Capture-Mark-Recapture Science

Science Center Objects

Capture-Mark-Recapture (CMR) can be viewed as an animal survey method in which the count statistic is the total number of animals caught, and the associated detection probability is the probability of capture.  The method involves capturing a number of animals, marking them, releasing them back into the population, and then determining the ratio of marked to unmarked animals in the population.

Camera Trap photo of a Tiger

Camera Trap photo of a Tiger (Public domain.)

Development of Methods Associated with Animal Population Dynamics

Conservation and management of natural animal populations requires knowledge of their dynamics and associated environmental and management influences. Specifically, informed management requires periodic estimates of system state (e.g., population size) and models for projecting consequences of management actions for subsequent state dynamics. However, it is very difficult to draw strong inferences about system state and dynamics for natural animal populations and communities. The primary challenges are: (1) the tendency of animal densities to vary substantially over space and (2) the likelihood that any method of sampling animals (capture, direct observation, etc.) will produce counts that represent some unknown fraction of the true number of animals in the sampled locations.


Scrub Jay

Patch Occupancy Models a conservation applications that can focus on endangered species management for the conservation of Florida scrub jays. (Public domain.)



Development of Patch Occupancy Models for Assessing the Spatial Distribution of Organisms

A variety of important questions about the conservation and management of natural resources requires information about the spatial distribution of organisms. For species of conservation concern, the size of a species’ range is a criterion used to assign species status as threatened or endangered. For invasive species and disease organisms, the dynamics of the species range expansion are relevant to efforts to both control invasions and to protect vulnerable species. In this period of rapid global change, it will be important to be able to understand and predict dynamics of species ranges as habitats change in suitability.




American Toad Calling

American Toad Calling (Public domain.)



Statistical Research for the USGS - Amphibian Research and Monitoring Initiative

Since its inception in 2002 the USGS Amphibian Research and Monitoring Initiative (ARMI) has taken the lead in monitoring amphibian populations on Department of Interior lands. ARMI scientists work on a broad spectrum of species and management issues to address the core causes of amphibian declines. In many cases, research requires complex study designs and innovative methods. A key program need for ARMI has been to develop a robust set of quantitative methods for estimating patterns and dynamics of species presence.




Aluminum band and one plastic colored leg bands in a Brown Pelican 

Aluminum band and one plastic colored leg bands in a Brown Pelican. (Courtesy: Holly E. Cox)





Bird Banding Laboratory

The Bird Banding Laboratory (BBL) is an integrated scientific program supporting the collection, archiving, management and dissemination of information from banded and marked birds in North America to monitor the status and trends of resident and migratory bird populations. As birds are good indicators of the health of the environment, the status and trends of bird populations are critical for identifying and understanding many ecological issues and for developing effective science, management and conservation practices.





Key Largo woodrat (Neotoma floridana smalli - KLWR)

Key Largo woodrat (Neotoma floridana smalli - KLWR) (Public domain.)





Assessing Endangered Marsh Rabbit and Woodrat Habitat use and Predator Population Dynamics

Feral and free-ranging domestic cats (Felis catus) have strong negative effects on wildlife, particularly in island ecosystems such as the Florida Keys. We deployed camera traps to study free-ranging cats in National Wildlife Refuges and state parks on Big Pine Key and Key Largo and used spatial models to estimate cat population dynamics and stable isotope analyses to examine cat diets. Top models separated cats based on movements and activity patterns and represent feral, semi-feral, and indoor/outdoor house cats. We provide evidence that cat groups within a population move different distances, exhibit different activity patterns, and that individuals consume wildlife at different rates - all of which have implications for managing this invasive predator.

Banding Hen Eider

Banding a Hen Eider  (Public domain.)






