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Publications (94)
Arctic and boreal environments are changing rapidly, which could decouple behavioral and demographic traits of animals from the resource pulses that have shaped their evolution. Dall’s sheep (Ovis dalli dalli) in northwestern regions of the USA and Canada, survive long, severe winters and reproduce during summers with short growing seasons. We soug...
Marine birds in Alaska, USA, have been monitored systematically for more than 4 decades, and yet it remains unclear why some populations have increased while others have declined. We analyzed the population dynamics of 5 seabird species-Black-legged (Rissa tridactyla) and Red-legged kittiwakes (R. brevirostris), Common (Uria aalge) and Thick-billed...
Declining populations of greater sage-grouse (Centrocercus urophasianus; hereafter, sage-grouse) necessitate accurate estimates of population trends. The most widespread approach to monitoring sage-grouse populations involves counting males attending leks and tracking changes across years. Visibility of male sage-grouse on leks is likely <100% for...
Context
Distance sampling is used to estimate abundance for several taxa, including pronghorn (Antilocapra americana). Comparisons between population estimates derived from quadrat sampling and distance sampling suggest that distance sampling underestimates pronghorn density, likely owing to violations of the critical assumption of distance samplin...
Migration is an important component of the life history of many animals, but persistence of large-scale terrestrial migrations is being challenged by environmental changes that fragment habitats and create obstacles to animal movements. In northern Alaska, the Central Arctic herd (CAH) of barren-ground caribou (Rangifer tarandus granti) is known to...
Animation of seasonal movements of one caribou in northern Alaska during 2004.
The caribou moved from the wintering area from 2003/2004, followed the spring migration route to the calving area and summer range and then followed the fall migration route back to its 2004/2005 winter range.
(ZIP)
We estimated the population growth rates of Bull Trout Salvelinus confluentus and used population growth models to evaluate observation error and estimate Bull Trout persistence probabilities by using 25 data sets (averaging 19 years of record) that indexed abundance across Idaho. These data sets were derived from a variety of fish sampling techniq...
Royle, J. A., R. B. Chandler, R. Sollmann, and B. Gardner. 2014. Spatial Capture–Recapture. Academic Press, Waltham, Massachusetts, 577 pp. ISBN 978-0-12-405939-9, price (paper), $129.95.
Wildlife managers are challenged to manage spatially structured populations efficiently and effectively, therefore dispersal and gene flow are vital to understand and manage, particularly for a harvested species. We used a genetic approach to describe the metapopulation structure of Rocky Mountain elk (Cervus elaphus) in Idaho to assess past patter...
Conservation and management of Alaska’s caribou (Rangifer tarandus granti) herds are important for ecological, cultural, social, and economic reasons. While most research is directed towards the large migratory herds, smaller herds that may or may not be migratory can be an equally valuable component of the state’s faunal resources; but for many of...
Population sex ratio is an important metric for wildlife management and conservation, but estimates can be difficult to obtain, particularly for sexually monomorphic species or for species that differ in detection probability between the sexes. Noninvasive genetic sampling (NGS) using polymerase chain reaction (PCR) has become a common method for i...
Habitat selection fundamentally drives the distribution of organisms across landscapes; density-dependent habitat selection (DDHS) is considered a central component of ecological theories explaining habitat use and population regulation. A preponderance of DDHS theories is based on ideal distributions, such that organisms select habitat according t...
QuestionWhat is the composition of vegetation communities found across mountain goat ranges? Can we use LandSat 5TM to model those vegetation communities across a mountain range to guide conservation and management plans? LocationThe Cascade Mountains of Washington, USA. Methods
We surveyed vegetation across previously undocumented home ranges of m...
We studied gray wolf (Canis lupus) homesite attendance rates using global positioning system locations of 17 GPS-radiocollared wolves from 7 packs in Idaho. Nonbreeding wolves attended homesites more once pups were weaned and we hypothesize this is a behavior that benefits subsequent pup-rearing. The breeding status and sex of the wolf was the stro...
multiple use management of the Nation’s forest resources for sustained yields of wood, water, forage, wildlife, and recreation. Through forestry research, cooperation with the States and private forest owners, and management of the National Forests and National Grasslands, it strives—as directed by Congress—to provide increasingly greater service t...
1. Climate change models consistently predict snow depth declines across the Northern Hemisphere. Snow depth has been linked to the demography of numerous species, and snow depth reduction is expected to affect the demography of some northern species. As many demographic studies depend on long-term population data that extend back beyond available...
