John Sauer, Ph.D.
John Sauer is a Wildlife Biologist at the Eastern Ecological Science Center in Laurel, MD.
He has also worked as a Statistician with the U. S. Fish and Wildlife Service and as a Lecturer at the University of Kansas. John is an Elective Fellow of the American Ornithological Society and serves on the Board of Editors of Ecology, Ecological Monographs, and Avian Conservation and Ecology. John has been awarded the AOS Ralph W. Schreiber Conservation Award (2018) and a United States Department of Interior Distinguished Service Award (2018).
John participates in a wide variety of research projects united by the general themes of population ecology, survey design and analysis, geographic and temporal analysis of population change, analysis of count data, geographical ecology, and summary and display of large-scale surveys. Current projects include:
Analysis of population change from count data-John has participated in a series of research projects associated with analysis of population change from count data. Along with a variety of collaborators, he develops methods for analysis of counts in which counts are modeled hierarchically, as over-dispersed Poisson random variables, allowing for adjustment of both factors that influence visibility of animals and factors that actually influence population sizes. These methods are presently being implemented for the North American Breeding Bird Survey, the Christmas Bird Count, breeding waterfowl surveys in the Northeastern United States and Canada, and the Woodcock Singing-ground Survey. The methods are also used for spatial modeling and landscape level analyses, addressing questions relevant to conservation and ecology. He conducts yearly analyses of all North American Breeding Bird Survey data, and consults with researchers and managers who use the database.
Development of internet-based procedures for summary and analysis of survey data-In collaboration with other Patuxent staff, John has developed a series of web sites that allow users access to information from the North American Breeding Bird Survey and other datasets. Survey data can be accessed at several geographic scales, from individual sample units to continental summaries. A recent innovation is development of a map-based application that integrates BBS and displays BBS results at multiple geographic scale, similar to USGS mapping products associated with water resources. Custom analyses of population change can be conducted for regions, species, and time periods specified by users. Website address: http://www.mbr-pwrc.usgs.gov
Evaluating the Design of the Waterfowl Breeding Population and Habitat Survey-The Waterfowl Breeding Population and Habitat Survey (WBPHS) is a primary source of waterfowl population status and trend information for management of ducks in North America. John, along with colleagues in the United States Fish and Wildlife Service, are reviewing the current distributions of priority waterfowl species relative to the scope of the WBPHS, suggestin
Science and Products
Science for avian conservation: Priorities for the new millennium
Hierarchical models and the analysis of bird survey information
Statistical mapping of count survey data
Disentangling sampling and ecological explanations underlying species-area relationships
On the estimation of species richness based on the accumulation of previously unrecorded species
A removal model for estimating detection probabilities from point-count surveys
An evaluation of population index and estimation techniques for tadpoles in desert pools
A hierarchical analysis of population change with application to Cerulean Warblers
Large scale wildlife monitoring studies: Statistical methods for design and analysis
Book review: Bird census techniques, Second edition
Using Christmas Bird Count data in analysis of population change
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Science for avian conservation: Priorities for the new millennium
Over the past decade, bird conservation activities have become the preeminent natural resource conservation effort in North America. Maturation of the North American Waterfowl Management Plan (NAWMP), establishment of Partners in Flight (PIF), and creation of comprehensive colonial waterbird and shorebird conservation plans have stimulated unprecedented interest in, and funding for, bird conservatAuthorsJ. M. Ruth, D. R. Petit, J.R. Sauer, M. D. Samuel, F.A. Johnson, M.D. Fornwall, C. E. Korschgen, J. P. BennettHierarchical models and the analysis of bird survey information
Management of birds often requires analysis of collections of estimates. We describe a hierarchical modeling approach to the analysis of these data, in which parameters associated with the individual species estimates are treated as random variables, and probability statements are made about the species parameters conditioned on the data. A Markov-Chain Monte Carlo (MCMC) procedure is used to fiAuthorsJ.R. Sauer, W. A. LinkStatistical mapping of count survey data
