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David R. Anderson

Publications and source records attributed to David R. Anderson.

At least 37 records · Page 2Linked to original sources
USGS1984

Estimating the effect of hunting on annual survival rates of adult mallards

Management programs for waterfowl populations include rationale for, and establishment of, hunting regulations. These programs rest partially on the results of scientific studies on the effect of harvest rates on annual survival rates. The evidence of this relationship has changed markedly since the mid-1970's, and it is not widely believed that a largely compensatory relationship exists between hunting mortality and other forms of mortality for the mallard ( Anas platyrhynchos ). This paper employs a general probabilistic model formulated to include a parameter (b) representing a continuum between complete compensation (b=0) and total additivity (b=1). Maximum likelihood estimates of this parameter were computer for 47 data sets of adult mallards banded throughout North American before hunting commenced. We found additional evidence of a highly compensatory mortality process for adult male mallards, while the evidence for adults female mallards remains inconclusive. Effective harvest, land acquisition, and land management programs depend upon additional information on the chronology and mechanisms underlying a compensatory mortality process.

Journal of Wildlife Management↗
USGS1983

Density estimation of small-mammal populations using a trapping web and distance sampling methods

Distance sampling methodology is adapted to enable animal density (number per unit of area) to be estimated from capture-recapture and removal data. A trapping web design provides the link between capture data and distance sampling theory. The estimator of density is D = M t+1 f(0) , where M t+1 is the number of individuals captured and f(0) is computed from the M t+1 distances from the web center to the traps in which those individuals were first captured. It is possible to check qualitatively the critical assumption on which the web design and the estimator are based. This is a conceptual paper outlining a new methodology, not a definitive investigation of the best specific way to implement this method. Several alternative sampling and analysis methods are possible within the general framework of distance sampling theory; a few alternatives are discussed and an example is given.

Ecology↗
USGS1982

Capture-recapture and removal methods for sampling closed populations

The problem of estimating animal abundance is common in wildlife management and environmental impact asessment. Capture-recapture and removal methods are often used to estimate population size. Statistical Inference From Capture Data On Closed Animal Populations, a monograph by Otis et al. (1978), provides a comprehensive synthesis of much of the wildlife and statistical literature on the methods, as well as some extensions of the general theory. In our primer, we focus on capture-recapture and removal methods for trapping studies in which a population is assumed to be closed and do not treat open-population models, such as the Jolly-Seber model, or catch-effort methods in any detail. The primer, written for students interested in population estimation, is intended for use with the more theoretical monograph.

Report↗
USGS1981

Bobwhite population responses to exploitation: two problems

Recently, Roseberry (1979) attempted to (1) clarify the theoretical basis for harvesting bobwhite ( Colinus virginianus ), (2) assess the impact of varying intensities of harvest on standing densities and long-term yields, and (3) define a harvest strategy appropriate for the bobwhite resource in Illinois. That paper, based on 24 years of field data, unfortunately contains 2 methodological or conceptual errors that are fundamental to the three objectives. Both errors are subtle, and as other have made the same or similar errors in analysis, we identify the problems in a way we hope will be taken constructively.

Journal of Wildlife Management↗
USGS1980

Effect of delayed reporting of band recoveries on survival estimates

Brownie et al. (U.S. Fish and Wildl. Serv., Resource Publ. 131, 1978) presented 14 models based on an array of explicit assumptions for the study of survival in avian populations. These methods are replacing the life table methods previously used to estimate survival rates (e.g., Burnham and Anderson, J. Wildl. Manage. , 43: 356-366, 1979). The new methods allow survival or recovery rates, or both, to be constant, time-specific, or time- and age-specific. In studies to estimate survival rates for birds the data are often from recoveries of birds shot or found dead during the hunting season and reported to the Bird Banding Laboratory by sportsmen, conservation agency employees, or the general public. This note examines the bias in estimating annual survival due to a proportion of the recoveries being incorrectly reported a year late. Specifically, a few recoveries each year of, for example, adult male American Widgeon ( Anas americana ) banded in California are reported as being recovered in year i + 1 when in fact they were actually recovered the previous year i. Delayed reporting might typically be caused by people finding a band in their health clothing in the fall of the year and, being embarrassed about their failure to report the band when it was taken, report it a year late not mentioning the actual year of recovery. Heuristically, delayed reporting should bias estimated annual survival rates upwards because it appears from the data that the birds corresponding to the "delayed" recoveries actually lived an additional year.