Unbiased estimates of burrowing owl populations (Athene cunicularia) are essential to achieving diverse management and conservation objectives. We conducted visibility trials and developed logistic regression models to identify and correct for visibility bias associated with single, vehicle-based, visual survey occasions of breeding male owls durin...
Manipulating predator populations is often posed as a solution to depressed ungulate populations. However, predator–prey dynamics are complex and the effect on prey populations is often an interaction of predator life history, climate, prey density, and habitat quality. The effect of predator removal on ungulate and, more specifically, mule deer (O...
A study was conducted to analyze Greater Sage-Grouse (Centrocercus urophasianus) populations throughout the species' range by accumulating and estimating counts of males at 9,870 leks identified since 1965. A substantial number of leks are censused each year throughout North America providing a combined total of 75,598 counts through 2007, with man...
Recent analyses of Greater Sage-Grouse (Centrocercus urophasianus) populations indicate substantial declines in many areas but relatively stable populations in other portions of the species' range. Sagebrush (Artemisia spp.) habitats necessary to support sage-grouse are being burned by large wildfires, invaded by nonnative plants, and developed for...
Forested buffer strips are used to mitigate fragmentation and habitat loss and are a common feature in management of riparian landscapes. Low-elevation, old-growth coastal forests are a rare riparian habitat that can benefit from similar conservation measures. We evaluated the effectiveness of postlogging, forested buffer strips for forest-dwelling...
Genetic monitoring has rarely been used for wildlife translocations despite the potential benefits this approach offers, compared to traditional field-based methods. We applied genetic monitoring to the reintroduced brown bear population in northern Italy. From 2002 to 2008, 2781 hair and faecal samples collected noninvasively plus 12 samples obtai...
During the 1999 and 2000 spring and summer seasons, we collected and analyzed 544 eggs, 273 from background sites and 271 from mining sites to measure and compare selenium (Se) levels. We collected and analyzed eggs from 31 avian species. Our data indicated an increase in Se levels in birds on mining sites, i.e., 16 of 24 species (67%) had signific...
We investigated survival and cause-specific mortality of mule deer (Odocoileus hemionus) on 3 distinct winter ranges in southwest Idaho from 1992 to 1997 to identify demographic variation and potential limiting factors based on a sample of 447 radiocollared deer. During winters 1995–1996 and 1996–1997, we modeled overwinter fawn mortality based on...
Logs are an important structural feature of forest ecosystems, and their abundance affects many resources and forest processes, including fire regimes, soil productivity, silviculture, carbon cycling, and wildlife habitat. Consequently, logs are often sampled to estimate their frequency, percent cover, volume, and weight. The line-intersect method...
Se ha descrito que el hábitat de anidación de Accipiter gentilis en América del Norte está asociado con la cantidad de bosque maduro de dosel cerrado en el área de anidación. Sin embargo, pocos estudios han puesto a prueba experimentalmente los efectos de la extracción de madera sobre la reproducción de esta especie. Evaluamos los efectos de la tal...
The Apennine brown bear (Ursus arctos marsicanus) is an endangered subspecies endemic to Italy, where a small population, estimated at 40-50 bears, inhabits a human-dominated landscape. Although little is known of the ecology of this population, habitat loss and fragmentation often has been considered one of the main threats for small and endangere...
We describe sampling methods and provide software to accurately and efficiently estimate snag and tree densities at desired scales to meet a variety of research and management objectives. The methods optimize sampling effort by choosing a plot size appropriate for the specified forest conditions and sampling goals. Plot selection and data analyses...
We propose a simple multivariate model for describing and understanding animal space use that estimates an animal's probability of occurrence as an explicit function of the animal's association with a fixed spatial area (i.e., home range), the spatial distribution of resources within that area, and the occurrence of other animals. We begin with a n...
The Natura 2000 network is the most important conservation effort being implemented in Europe. Nevertheless, no comprehensive and systematic region-or nationwide evaluation of the effectiveness of the network has been conducted. We used habitat suitability models and extent of occurrence of 468 species of vertebrates to evaluate the contribution of...
Despite an abundance of studies describing nest selection in cavity-nesting birds, few account for the variation in habitat availability across the geographic range of a species and through time. Changes in the frequency of disturbances such as fires, timber harvests, and insect outbreaks can dramatically alter habitat. Responses by cavity-nesting...
By studying animal movements, researchers can gain insight into many of the ecological characteristics and processes important for understanding population-level dynamics. We developed a Brownian bridge movement model (BBMM) for estimating the expected movement path of an animal, using discrete location data obtained at relatively short time interv...
