Natural Resource Biometrics


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Natural Resource Biometrics

Mark and Recapture Methods

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Jolly-Seber Method: (Multiple marking)

Jolly-Seber method extend the mark and recapture method to open populations. The biggest change in the sampling procedures over the Schnabel method is the inclusion of the information of when a marked individual was last captured.

Advantages:

  1. Both Peterson and Schnabel assume closed populations, Jolly-Seber uses an open population (permits for birth, death, immigration, and emigration).

  2. The time interval between samples need not be constant, any number of samples (at least three!) can be accommodated so that series of data extending over many years can be used in the method.

Assumptions:

  1. Every individual has the same probability (a t) of being caught in the tth sample, whether it is marked or unmarked.

  2. Every marked individual has the same probability (f t) of surviving from the tth to the (t +1)st sample.

  3. Individuals do not lose their marks, and marks are not overlooked at capture.

  4. Sampling time is negligible in relation to the intervals between samples.

 

Alpha hat at timet is a estimate of the proportion  of the population that is marked.  Mt s an estimate of the marked population just before sample time t.   Nt is an estimate of the populations size at time t.

Table 1. After Krebs, 1989, page 38, Table 2.2

Mark-recapture Data for a series of 11 samples of a field vole

(Microtus pennsylvanicus) population in Southwestern Yukon

The dotted section represents the Z6 area and the gray section represents the R6 area.


Jolly-Seber Mark and Recapture Spreadsheet (Excel format)

Also See:

Chapter 2 - Estimating Abundance: Mark-and-Recapture pages 30-37 in:

Krebs, C. J. 1989. Ecological Methodology. Harper and Row, Publishers. New York. 654 pp.
Zar, J. H. 1996. Biostatistical Analysis. Prentice-Hall, Inc. Englewood Cliffs, New Jersey. 718 pp.
Created: August 17, 1998 by David R. Larsen
Last Updated: August 7, 2008