John M. Marzluff

Avian ecology and conservation in an urbanizing world

A shielding device is provided for protecting healthy tissue during radiotherapy of malignant tissue. The shielding device is composed of nontoxic, high atomic weight metal particles that are dispersed in a thermoplastic matrix material that is substantially rigid at temperatures encountered during radiotherapy, yet becomes readily moldable at temperatures that are within a comfortable range for a patient so as to enable in situ molding of the device. Because the matrix material is a nonsetting thermoplastic, the shielding device can be continuously reshaped in order to achieve a better fit for a patient and the radiation beam used. In addition, the shielding device can be readily reshaped in order to ensure an adequate thickness for radiation shielding.

Integrating Humans into Ecology: Opportunities and Challenges for Studying Urban Ecosystems

Abstract Our central paradigm for urban ecology is that cities are emergent phenomena of local-scale, dynamic interactions among socioeconomic and biophysical forces. These complex interactions give rise to a distinctive ecology and to distinctive ecological forcing functions. Separately, both the natural and the social sciences have adopted complex system theory to study emergent phenomena, but attempts to integrate the natural and social sciences to understand human-dominated systems remain reductionist—these disciplines generally study humans and ecological processes as separate phenomena. Here we argue that if the natural and social sciences remain within their separate domains, they cannot explain how human-dominated ecosystems emerge from interactions between humans and ecological processes. We propose an integrated framework to test formal hypotheses about how human-dominated ecosystems evolve from those interactions.

Worldwide urbanization and its effects on birds

Human populations are increasing and becoming predominantly urban. Resulting land cover changes reduce, perforate, isolate, and degrade bird habitat on local and global scales. I review: 1) urbanization of the Earth, and 2) published studies of bird responses to human settlement, and then: 3) suggest how and why birds respond to settlement. In a slight majority of studies, bird density increased, but richness and evenness decreased in response to urbanization. The most consistent effects of increasing settlement were increases in non-native species of birds, increases in birds able to nest on buildings (esp. swifts and swallows), increases in nest predation, and decreases in interior- and ground-nesting species. Effects of urbanization on hawks, owls, and cavity nesters were less consistent, in part being dependent on the surrounding habitat. The factors favoring species in urbanizing areas appear simpler than those reducing species. Increased availability of food was primary among factors benefiting species; predator reduction, reduced human persecution, and habitat enhancement were less important. Decreased habitat availability, reduced patch size, increased edge, increased non-native vegetation, decreased vegetative complexity, and increased nest predation were commonly associated with bird declines in response to human settlement. Urban planners and policy makers can profoundly affect how and where cities grow. Avian ecologists can help inform these important decisions by: 1) quantifying how the pattern of settlement affects birds and 2) understanding how bird populations and resulting communities change along entire gradients of urbanization.

RELATING RESOURCES TO A PROBABILISTIC MEASURE OF SPACE USE: FOREST FRAGMENTS AND STELLER'S JAYS

Many analytical techniques that assess resource selection focus on individual relocation points as the sample unit and classify resources as either used or available. Commonly, the relative use of each resource is quantified as the number of observations in each resource class or the proportional occurrence of a resource within a home range. We believe that a more accurate estimate can be summarized by a utilization distribution (UD). We present an analytical approach that explicitly incorporates a probabilistic measure of use, as defined by the UD. We used animal relocation points and fixed-kernel techniques to determine a UD within a home range. We related this probabilistic measure of use to categorical and continuous resource variables using multiple regression. Regression errors accounted for spatial autocorrelation so that the significance of regression coefficients could be appraised for each animal and averaged across animals. This allowed us to quantify the individualistic nature of resource sele...

Ecological resilience in urban ecosystems: Linking urban patterns to human and ecological functions

Urban ecosystems evolve over time and space as the outcome of dynamic interactions between socio-economic and biophysical processes operating over multiple scales. The ecological resilience of urban ecosystems—the degree to which they tolerate alteration before reorganizing around a new set of structures and processes—is influenced by these interactions. In cities and urbanizing areas fragmentation of natural habitats, simplification and homogenization of species composition, disruption of hydrological systems, and alteration of energy flow and nutrient cycling reduce cross-scale resilience, leaving systems increasingly vulnerable to shifts in system control and structure. Because varied urban development patterns affect the amount and interspersion of built and natural land cover, as well as the human demands on ecosystems differently, we argue that alternative urban patterns (i.e., urban form, land use distribution, and connectivity) generate varied effects on ecosystem dynamics and their ecological resilience. We build on urban economics, landscape ecology, population dynamics, and complex system science to propose a conceptual model and a set of hypotheses that explicitly link urban pattern to human and ecosystem functions in urban ecosystems. Drawing on preliminary results from an empirical study of the relationships between urban pattern and bird and aquatic macroinvertebrate diversity in the Puget Sound region, we propose that resilience in urban ecosystems is a function of the patterns of human activities and natural habitats that control and are controlled by both socio-economic and biophysical processes operating at various scales. We discuss the implications of this conceptual model for urban planning and design.