We apply a Poisson mixed model to the problem of mapping (or predicting) bird relative abundance from counts collected from the North American Breeding Bird Survey (BBS). The model expresses the logarithm of the Poisson mean as a sum of a fixed term (which may depend on habitat variables) and a random effect which accounts for remaining unexplained variation. The random effect is assumed to be sAuthorsJ. Andrew Royle, W. A. Link, J.R. SauerDisentangling sampling and ecological explanations underlying species-area relationships
We used a probabilistic approach to address the influence of sampling artifacts on the form of species-area relationships (SARs). We developed a model in which the increase in observed species richness is a function of sampling effort exclusively. We assumed that effort depends on area sampled, and we generated species-area curves under that model. These curves can be realistic looking. We thenAuthorsE. Cam, J. D. Nichols, J. E. Hines, J.R. Sauer, R. Alpizar-Jara, C.H. FlatherOn the estimation of species richness based on the accumulation of previously unrecorded species
Estimation of species richness of local communities has become an important topic in community ecology and monitoring. Investigators can seldom enumerate all the species present in the area of interest during sampling sessions. If the location of interest is sampled repeatedly within a short time period, the number of new species recorded is typically largest in the initial sample and decreasesAuthorsE. Cam, J. D. Nichols, J.R. Sauer, J. E. HinesA removal model for estimating detection probabilities from point-count surveys
Use of point-count surveys is a popular method for collecting data on abundance and distribution of birds. However, analyses of such data often ignore potential differences in detection probability. We adapted a removal model to directly estimate detection probability during point-count surveys. The model assumes that singing frequency is a major factor influencing probability of detection when biAuthorsG.L. Farnsworth, K. H. Pollock, J. D. Nichols, T.R. Simons, J. E. Hines, J.R. SauerAn evaluation of population index and estimation techniques for tadpoles in desert pools
Using visual (VI) and dip net indices (DI) and double-observer (DOE), removal (RE), and neutral red dye capture-recapture (CRE) estimates, we counted, estimated, and censused Couch's spadefoot (Scaphiopus couchii) and canyon treefrog (Hyla arenicolor) tadpole populations in Big Bend National Park, Texas. Initial dye experiments helped us determine appropriate dye concentrations and exposure timesAuthorsRobin E. Jung, Gage H. Dayton, Stephen J. Williamson, John R. Sauer, Sam DroegeA hierarchical analysis of population change with application to Cerulean Warblers
Estimation of population change from count surveys is complicated by variation in quality of information among sample units, by the need for covariates to accommodate factors that influence detectability of animals, and by multiple geographic scales of interest. We present a hierarchical model for estimation of population change from the North American Breeding Bird Survey. Hierarchical models, inAuthorsW. A. Link, J.R. SauerLarge scale wildlife monitoring studies: Statistical methods for design and analysis
Techniques for estimation of absolute abundance of wildlife populations have received a lot of attention in recent years. The statistical research has been focused on intensive small-scale studies. Recently, however, wildlife biologists have desired to study populations of animals at very large scales for monitoring purposes. Population indices are widely used in these extensive monitoring programAuthorsK. H. Pollock, J. D. Nichols, T.R. Simons, G.L. Farnsworth, L.L. Bailey, J.R. SauerBook review: Bird census techniques, Second edition
Conservation concerns, federal mandates to monitor birds, and citizen science programs have spawned a variety of surveys that collect information on bird populations. Unfortunately, all too frequently these surveys are poorly designed and use inappropriate counting methods. Some of the flawed approaches reflect a lack of understanding of statistical design; many ornithologists simply are not awareAuthorsJohn R. SauerUsing Christmas Bird Count data in analysis of population change
The scientific credibility of Christmas Bird Count (CBC) results depend on the development and implementation of appropriate methods of statistical analysis. The key to any successful analysis of CBC data is to begin with a careful review of how the limitations of the data are likely to influence the results of the analysis, then to choose methods of analysis that accommodate as much as possibleAuthorsJ.R. Sauer, W. A. Link - Web Tools