Survival and Recruitment of Common Eiders in the Gulf of Maine

Common eider numbers are declining throughout most of their range. The cause of this decline is not known, but poor recruitment, declining food resources, hunting, poor survival are possible causes. Research goals of this project focus on understanding the effects of hunting and predation on survival and recruitment rates of American common eiders (Somateria mollissima) in the Atlantic coast population, especially Maine. The project uses traditional band analysis methodologies as well as mark -recapture methods. Select islands and archipelagos in the Gulf of Maine constitute the study area. Eiders are captured by hand nets and in drive traps and banded with standard USGS bands. Over the last 10 years, we have returned to the same islands to band unmarked birds and record bands of previously banded birds. Analyses are ongoing to determine survival, recruitment, and recovery rates of Eiders in Maine. The ultimate goal is to provide information that can be included in specific management models for declining migratory bird populations.



Spatial Capture-Recapture by Royle,Chandler, Sollmann, & Gardner

 Royle, J. A., Chandler, R. B., Sollmann, R., and Gardner, B., 2014, Spatial capture-recapture: Amsterdam,  Elsevier.    xxix, 577  p. (Public domain.)





Spatial Capture-Recapture Models to Estimate Abundance and Density of Animal Populations

For decades, capture-recapture methods have been the cornerstone of ecological statistics as applied to population biology.  While capture-recapture has become the standard sampling and analytical framework for the study of population processes (Williams, Nichols & Conroy 2002) it has advanced independent of and remained unconnected to the spatial structure of the population or the landscape within which populations exist. Furthermore, capture-recapture does not invoke any spatially explicit biological processes and thus is distinctly non-spatial, accounting neither for the inherent spatial nature of the sampling nor of the spatial distribution of individual encounters.  Linking observed encounter histories of individuals to mechanisms of spatial population ecology will enable ecologists to study these processes using new technologies such as noninvasive genetics, remote cameras and bioacoustic sampling.



USGS-PWRC population modeling software web-page

Programs that were developed at PWRC and elsewhere for the analysis of animal populations for wildlife biologists/managers. (Public domain.)






Development of Computer Software for the Analysis of Animal Population Parameters

Biologists at USGS Patuxent, as well as cooperating agencies are constantly looking for new ways of answering questions about the status of animal populations and how animal populations change over time. To address these questions, data are collected on captures and or sightings of animals which can be used to estimate parameters which affect the population using legacy software. Over time, new questions and methods for addressing these questions arise which require new computer software.




Elastomer marks on a Turquoise darter (Etheostoma inscriptum)

Elastomer marks on a Turquoise darter (Etheostoma inscriptum), used in mark-recapture to estimate fish survival in relation to streamflow variability. (Public domain.)



Quantifying Effects of Flow Variability on Riverine Biota

Ecologists have shown that many ecological processes in rivers, including organism growth, reproduction, survival and dispersal, are attuned to natural patterns of streamflow variability.  However, to predict how riverine biota will respond to flow alteration caused by, for example, water diversions and dam operations, ecologists need to understand the mechanisms through which changes in streamflow affect plant and animal populations.  Therefore, we are conducting field studies and analyses to test hypothesized effects of streamflow variability on population (survival, reproduction, extirpation, colonization) and trophic (primary production and consumption) dynamics.

Colorbanded Roseate Tern, Sterna dougallii

Color banded Roseate Terns that can be identified repeatedly at distances up to 50 meters or more are providing a wealth of new information about the movements, behavior, and population dynamics of this endangered species. (Public domain.)




Modeling Sex-specific Demographic Rates in Metapopulations

Research that integrates population dynamics and ecological studies is needed to identify the causal factors involved in population declines and viability. For highly mobile organisms such as birds, “between-patch” movements and the use of different geographic sites and habitats at various stages of the annual cycle can make it difficult to measure the effectiveness of “within-patch” site-specific management activities. These local restoration activities must be evaluated within the context of overall population changes on a regional or metapopulation scale. The major objective of this study is to develop new multistate capture-recapture/resighting and ultrastructural models to examine sex- and age- specific regional survival, movement, and recruitment rates. Once developed and tested with data collected from a long-term regional metapopulation study of a suitable species, these general types of models can be adapted for widespread use on a variety of other species.