aniso: Spatially Explicit Capture-Recapture in Transformed Space

In MurrayEfford/secrBVN: Bivariate Normal Home Range SECR

Spatially Explicit Capture–Recapture in Transformed Space

Description

Fits SECR model using distances calculated in a space transformed by compression along a single axis. Both the orientation of the axis (ψ_A) and the compression ratio (ψ_R) are treated as parameters to be estimated. The general method was first applied by Murphy et al. (2016).

Usage

anisotropic.fit(..., psiA = pi/4, psiR = 2)

predictAniso(fit, angle = c("degrees", "radians"))

Arguments

...	arguments passed to ]secr.fit
psiA	numeric initial value of phiA
psiR	numeric initial value of phiR
fit	fitted model from anisotropic.fit
angle	units for angle

Details

The compression ratio ψ_R takes values greater than or equal to 1.0. The corresponding coefficient on the link scale is log(ψ_R - 1).

The function predictAniso extracts estimates of the transformation parameters from a fitted model and back-transforms psiR.

The estimate of the spatial scale parameter sigma applies in the isotropic compressed space; it may be understood as an estimate along the minor axis of each ellipse.

Value

For anisotropic.fit, a fitted secr model.

For predictAniso, a dataframe of two rows (psiA, psiR).

References

Murphy, S. M., Cox, J. J., Augustine, B. C., Hast, J. T., Guthrie, J. M., Wright, J., McDermott, J., Maehr, S. C. and Plaxico, J. H. (2016) Characterizing recolonization by a reintroduced bear population using genetic spatial capture–recapture. Journal of Wildlife Management 80, 1390–1407.

See Also

secr.fit

Examples

## view the function used internally for distances
secrBVN:::anisodistfn

## simulate data
tr <- make.grid(10, 10, spacing = 25, hollow = TRUE, detector = 'proximity')
pop <- simpopn.bvn(s2xy = (25*c(0.5,2))^2, theta = pi/4, core = tr, buffer = 200, 
                   D = 4, Ndist = 'fixed')
CH <- simcapt.bvn(tr, pop, type = 'BVN', lambda = 0.4, noccasions = 5)

## fit model
fit <- anisotropic.fit(CH, buffer = 200, detectfn = 'HHN', trace = FALSE)

## examine results
coef(fit)
predictAniso(fit)
predict(fit)

MurrayEfford/secrBVN documentation built on Oct. 14, 2022, 5:20 a.m.