[tlocoh-info] Reporting home ranges (wet and dry seasons combined) and seasonal home ranges
lyons.andy at gmail.com
Wed Feb 25 17:41:59 CET 2015
Thanks for your query. See my comments below, and let us know if you
have any other questions.
On 2/23/2015 6:16 PM, elikana kalumanga wrote:
> Hi Tlocoh users,
> I have calculated the home ranges of six different animals using
> HR_area[]@data and got the results as shown below. a) Is it
> allowable to present results as I have done in Table 1?
I'm not sure what you mean 'allowable', but your table looks fine.
Isopleth area is given in map units squared, so if your map units are
meters then dividing by 10^6 gives you km2 (as you've done). A reader
may want to know more what 'duplicate points' means. because two fixes
at the same location are fine as long as they have different time stamps.
> b) Is it allowable to partition the lxy object into seasons (Wet and
> Dry) and calculate seasonal home ranges using the same k and s values?
> k=15, s=0.01
When you're working with subsets of your data from the same individual,
using the same parameter values (k and s) is pretty standard, and
certainly defensible in terms of comparing apples to apples. This
presumes that the movement pattern and sampling intervals in the wet and
dry seasons are not dramatically different. If on the other hand, for
example, there are many more spatial outliers in the dry season (because
the animal was wondering far and yonder in search of water sources),
then the same value of k that did a nice job modeling space use in the
wet season could potentially result in large ispoleths in the dry season
that include large areas where the animal never was (in which case you
might to switch to the 'a' method which is generally more robust to
different geometric distributions of points). Hence inspecting the
isopleth-area curves and isopleth maps for a reality check is still
worth doing, but if they are not too dissimilar then using the same
parameter values would be a good choice.
> Thanks you,
> A: Calculating the home ranges (50% core and 95% HR) for K
> iso.level area edge.len nep ptp hm.val num.hulls
> 1 0.10 70269838 108903.2 306 0.1039755 9151933 76
> 2 0.25 202560380 241182.6 751 0.2551818 13458959 161
> 3 0.50 411476203 396289.0 1478 0.5022086 17707306 296
> 4 0.75 795190800 498162.6 2223 0.7553517 25729873 578
> 5 0.95 1930117958 593033.8 2800 0.9514101 64256706 1873
> Table 1: Number of fixes and estimated home ranges from the lhs
> Number of fixes (GPS points)
> Duplicate points
> Number of days/dates
> Core area (km^2 )
> Home range
> 2012-08-15 2014-08-29
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