ABSTRACT Fixed-kernel density estimates using radiotelemetry locations are frequently used to quantify home ranges of animals, interactions, and resource selection. However, all telemetry data have location error and no studies have reported the effects of error on utilization distribution and area estimates using fixed-kernel density estimators. W...
Home-range models implicitly assume equal observation rates across the study area. Because this assumption is frequently violated, we describe methods for correcting home-range models for observation bias. We suggest corrections for 3 general types of home-range models including those for which parameters are estimated using least-squares theory, m...
Global positioning system (GPS) technology enables researchers to evaluate wildlife movements, space use and resource selection in detail for extended periods of time. Two types of errors, missed location fixes and location error, are inherent to GPS telemetry and can bias location data sets. Habitat characteristics can influence both types of erro...
Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, var...
Choosing an appropriate home range model is important for describing space use by animals and understanding the ecological processes affecting animal movement. Traditional approaches for choosing among home range models have not resulted in general, consistent, and unambiguous criteria that can be applied to individual data sets. We present a new a...
2005: Exploitation and greater sage-grouse Centrocercus urophasianus: a response to Sedinger and Rotella. -Wildl. Biol. 11: 377-381. Associate Editor: Jan Lindström Recently, Sedinger & Rotella (2005) offered an insight-ful critique of our paper on the response of greater sage-grouse Centrocercus urophasianus populations to differ-ent levels of exp...
Accurate estimation of the characteristics of log resources, or coarse woody debris (CWD), is critical to effective management of wildlife and other forest resources. Despite the importance of logs as wildlife habitat, methods for sampling logs have traditionally focused on silvicultural and fire applications. These applications have emphasized est...
We investigated the response of greater sage-grouse Centrocercus urophasianus populations to different levels of exploitation. From 1995 through 2002 we monitored breeding populations in areas closed to hunting, open to limited hunting (1-bird daily bag limit; 7-day season), and open to moderate hunting (2-bird daily bag limit; 23-day season). We u...
One of the primary challenges in spatial analysis is the sensitivity of statistical results to the definition of spatial units over which data are collected. In the geographical literature, this sensitivity is known as the modifiable areal unit problem (MAUP), and results have been shown to vary with both the level and the configuration of aggregat...
We developed efficient and accurate methods for sampling snags and large trees important to wildlife. These methods are described in detail in a recent Forest Service publication, which also includes spreadsheets, macros, and instructions to conduct surveys and analyses to estimate densities and distributions of snags and large trees on a landscape...
In 1998 we initiated a long-term study investigating the relationships between woodpecker foraging and snag decay processes in interior ponderosa pine forest communities located in Oregon and California. We describe temporal changes in snag structure and quantify both woodpecker foraging activity and relative sapwood decay in 144 ponderosa pine sna...
Design studies that use radiotelemetry require careful consideration of the goals of a project and the resources available to meet those goals. Success in meeting the research goals depends on thoughtful planning of field methods and ancillary data collection, selection of telemetry equipment appropriate to the study animal and budget, careful exec...
Assessing resource selection is one of the main objectives of many wildlife radiotelemetry studies. Methods for determining resource selection vary from the widely used χ2 analysis for categorical data to complex statistical modeling using continuous data. This chapter conducts an evaluation with elk location data generated from an automated tracki...
We compared avian use of 39 restored and 39 natural wetlands in North and South Dakota during spring and summer of 1997 and 1998. Wetlands were widely distributed, but restored- and natural-wetland pairs were from the same geographic locale and had similar characteristics, including wetland size. We conducted paired comparisons between restored and...
Nutritional stress is an important mortality factor for wintering mule deer (Odocoileus hemionus hemionus Rafinesque), particularly fawns. The rate at which fawns utilize existing fat stores is at least partially dependent upon the quality of available forage during winter. Although numerous studies have determined the nutritive value of various fo...
Recovery planning for imperiled populations of anadromous salmonids can require estimates of the carrying capacity of a river for redds (hereafter, redd capacity). We estimated redd capacity for the 106 known fall chinook salmon spawning sites in the upper and lower reaches of the Snake River. We used a modification of the Instream Flow Incremental...
Researchers have come to different conclusions about the usefulness of habitat-relationship models for predicting species presence or absence. This difference frequently stems from a failure to recognize the effects of spatial scales at which the models are applied. We examined the effects of model complexity, spatial data resolution, and scale of...
1 Introduction 4 General Information 4 Files Online 4 Sampling Applications 5 General Snag and Large Tree Sampling Guidelines 5 Landscape Definition and Selection 5 Sampling Objectives 6 Landscape Stratification 8 Methods 8 General Surveying Procedures 9 Establishing Transects 12 Plot Size Selection 14 Snag and Large Tree Survey Techniques 16 Compu...
