Nondetection of a species at site does not imply that the is absent unless probability detection 1. We propose model and likelihood-based method for estimating occupancy rates when probabilities are <1. The provides flexible framework enabling covariate information to be included allowing missing observations. Via computer simulation, we found good estimates rates, generally unbiased moderate (>0.3). estimated two anuran 32 wetland sites in Maryland, USA, from data collected during 2000 as...

Few species are likely to be so evident that they will always detected when present. Failing allow for the possibility a target was present, but undetected, at site lead biased estimates of occupancy, colonization, and local extinction probabilities. These population vital rates often interest in long-term monitoring programs metapopulation studies. We present model enables direct estimation these parameters probability detecting is less than 1. The does not require any assumptions process...

We describe an approach for estimating occupancy rate or the proportion of area occupied when heterogeneity in detection probability exists as a result variation abundance organism under study. The key feature such problems, which we exploit, is that induces probability. Thus, can be modeled Moreover, this linkage between and allows one to exploit heterogeneous model estimate underlying distribution abundances. Therefore, our method estimation from repeated observations presence absence...

The tiger (Panthera tigris) is an endangered, large felid whose demographic status poorly known across its distributional range in Asia. Previously applied methods for estimating abundance, using total counts based on tracks, have proved unreliable. Lack of reliable data densities not only has constrained our ability to understand the ecological factors shaping communities large, solitary felids, but also undermined effective conservation these animals. In this paper, we describe use a field...

We consider capture-recapture studies where release and recapture data are available from each of a number strata on every capture occasion. Strata may, for example, be geographic locations or physiological states. Movement animals among occurs with unknown probabilities, estimation these transition probabilities is the objective. describe computer routine carrying out analysis under model that assumes Markovian transitions reducedparameter versions this model. also introduce models relax...

Statistical inference for capture–recapture studies of open animal populations typically relies on the assumption that all emigration from studied population is permanent. However, there are many instances in which this unlikely to be met. We define two general models process temporary emigration: completely random and Markovian. then consider effects these types Jolly–Seber estimators arising full-likelihood approach robust design data. Capture–recapture data Pollock's provide basis...

The presence of transient animals, common enough in natural populations, invalidates the estimation survival by traditional capture-recapture (CR) models designed for study residents only. Also, transit is interesting itself. We thus develop here a class CR to describe transients. In order assess merits this approach we examine bias estimators transients relation power different tests detecting also compare relative efficiency an ad hoc dealing with that leaves out first observation each...

Abstract Techniques for estimation of absolute abundance wildlife populations have received a lot attention in recent years. The statistical research has been focused on intensive small‐scale studies. Recently, however, biologists desired to study animals at very large scales monitoring purposes. Population indices are widely used these extensive programs because they inexpensive compared estimates abundance. A crucial underlying assumption is that the population index ( C ) directly...

The goal of ecology is to understand interactions that determine the distribution and abundance organisms. In principle, ecologists should be able identify a small number limiting resources for species interest, estimate densities these at different locations across landscape, then use estimates predict density focal locations. practice, however, development functional relationships between abundances their has proven extremely difficult, examples such predictive ability are very rare....

Summary Recently, interest in species distribution modelling has increased following the development of new methods for analysis presence‐only data and deployment these user‐friendly powerful computer programs. However, reliable inference from tools requires that several assumptions be met, including observed presences are consequence random or representative sampling detectability during does not vary with covariates determine occurrence probability. Based on our interactions researchers...

Estimating species richness (i.e., the actual number of present in a given area) is basic objective many field studies carried out community ecology and also crucial concern when dealing with conservation management biodiversity. In most studies, total recorded an area at time taken as measure richness. Here we use capture–recapture approach to estimation North American Breeding Bird Survey (BBS) data order estimate detectability thus gain insight about its importance. particular, competing...

Population ecologists have devoted disproportionate attention to the esti— mation and study of birth death rates far less effort movement. Movement fidelity wintering areas important ecological evolutionary implications for avian populations. Previous inferences about movement among been restricted by limitations data methodology. We use multiple observation from a large—scale capture—resighting Canada Geese in Atlantic flyway estimate probabilities returning previous locations moving new...

Although point counts are frequently used in ornithological studies, basic assumptions about detection probabilities often untested. We apply a double-observer approach developed to estimate for aerial surveys (Cook and Jacobson 1979) avian counts. At each count, designated "primary" observer indicates another ("secondary") all birds detected. The secondary records detections of the primary as well any not detected by observer. Observers alternate roles during course survey. permits...

Journal Article Capture-Recapture Models: Using marked animals to study population dynamics Get access James D. Nichols Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 42, Issue 2, February 1992, Pages 94–102, https://doi.org/10.2307/1311650 Published: 01 1992

For the vast majority of cases, it is highly unlikely that all individuals a population will be encountered during study. Furthermore, constant fraction over times, locations, or species to compared. Hence, simple counts usually not good indices size. We recommend detection probabilities (the probability including an individual in count) estimated and incorporated into inference procedures. However, most techniques for estimating require moderate sample sizes, which may achievable when...

Summary Over the last 30 years there has been a great deal of interest in investigating patterns species co‐occurrence across number locations, which led to development numerous methods determine whether is evidence that particular pattern may not have occurred by random chance. A key aspect seems largely overlooked possibility always be detected at location when present, leads ‘false absences’ presence/absence matrix cause incorrect inferences made about patterns. Furthermore, many...