bottom_delim_halsey: Delimitate bottom phase of dive using wiggles and steps

In SESman/rbl: Biologging tools for diving predators in R

Description

Improves bottom_delim_std by defining a lower ledge (which implies longer bottoms) but reducing the bottom phase to a more relevant period (where specific behavior seems to indicate intensive foraging search). This is achieved by selecting the period between the first and last step/wiggle (see function wiggles) deeper than the ledge.

Usage

bottom_delim_halsey(time, depth = NULL, ledge = 0.5, vert_vel = 0.35)

Arguments

time	time readings, sorted in chronological order.
depth	depth readings, sorted in chronological order.
ledge	depth threshold, specified as a percentage which is compared to the maximum depth. 0.75 has been used for king pengins. For elephant seals: about 95 percent of prey catch attemps occur at depth greater than 50 percent of the maximum depth (default value 0.50).
vert_vel	A threshold used to define the steps. 0.35 m/s has been used for king pengins.

References

Halsey, L.G., Bost, C.-A. & Handrich, Y. (2007) A thorough and quantified method for classifying seabird diving behaviour. Polar Biology, 30, 991-1004.

See Also

wiggles

Examples

data(exses)
ind(exses)

n <- 65
idx <- tdrply(bottom_delim_halsey, 1:2, "!_/", no = n)[[1]]
tdrply(plot, 1:2, "!_/", no = n, main = n)
tdrply(function(x, st, ed, ...) points(x[st:ed, ]), 1:2, no = n, la = idx)

SESman/rbl documentation built on May 9, 2019, 11:10 a.m.