Description Usage Arguments Details Value References Examples
Estimates animal density (amongst other parameters) from two-plane
aerial surveys. This conceptualises sighting locations as a
Neyman-Scott point pattern—estimation is carried out via
fit.ns()
.
1 2 |
points |
A vector (or single-column matrix) containing the distance along the transect that each detection was made. |
planes |
An optional vector containing the plane ID (either
|
d |
The length of the transect flown (in km). |
w |
The distance from the transect to which detection of individuals on the surface is certain. This is equivalent to the half-width of the detection zone. |
b |
The distance from the transect to the edge of the area of interest. Conceptually, the distance between the transect and the furthest distance a whale could be on the passing on the first plane and plausibly move into the detection zone by the passing of the second plane. |
l |
The lag between planes (in seconds). |
tau |
Mean dive-cycle duration (in seconds). |
R |
Truncation distance (see fit.ns). |
edge.correction |
The method used for the correction of edge
effects. Either |
start |
A named vector of starting values for the model parameters. |
bounds |
A list with named components. Each component should be a vector of length two, giving the upper and lower bounds for the named parameter. |
trace |
Logical, if |
This function is simply a wrapper for fit.ns
, and
facilitates the fitting of the model proposed by Stevenson,
Borchers, and Fewster (in prep). This function presents the
parameter D.2D
(two-dimensional cetacean density in
cetaceans per square km) rather than D
for enhanced
interpretability.
An R6 reference class object. Extraction of the information held within is best handled by functions coef.nspp, confint.nspp, summary.nspp, and plot.nspp.
Stevenson, B. C., Borchers, D. L., and Fewster, R. M. (in prep) Trace-contrast methods to account for identification uncertainty on aerial surveys of cetacean populations.
1 2 | fit <- fit.twoplane(points = example.twoplane$points, planes = example.twoplane$planes,
d = 500, w = 0.175, b = 0.5, l = 20, tau = 110, R = 1)
|
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