eisera {adehabitat} | R Documentation

## Eigenanalysis of Selection Ratios

### Description

Performs an eigenanalysis of selection ratios.

### Usage

    eisera(used, available, scannf = TRUE, nf = 2)
    print.esr(x, ...)
    scatter.esr(x, xax = 1, yax = 2,
                csub = 1, possub = "bottomleft", ...)

### Arguments

`used` | a data frame containing the *number* of relocations of each animal (rows) in each habitat type (columns)
`available` | a data frame containing the *proportion* of availability of each habitat type (columns) to each animal (rows)
`scannf` | logical. Whether the eigenvalues bar plot should be displayed
`nf` | if `scannf = FALSE`, an integer indicating the number of kept axes
`x` | an object of class `esr`
`xax` | the column number for the x-axis
`yax` | the column number for the y-axis
`csub` | a character size for the legend, used with `par("cex")*csub`
`possub` | a string of characters indicating the sub-title position ("topleft", "topright", "bottomleft", "bottomright")
`...` | further arguments passed to or from other methods

### Details

The eigenanalysis of selection ratios has been developped to explore habitat selection by animals monitored using radio-tracking, when habitat is defined by several categories (e.g. several vegetation types, see Calenge and Dufour 2006).

This analysis can be used for both designs II (same availability for all animals, e.g. selection of the home range within the study area) and designs III (different availability, e.g. selection of the sites within the home range). In the latter case, when some available proportions are equal to zero, the selection ratios are replaced by their expectation under random habitat use, following the recommendations of Calenge and Dufour (2006).

### Value

An object of class `esr`

### Author(s)

Clément Calenge calenge@biomserv.univ-lyon1.fr

### References

Calenge, C. and Dufour, A.B. (2006) Eigenanalysis of selection ratios from animal radio-tracking data. Ecology. in press.

### See Also

`widesII` for further information about the selection ratios, `compana` for compositional analysis.

### Examples

    ###########################################################
    ###########################################################
    ###
    ###  Example given in Calenge and Dufour 2006 (design II)

    data(squirrel)

    ## computation of the number of relocations in each habitat type
    ## from the data given by Aebischer et al. (1993).
    ## squirrel$locs give the percentage of relocations in each habitat
    ## type, and Aebischer et al. (1993) indicate that there are 30
    ## relocations per animal.
    ## We therefore compute the number of relocations in each habitat type
    ## using:
    us <- round(30 * squirrel$locs / 100)

    ## Habitat availability
    av <- squirrel$studyarea

    ## Eigenanalysis of selection ratios
    ii <- eisera(us, av, scannf = FALSE)

    scatter(ii, grid = FALSE, clab = 0.7)

    ###########################################################
    ###########################################################
    ###
    ###  Example of design III

    iii <- eisera(us, squirrel$mcp, scannf = FALSE)
    scatter(iii, grid = FALSE, clab = 0.7)

[Package adehabitat version 1.4 Index]