A historical perspective on urban bird research: trends, terms, and approaches

As Earth’s human population continues to increase and urbanize, it is likely to increasingly affect biodiversity. Avian ecologists have been studying these effects for over a century. Here, we review these studies to: 1) characterize the type of research approaches that have been used, 2) suggest strengths and weaknesses of these approaches, 3) offer a standardized nomenclature for the degree of settlement that will be used throughout this volume, and 4) suggest how our approach can be strengthened to better inform public policy. The majority of urban bird studies were conducted since 1980. The typical study is a one- or two-year correlational investigation of breeding bird relative abundance in the forests of the United States or northern Europe. Experimental studies are rare despite the frequent and replicated land transformations conducted by developers. Studies of birds in tropical, urban settings are especially rare. This is problematic because human populations are expected to rapidly grow and urbanize in such regions and biodiversity there is rich. Recognizing trade-offs among study duration, spatial extent, and mechanistic understanding, we suggest that researchers use short-term, correlational studies of the entire gradient of urbanization to inform long-term, mechanistic studies of bird populations. We define five points along the gradient of urbanization for consistent use throughout this volume (wildland, exurban or rural, suburban, and urban;(Table 1.1). These are useful for categorizing study areas at the landscape scale (>km2). Briefly, wildlands are unsettled lands that may occasionally include dwellings. Rural and exurban lands are sparsely settled by individual homesteads, recreational development, and small towns (they are distinguished by the surrounding matrix: rural = agricultural, exurban = native habitat). Suburban lands are characterized by moderate- to high-density, single-family housing with lot sizes of 0.1-1.0 ha. Urban lands are primarily covered by multi-family and/or multi-storied buildings. Urban bird studies would more effectively inform policy, planning, and management if they were more relevant, rigorous, compelling, and visible. We suggest that this can be accomplished by 1) understanding how development pattern affects birds, 2) increasing study of birds in tropical urban areas, 3) increasing the use of experimental, mechanistic investigations, 4) using landscape ecological metrics to quantify the urban settings we study, and 5) distilling clear graphs or photographs of important results.

Analysis of Resource Selection Using Utilization Distributions

Abstract Often resource selection functions (RSFs) are developed by comparing resource attributes of used sites to unused or available ones. We present alternative approaches to the analysis of resource selection based on the utilization distribution (UD). Our objectives are to describe the rationale for estimation of RSFs based on UDs, offer advice about computing UDs and RSFs, and illustrate their use in resource selection studies. We discuss the 3 main factors that should be considered when using kernel UD-based estimates of space use: selection of bandwidth values, sample size versus precision of estimates, and UD shape and complexity. We present 3 case studies that demonstrate use of UDs in resource selection modeling. The first example demonstrates the general case of RSF estimation that uses multiple regression adjusted for spatial autocorrelation to relate UD estimates (i.e., the probability density function) to resource attributes. A second example, involving Poisson regression with an offset term, is presented as an alternative for modeling the relative frequency, or probability of use, within defined habitat units. This procedure uses the relative frequency of locations within a habitat unit as a surrogate of the UD and requires relatively fewer user-defined options in the modeling of resource selection. Last, we illustrate how the UD can also be used to enhance univariate resource selection analyses, such as compositional analysis, in cases where animals use their range nonrandomly. The UD helps overcome several common shortcomings of some other analytical techniques by treating the animal as the primary sampling unit, summarizing use in a continuous and probabilistic manner, and relying on the pattern of animal space use rather than using individual sampling points. However, several drawbacks are apparent when using the UD in resource selection analyses. Choice of UD estimator is important and sensitive to sample size and user-defined options, such as bandwidth and software selection. Extensions to these procedures could consider behavioral-based approaches and alternative techniques to estimate the UD directly.

Island Biogeography for an Urbanizing World How Extinction and Colonization May Determine Biological Diversity in Human-Dominated Landscapes

Urbanization is increasing worldwide with potentially important implications to biological diversity. I show that bird diversity is responsive to the reduction of forest cover associated with urbanization in the Seattle, WA, USA metropolitan area. Bird diversity peaks at intermediate levels of human settlement primarily because of the colonization of intermediately disturbed forests by early successional, native species. Extinction of native forest birds and colonization of settlements by synanthropic birds have lesser effects on the overall pattern of avian diversity with respect to the level of urbanization. However, extinction increases linearly with loss of forest and colonization by synanthropic species decreases curvilinearly with reduction of urbanization. These findings have biological, theoretical, and practical implications. Biologically, intermediate disturbance appears to drive diversity by increasing the heterogeneity of the local land cover. Theoretically, I present a graphical model and use it to derive testable hypotheses about how extinction and colonization are affected by urbanization to determine local diversity. Practically, maintaining high local diversity without reducing regional or global diversity will require planning so that the same landscapes are not promulgated everywhere. This will require cooperation among a diverse group of planners, ecologists, policy makers, home owners, educators, and activists.

Effects of Tagging and Location Error in Wildlife Radiotelemetry Studies

Publisher Summary Important benefits of radio tagging of animals are the accuracy, precision, and completeness of resulting observations. Accurate inference in radiotelemetry depends on unbiased observations. Remotely gathered location estimates differ in precision and accuracy from visual observations. Moreover, behavior is influenced by the act of tagging or tracking. A fundamental assumption in wildlife studies reliant on radiotelemetry is that radio-tagged animals are “moving through the environment, responding to stimuli, and behaving in a manner similar to noninstrumented animals.” This chapter summarizes the effects of transmitters on wildlife, makes recommendations for studying and minimizing effects, and investigates the magnitude and implications of location error resulting from conventional transmitters. It also discusses the importance of conducting site-specific beacon tests to better understand bias and error in specific studies. The chapter encourages all researchers using radiotelemetry to conduct two studies before beginning with the collection of data on actual study subjects. First, the effects of the transmitter and method of transmitter attachment on the study species must be studied. Second, if animal locations are to be estimated remotely, a thorough beacon study in the actual field site under expected field conditions must be conducted. The goal of a beacon study is to produce a spatially explicit map of tracking accuracy for the study area and to quantify the precision and accuracy of the telemetry system.

Are the Smallest Organisms the Most Diverse

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