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Constraining movements in adehabitat

2 messages · Tim Clark, Pinaud David

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Dear List,

Sorry, this is a second attempt to post the same message.  My last one got scrubbed so I changed browser options.  Hopefully this one will make it!

I am using the package adehabitat to analyze the movement patterns and home range of the manta ray (Manta birostris) in Hawaii.  The manta rays in this study stayed close to shore, often feeding along the shore line or in small bays.  Since they can not go on land (being fish) their home range is obviously limited to the ocean area.  In calculating home range statistics, is there a way to limit the avalible area to the ocean.  I have read through the papers on Adehabitat but have not found a way to limit the area. The closest I have found is the function buffer().  Have I missed something?  Is there a way to constrain the movements so that kernels will only be computed for data points located in the ocean?

I appreciate your help and guidence.

Tim



Tim Clark
PhD Student 
University of Hawaii
Honolulu, HI 96816
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Dear Tim,

You can try several papers from Jason Matthioploulos, among:
Matthiopoulos (2003) The use of space by animals as a function of 
accessibility and
preference - Ecological Modelling 159 239-268
Matthiopoulos, J. 2003. Model-supervised kernel smoothing for the 
estimation of
spatial usage. ? Oikos 102: 367?377.
Unfortunately, I don't know a R implementation to do this directly. One 
(quick and dirty) way could be to weight the output of the Kernel 
estimation by a raster representing distance to coast (or ocean/continent)?

Hope it helps

David

Tim Clark a ?crit :