Estimating population trends with a linear model: Technical comments
John R. Sauer, William A. Link, J. Andrew Royle
2004, Condor (106) 435-440
Controversy has sometimes arisen over whether there is a need to accommodate the limitations of survey design in estimating population change from the count data collected in bird surveys. Analyses of surveys such as the North American Breeding Bird Survey (BBS) can be quite complex; it is natural to...
Reproduction in nondomestic birds: Physiology, semen collection, artificial insemination and cryopreservation
G.F. Gee, H. Bertschinger, A.M. Donoghue, J. Blanco, J. Soley
2004, Avian and Poultry Biology Reviews (15) 47-101
Pioneering work by Quinn and Burrows in the late 1930s led to successful artificial insemination (AI) programs in the domestic poultry industry. A variety of species specific modifications to the Quinn and Burrows massage technique made AI possible in nondomestic birds. Massage semen collection and insemination techniques span...
Estimating survival and breeding probability for pond-breeding amphibians: a modified robust design
L.L. Bailey, W. L. Kendall, D.R. Church, H.M. Wilbur
2004, Ecology (85) 2456-2466
Many studies of pond-breeding amphibians involve sampling individuals during migration to and from breeding habitats. Interpreting population processes and dynamics from these studies is difficult because (1) only a proportion of the population is observable each season, while an unknown proportion remains unobservable (e.g., non-breeding adults) and (2) not all...
Levels of fecal corticosterone in sandhill cranes during a human-led migration
B.K. Hartup, Glenn H. Olsen, Nancy M. Czekala, J. Paul-Murphy, J.A. Langenberg
2004, Journal of Wildlife Diseases (40) 267-272
Fourteen captive-reared greater sandhill cranes (Grus canadensis tabida) were conditioned to follow ultralight aircraft to promote migration between Wisconsin and Florida (USA) after release. Fecal samples were collected throughout the training period in Wisconsin and during a 1,977-km human-led migration to Florida to determine fecal corticosterone (FC) concentrations by radioimmunoassay....
Capture-recapture analysis for estimating manatee reproductive rates
W. L. Kendall, C.A. Langtimm, C.A. Beck, M.C. Runge
2004, Marine Mammal Science (20) 424-437
Modeling the life history of the endangered Florida manatee (Trichechus manatus latirostris) is an important step toward understanding its population dynamics and predicting its response to management actions. We developed a multi-state mark-resighting model for data collected under Pollock's robust design. This model estimates breeding probability conditional on a female's...
Sex ratio estimation and survival analysis for Orthetrum coerulescens (Odonata, Libellulidae)
M. Kery, L. Juillerat
2004, Canadian Journal of Zoology (82) 399-406
There is controversy over whether uneven sex ratios observed in mature dragonfly populations are a mere artifact resulting from the higher observability of males. Previous studies have at best made indirect inference about sex ratios by analysis of survival or recapture rates. Here, we obtain direct estimates of sex ratio...
The importance of environmental variability and management control error to optimal harvest policies
C.M. Hunter, M.C. Runge
2004, Journal of Wildlife Management (68) 585-594
State-dependent strategies (SDSs) are the most general form of harvest policy because they allow the harvest rate to depend, without constraint, on the state of the system. State-dependent strategies that provide an optimal harvest rate for any system state can be calculated, and stochasticity can be appropriately accommodated in this...
Estimation of tiger densities in the tropical dry forests of Panna, Central India, using photographic capture-recapture sampling
K.Ullas Karanth, Raghunandan S. Chundawat, James D. Nichols, N. Samba Kumar
2004, Animal Conservation (7) 285-290
Tropical dry-deciduous forests comprise more than 45% of the tiger (Panthera tigris) habitat in India. However, in the absence of rigorously derived estimates of ecological densities of tigers in dry forests, critical baseline data for managing tiger populations are lacking. In this study tiger densities were estimated using photographic capture–recapture...
A stage-based model of manatee population dynamics
M.C. Runge, C.A. Langtimm, W. L. Kendall
2004, Marine Mammal Science (20) 361-385
A stage-structured population model for the Florida manatee (Trichechus manatus latirostris) was developed that explicitly incorporates uncertainty in parameter estimates. The growth rates calculated with this model reflect the status of the regional populations over the most recent 10-yr period. The Northwest and Upper St. Johns River regions have growth...
Investigating species co-occurrence patterns when species are detected imperfectly
D.I. MacKenzie, L.L. Bailey, J.D. Nichols
2004, Journal of Animal Ecology (73) 546-555
1. Over the last 30 years there has been a great deal of interest in investigating patterns of species co-occurrence across a number of locations, which has led to the development of numerous methods to determine whether there is evidence that a particular pattern may not have occurred by random...
Native bees and plant pollination
H. S. Ginsberg
2004, Rhode Island Naturalist (11) 1-3
Bees are important pollinators, but evidence suggests that numbers of some species are declining. Decreases have been documented in the honey bee, Apis mellifera (which was introduced to North America), but there are no monitoring programs for the vast majority of native species, so we cannot be sure about...
Tigers and their prey: Predicting carnivore densities from prey abundance
K. U. Karanth, J.D. Nichols, S. Kumar, W.A. Link, J.E. Hines
2004, Proceedings of the National Academy of Sciences (101) 4854-4858
The goal of ecology is to understand interactions that determine the distribution and abundance of organisms. In principle, ecologists should be able to identify a small number of limiting resources for a species of interest, estimate densities of these resources at different locations across the landscape, and then use these...
