carcass (version 1.7)

ettersonEq14v2: Equation 14 of Etterson (2013) Ecological Applications 23, 1915-1925, adapted so that persistence probability and searcher efficiency can vary with age of the carcass

Description

Calculates the probability that a carcass that has fallen in the search area during n regular or irregular search intervals is found by a searcher.

Usage

ettersonEq14v2(s, f, J)

Value

the probability that a carcass that has fallen into the search area during the study is found by the searcher.

Arguments

s

vector of persistence probabilities with N elements, where N is the number of days in the full study period (i.e, N = sum(J)) (so N is the maximum number of days that a carcass could be present in the environment).

f

vector of discovery probabilities with n elements, where n is the number of searches performed.

J

a vector containing the lengths of the search intervals.

Author

M. A. Etterson

Details

This function assumes that persistence probability and searcher efficiency change over time and that this change depends upon the time elapsed since the carcass was killed (carcass age). If you assume that the change in detectability of a carcass is due to its age, then this function may not be reliable because it indexes the searcher efficiency to the number of searches the carcass has been exposed to. However, if you assume that searcher efficiency changes with the number of searches a carcass was exposed to because the easy carcasses are found first, then this function should perform well.

References

Etterson, M.A. (2013) Hidden Markov models for estimating animal mortality from antropogenic hazards. Ecological Applications, 23, 1915-1925.

See Also

ettersonEq14 ettersonEq14v1 pkorner phuso perickson

Examples

J <- c(2,3,2,4,3,5,3,2,3,4)
s <- plogis(seq(0.2, 2, length=sum(J)))
f <- plogis(seq(1.5, 0.9, length=length(J)))
ettersonEq14v2(s,f,J)