getdetectpar: Ballpark Detection Parameters

Description

Detection parameters for an animal population may be guessed from some basic inputs (population density, a coefficent of home-range overlap, and the expected number of detections on a given detector array). These values are useful as a starting point for study design. They are not 'estimates'.

Usage

getdetectpar(D, C, sigma = NULL, k = 0.5, ...)

Arguments

population density animals / hectare; may be scalar or vector of length nrow(mask)

integer expected total number of detections

sigma

numeric spatial scale parameter of chosen detection function, in metres (optional)

coefficient of overlap - typically in range 0.3 to 1.1

…

named arguments passed to Enrm and Lambda (traps, mask, noccasions, detectfn)

Value

A list with one component for each detection parameter.

Details

If sigma is missing and detectfn = `HHN' then sigma is first inferred from the relationship \(\sigma = 100 k \sqrt D\) (\(D\) in animals per hectare and \(\sigma\) in metres). Other detectfn give an error.

A numerical search is then conducted for the value of lambda0 that results in C expected detections for the given density and design. The calculation takes account of the detector array, the habitat mask and the number of sampling occasions (all specified in the … argument - see example).

Only hazard detection functions are supported (`HHN', `HHR', `HEX', `HAN', `HCG'). The default is `HHN'.

Examples

Run this code

# NOT RUN {
tr <- traps(captdata)
detector(tr) <- "multi"
msk <- make.mask(tr, buffer = 100, type = 'trapbuffer')
getdetectpar(D = 5.48, C = 235, traps = tr, mask = msk, noccasions = 5)

# }