Habitat management for bull and cow elk (Cervus elaphus nelsoni) may require different forest management standards because of likely sexual differences in distribution and habitat selection patterns. Current standards are based on the habitat use patterns of cow elk. Thus, we located 121 radiocollared elk (101 bulls, 20 cows) 4,527 times in the for...
Recovery of rodent bone and teeth from coyote (Canis latrans) scats (feces) varied with prey size, meal size, energy content of the meal, and the frequency with which prey were consumed. Mean percentages of mouse and rat teeth recovered ranged from 1% (SE = 0.5%, n = 5) to 24.4% (SE = 3.6%, n = 4) and from 13.8% (SE = 3.8%, n = 5) to 52.5% (SE = 16...
Visibility bias (failure to observe all animals) encountered during aerial surveys produces biased estimates of population parameters. The authors measured visibility bias for helicopter surveys of bighorn sheep (Ovis canadensis) in SW Idaho. Visibility was influenced by activity, habitat, sex composition of groups, light condition, position of she...
Habitat condition and hunter density may affect mortality rates of elk (Cervus elaphus), and therefore, the amount of recreational opportunity offered hunters. Thus, we radio-monitored 121 elk in the forested habitats of northcentral Idaho during 1986-91 to determine cause-specific mortality. Sixty-nine deaths recorded during this period included:...
Age and sex ratio statistics are often a key component of the evaluation and management of wildlife populations. These statistics are determined from counts of animals that are commonly plagued by errors associated with either survey design or visibility bias. We present age and sex ratio estimators that incorporate both these sources of error and...
We studied resource partitioning among the forest owls in the River of No Return Wilderness, Idaho, during the winter and spring of 1980 and 1981. The owl assemblage consisted of five abundant species: pygmy (Glaucidium gnoma), saw-whet (Aegolius acadicus), boreal (A. funereus), western screech (Otus kennicottii), and great-horned (Bubo virginianus...
Radio-collared elk (Cervus elaphus) were used to assess the importance of visibility factors during winter helicopter surveys in northcentral Idaho. Radio collars facilitated monitoring elk groups to determine whether elk were observed or missed during helicopter counts. Multivariate analysis indicated that visibility was significantly influenced b...
The variable circular plot (VCP) method for censusing animals is used widely to estimate the abundance of forest birds, despite a lack of effective methods for analyzing such data. By transforming the detection distances to areas, the efficient, robust procedures developed for analyzing line transect data may be successfully applied to VCP data in...
The amount of time an animal spends in particular areas is an important aspect of estimating its home range and activity pattern. Calculations of home range using the harmonic mean can be modified to reflect the amount of time or the type of activity observed at each location. The relative time spent at each location may be used to calculate a time...
We compared principal components derived from sets of real data with dimensions of 120 x 7, 120 x 4, 150 x 11, 150 x 8, 150 x 5, 454 x 12, 454 x 8, and 454 x 5, to those from sets of randomly generated data of corresponding size. Principal components from subsets of 25, 50, 75, and 100 observations from the 120- and 150-observation data sets and th...
(1) Animals generally use space disproportionately within the boundaries of their home range. Areas receiving concentrated use by resident animals can be termed core areas. Identifying these core areas is an important part of understanding the ecological factors that determine use. (2) Comparison of the observed space-use pattern with that expected...
A robust estimation procedure is proposed to identify and reduce the influence of extreme locations for the bivariate normal home-range method. Tests are proposed for validating the underlying probability distribution from observed animal locations. Location data from a black bear (Ursus americanus) are used to demonstrate the effect of outliers on...
Birds consume large numbers of the western spruce budworm (Choristoneura occidentalis), a forest insect which defoliates economically valuable stands. We estimated the economic value of bird predation on two stands in north-central Washington by substituting the cost to spray with insecticides to produce the same mortality rate as birds cause. It w...
Optimal foraging theory is useful in understanding foraging behavior of insectivorous forest birds. The theory correctly predicts qualitative changes in dietary specialization and allocation of foraging time observed in experimental and field studies. It suggests that forest birds will exert the strongest stabilizing influence on highly profitable...
We evaluated performance (accuracy and efficiency) of the line-intersect and strip-plot methods for estimating the density, length, percent cover, and weight of logs important to wildlife. To conduct the evaluation, we sampled 17 coniferous stands in northeastern Oregon and northwestern Montana. These stands contained a gradient of log conditions b...