Monitoring programs need to take into account imperfect species detectability
M. Kery, Hans Schmid
2004, Basic and Applied Ecology (5) 65-73
Biodiversiry monitoring is important to identify biological units in need of conservation and to check the effectiveness of conservation actions. Programs generally monitor species richness and its changes (trend). Usually, no correction is made for imperfect species detectability. Instead, it is assumed that each species present has...
Detecting warning signs of trouble within population fluctuations: using capture-recapture modeling to uncover changes in population dynamics leading to declines
J. A. Spendelow, J.D. Nichols, W. L. Kendall, J.E. Hines, Jeff S. Hatfield, I.C.T. Nisbet
2004, Annual Meeting of the Association of Field Ornithologists and the Wilson Ornithological Society Program and Abstracts P42
An intensive mark-recapture/resighting program has been carried out on the Roseate Terns nesting at Falkner Island, Connecticut, since the late 1980s as part of a regional study of the metapopulation dynamics and ecology of the endangered Northwest Atlantic breeding population of this species. Substantial losses of tern eggs and...
Sex Determination of Carolina Wrens (Thryothorus ludovicianus) in the Mississippi Alluvial Valley
D.J. Twedt
2004, North American Bird Bander (29) 171-174
I identified sexual dimorphism in wing length (unflattened chord) of Carolina Wrens (Thryothorus ludovicianus) within the central Mississippi Alluvial Valley (northeast Louisiana and west-central Mississippi) and used this difference to assign a sex to captured wrens. Wrens were identified as female when wing length was less than 57.5 mm...
N-mixture models for estimating population size from spatially replicated counts
J. Andrew Royle
2004, Biometrics (60) 108-115
Spatial replication is a common theme in count surveys of animals. Such surveys often generate sparse count data from which it is difficult to estimate population size while formally accounting for detection probability. In this article, I describe a class of models (n-mixture models) which allow for estimation of population...
Modeling abundance effects in distance sampling
J. Andrew Royle, D.K. Dawson, S. Bates
2004, Ecology (85) 1591-1597
Distance-sampling methods are commonly used in studies of animal populations to estimate population density. A common objective of such studies is to evaluate the relationship between abundance or density and covariates that describe animal habitat or other environmental influences. However, little attention has been focused on methods of modeling abundance...
Estimation of sex-specific survival from capture-recapture data when sex is not always known
J.D. Nichols, W. L. Kendall, J.E. Hines, J. A. Spendelow
2004, Ecology (85) 3192-3201
Many animals lack obvious sexual dimorphism, making assignment of sex difficult even for observed or captured animals. For many such species it is possible to assign sex with certainty only at some occasions; for example, when they exhibit certain types of behavior. A common approach to handling this situation in...
Generalized estimators of avian abundance from count survey data
J. Andrew Royle
2004, Animal Biodiversity and Conservation (27) 375-386
I consider modeling avian abundance from spatially referenced bird count data collected according to common protocols such as capture?recapture, multiple observer, removal sampling and simple point counts. Small sample sizes and large numbers of parameters have motivated many analyses that disregard the spatial indexing of the data, and thus...
Effectiveness of a confinement strategy for reducing campsite impacts in Shenandoah National Park
S. E. Reid, J. L. Marion
2004, Environmental Conservation (31) 274-282
The expansion and proliferation of backcountry campsites is a persistent problem in many parks and protected areas. Shenandoah National Park (SNP) has one of the highest backcountry overnight use densities in the USA national parks system. SNP managers implemented a multi-option backcountry camping policy in 2000 that included...
Individual heterogeneity and identifiability in capture-recapture models
W.A. Link
2004, Animal Biodiversity and Conservation (27) 87-91
Individual heterogeneity in detection probabilities is a far more serious problem for capture-recapture modeling than has previously been recognized. In this note, I illustrate that population size is not an identifiable parameter under the general closed population mark-recapture model Mh. The problem of identifiability is obvious if the population includes...
Computing and software
Gary C. White, J.E. Hines
2004, Animal Biodiversity and Conservation (27) 175-176
The reality is that the statistical methods used for analysis of data depend upon the availability of software. Analysis of marked animal data is no different than the rest of the statistical field. The methods used for analysis are those that are available in reliable software packages. Thus, the critical...
Evolution of quantitative methods for the study and management of avian populations: on the importance of individual contributions
J.D. Nichols
2004, Animal Biodiversity and Conservation (27) 3-19
The EURING meetings and the scientists who have attended them have contributed substantially to the growth of knowledge in the field of estimating parameters of animal populations. The contributions of David R. Anderson to process modeling, parameter estimation and decision analysis are briefly reviewed. Metrics are considered for assessing individual...
Costs of detection bias in index-based population monitoring
C. T. Moore, W. L. Kendall
2004, Animal Biodiversity and Conservation (27) 287-296
Managers of wildlife populations commonly rely on indirect, count-based measures of the population in making decisions regarding conservation, harvest, or control. The main appeal in the use of such counts is their low material expense compared to methods that directly measure the population. However, their correct use rests on...
Abundance estimation and conservation biology
J.D. Nichols, D.I. MacKenzie
2004, Animal Biodiversity and Conservation (27) 437-439
Abundance is the state variable of interest in most population–level ecological research and in most programs involving management and conservation of animal populations. Abundance is the single parameter of interest in capture–recapture models for closed populations (e.g., Darroch, 1958; Otis et al., 1978; Chao, 2001). The initial capture–recapture models developed...
