Abstract
Change-in-ratio (CIR) methods can provide an effective, low cost approach for estimating the size of wildlife populations. They rely on being able to observe changes in proportions of population subclasses that result from the removal of a known number of individuals from the population. These methods were first introduced in the 1940’s to estimate the size of populations with 2 subclasses under the assumption of equal subclass encounter probabilities. Over the next 40 years, closed population CIR models were developed to consider additional subclasses and use additional sampling periods. Models with assumptions about how encounter probabilities vary over time, rather than between subclasses, also received some attention. Recently, all of these CIR models have been shown to be special cases of a more general model. Under the general model, information from additional samples can be used to test assumptions about the encounter probabilities and to provide estimates of subclass sizes under relaxations of these assumptions. These developments have greatly extended the applicability of the methods. CIR methods are attractive because they do not require the marking of individuals, and subclass proportions often can be estimated with relatively simple sampling procedures. However, CIR methods require a carefully monitored removal of individuals from the population, and the estimates will be of poor quality unless the removals induce substantial changes in subclass proportions. In this paper, we review the state of the art for closed population estimation with CIR methods. Our emphasis is on the assumptions of CIR methods and on identifying situations where these methods are likely to be effective. We also identify some important areas for future CIR research.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
Literature Cited
Bhat, U. N. 1972. Elements of applied stochastic processes. John Wiley and Sons, Inc., New York, New York, USA.
Chapman, D. G. 1984. The estimation of biological populations. Annals of Mathematical Statistics 25: 1–15.
Chapman, D. G. 1955. Population estimation based on change of composition caused by a selective removal. Biometrika 42: 279–290.
Chapman, D. G., and G. I. Murphy. 1965. Estimates of mortality and population from survey-removal records. Biometrics 21: 921–935.
Conner, M.C., R. A. Lancia, and K. H. Pollock. 1986. Precision of the change-in-ratio technique for deer population management Journal of Wildlife Management 50: 125–129.
Hanson, W. R. 1963. Calculation of productivity, survival and abundance of selected vertebrates from sex and age ratios. Wildlife Monographs 9: 1–60.
Heimbuch, D. G., and J. M. Hoenig. 1989. Change-in-ratio estimators for habitat usage and relative population size. Biometrics 45: 439–451.
Hoenig, J. M., P. Pepin, and W. D. Lawing. 1990. Estimating relative survival rate for two groups of larval fishes from field data: do older larvae survive better than young? Fishery Bulletin 88: 485–491.
Kelker, G. H. 1940. Estimating deer populations by a differential hunting loss in the sexes. Proceedings of the Utah Academy of Science, Arts and Letters 17: 65–69.
Lander, R. H. 1962. A method of estimating mortality rates from change in composition. Journal Fisheries Research Board of Canada 19: 159–168.
Otis, D. L. 1980. An extension of the change-in-ratio method. Biometrics 36: 141–147.
Otis, D. L., K. P. Burnham, G. C. White, and D. R. Anderson. 1978. Statistical inference for capture data on closed animal populations. Wildlife Monographs 62: 1–135.
Paloheimo, J. E., and D. Fraser. 1981. Estimation of harvest rate and vulnerability from age and sex data. Journal of Wildlife Management 45: 948–958.
Paulik, G. J., and Robson, D. S. 1969. Statistical calculations for change-in-ratio estimators of population parameters. Journal of Wildlife Management 33: 1–27.
Pollock, K. H., R. A. Lancia, M. C. Conner, and B. L. Wood. 1985. A new change-in-ratio procedure robust to unequal catchability of types of animal. Biometrics 41: 653–662.
Seber, G. A. F. 1982. The estimation of animal abundance and related parameters. Oxford University Press, New York, New York, USA.
Udevitz, M. S. 1989. Change-in-ratio methods for estimating the size of closed populations. Dissertation, North Carolina State University, Raleigh, North Carolina.
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1992 Elsevier Science Publishers Ltd
About this chapter
Cite this chapter
Udevitz, M.S., Pollock, K.H. (1992). Change-In-Ratio Methods for Estimating Population Size. In: McCullough, D.R., Barrett, R.H. (eds) Wildlife 2001: Populations. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-2868-1_9
Download citation
DOI: https://doi.org/10.1007/978-94-011-2868-1_9
Publisher Name: Springer, Dordrecht
Print ISBN: 978-1-85166-876-2
Online ISBN: 978-94-011-2868-1
eBook Packages: Springer Book Archive