Journal of Field Ornithology↗
USGS1980

The effect of band loss on estimates of annual survival

Banding has proven to be a useful technique in the study of population dynamics of avian species. However, band loss has long been recognized as a potential problem, (Hickey, 1952; Ludwig, 1967). Recently, Brownie et al. (1978) presented 14 models based on an array of explicit assumptions for the analysis of band recovery data. Various estimation models (assumption sets) allowed survival and/or recovery rates to be (a) constant, (b) time-specific, or (c) time- and age-specific. Optimal inference methods were employed and statistical tests of critical assumptions were developed and emphasized. The methods of Brownie et al. (1978), as with all previously published methods of which we are aware, assume no loss of bands during the study. However, some band loss is certain to occur and this potentially biases the estimates of annual survival rates whatever the analysis method. A few empirical studies have estimated band loss rates (a notable exception is Ludwig, 1967); consequently, for almost all band recovery data, the exact rate of band loss is unknown. In this paper we investigate the bias in estimates of annual survival rates due to varying degrees of hypothesized band loss. Our main results are based on perhaps the most useful model, originally developed by Seber (1970), for estimation of annual survival rate. Inferences are made concerning the bias of estimated survival rates in other models because the structure of these estimators is similar.

Journal of Field Ornithology↗
USGS1979

The composite dynamic method as evidence for age-specific waterfowl mortality

For the past 25 years estimation of mortality rates for waterfowl has been based almost entirely on the composite dynamic life table. We examined the specific assumptions for this method and derived a valid goodness of fit test. We performed this test on 45 data sets representing a cross section of banded sampled for various waterfowl species, geographic areas, banding periods, and age/sex classes. We found that: (1) the composite dynamic method was rejected (P <0.001) in 37 of the 45 data sets (in fact, 29 were rejected at P <0.00001) and (2) recovery and harvest rates are year-specific (a critical violation of the necessary assumptions). We conclude that the restrictive assumptions required for the composite dynamic method to produce valid estimates of mortality rates are not met in waterfowl data. Also we demonstrate that even when the required assumptions are met, the method produces very biased estimates of age-specific mortality rates. We believe the composite dynamic method should not be used in the analysis of waterfowl banding data. Furthermore, the composite dynamic method does not provide valid evidence for age-specific mortality rates in waterfowl.

Journal of Wildlife Management↗
USGS1979

Robust estimation from line transect data

Line transect sampling often provides a practical way to approach estimation of wildlife population density (Seber 1973, Eberhardt 1978). Burnham and Anderson (1976) provided a general framework for the estimation of animal density from line transect data, and many specific analytical methods have been proposed in the literature. Numerous persons are researching methods of statistical analysis for line transect data; however, little consideration has been given to specifying criteria for "good" methods of line transect estimation. We present here some criteria which we believe line transect estimators should satisfy. We do not deal with the case where objects may move from their initial location before being detected.

Journal of Wildlife Management↗
USGS1978

A log-linear model approach to estimation of population size using the line-transect sampling method

The technique of estimating wildlife population size and density using the belt or line-transect sampling method has been used in many past projects, such as the estimation of density of waterfowl nestling sites in marshes, and is being used currently in such areas as the assessment of Pacific porpoise stocks in regions of tuna fishing activity. A mathematical framework for line-transect methodology has only emerged in the last 5 yr. In the present article, we extend this mathematical framework to a line-transect estimator based upon a log-linear model approach.

Ecology↗