasons and age. This paper discusses how to use correctly the Humphrey-Parkes system and illustrates this by discussing an example of how the Humphrey-Parkes system was applied incorrectly in a series of studies on Passerina buntings. We also document that Phainopeplas, Phainopepla nitens, Yellowbreasted Chats, Icteria virens. Northern Cardinals, Cardinalis cardinalis, and Orange-breasted Buntings, Passerina leclancherii exhibit a previously unknown sequence of molts and plumages that is homologous to that of other recently studied Passerina species, and suggest that this sequence of molts and plumages probably is much more widespread in birds than is currently recognized.

Ecological scale of bird community response to piñon-juniper removal

Abstract Piñon (Pinus spp.) and juniper (Juniperus spp.) removal is a common management approach to restore sagebrush (Artemisia spp.) vegetation in areas experiencing woodland expansion. Because many management treatments are conducted to benefit sagebrush-obligate birds, we surveyed bird communities to assess treatment effectiveness in establishing sagebrush bird communities at study sites in Utah, Nevada, Idaho, and Oregon. Our analyses included data from 1 or 2 yr prior to prescribed fire or mechanical treatment and 3 to 5 yr posttreatment. We used detrended correspondence analysis to 1) identify primary patterns of bird communities surveyed from 2006 to 2011 at point transects, 2) estimate ecological scale of change needed to achieve treatment objectives from the relative dissimilarity of survey points to the ordination region delineating sagebrush bird communities, and 3) measure changes in pre- and posttreatment bird communities. Birds associated with sagebrush, woodlands, and ecotones were detected on our surveys; increased dissimilarity of survey points to the sagebrush bird community was characterized by a gradient of increased juniper and decreased sagebrush cover. Prescribed fires burned between 30% and 97% of our bird survey points. However, from 6% to 24% cover of piñon-juniper still remained posttreatment on the four treatment plots. We measured only slight changes in bird communities, which responded primarily to current vegetation rather than relative amount of change from pretreatment vegetation structure. Bird communities at survey points located at greater ecological scales from the sagebrush bird community changed least and will require more significant impact to achieve changes. Sagebrush bird communities were established at only two survey points, which were adjacent to a larger sagebrush landscape and following almost complete juniper removal by mechanical treatment. Our results indicate that management treatments that leave residual woodland cover and are not adjacent to extensive sagebrush stands are unlikely to establish sagebrush birds.

Taking the health aid debate to the subnational level: the impact and allocation of foreign health aid in Malawi

Objective Cross-national studies provide inconclusive results as to the effectiveness of foreign health aid. We highlight a novel application of using subnational data to evaluate aid impacts, using Malawi as a case study. Design We employ two rounds of nationally representative household surveys (2004/2005 and 2010/2011) and geo-referenced foreign aid data. We examine the determinants of Malawis traditional authorities receiving aid according to health, environmental risk, socioeconomic and political factors. We use two approaches to estimate the impact of aid on reducing malaria prevalence and increasing healthcare quality: difference-in-difference models, which include traditional authority and month-of-interview fixed effects and control for individual and household level time-varying factors, and entropy balancing, where models balance on health-related and socioeconomic baseline characteristics. General health aid and four specific health aid sectors are examined. Results Traditional authorities with greater proportions of individuals living in urban areas, more health facilities and greater proportions of those in major ethnic groups were more likely to receive aid. Difference-in-difference models show health infrastructure and parasitic disease control aid reduced malaria prevalence by 1.20 (95% CI −0.36 to 2.76) and 2.20 (95% CI 0.43 to 3.96) percentage points, respectively, and increased the likelihood of individuals reporting healthcare as more than adequate by 12.1 (95% CI 1.51 to 22.68) and 14.0 (95% CI 0.11 to 28.11) percentage points. Entropy balancing shows similar results. Conclusions Aid was targeted to areas with greater existing health infrastructure rather than areas most in need, but still effectively reduced malaria prevalence and enhanced self-reported healthcare quality.

Diffuse migratory connectivity in two species of shrubland birds: evidence from stable isotopes

Abstract Connecting seasonal ranges of migratory birds is important for understanding the annual template of stressors that influence their populations. Brewer’s sparrows (Spizella breweri) and sagebrush sparrows (Artemisiospiza nevadensis) share similar sagebrush (Artemisia spp.) habitats for breeding but have different population trends that might be related to winter location. To link breeding and winter ranges, we created isoscapes of deuterium [stable isotope ratio (δ) of deuterium; δ2H] and nitrogen (δ15N) for each species modeled from isotope ratios measured in feathers of 264 Brewer’s and 82 sagebrush sparrows and environmental characteristics at capture locations across their breeding range. We then used feather

Incorporating Wildlife Conservation into County Comprehensive Plans: A GIS Approach

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