Discussion
This research compared area, shape, and locational accuracy of time- and
non-time-based home range estimators to assess the impacts of sample
size and GPS-point pattern shape. In general, GPS-point pattern shape
had more impact than sample size on results. BRB was the method that
maintained accuracy most consistently. The reasons for that are not
completely clear, however the localized variation of time and
reorientation with the advective coefficient might explain its overall
higher accuracy. BRB uses successive locations, rather than generating
global variables from an entire trajectory, which is the case in the
other time-based home range estimators, so BRB likely takes more
advantage of the spatiotemporal variability of telemetry data.
That sampling size greater than 125 points (the 05% sample size) had
less impact on accuracy than point pattern shape was consistent with
previous research comparing KDE and MCP (Downs and Horner 2008). The
comparison here also agrees with the findings of Downs and Horner
(2008), which found that KDE does not estimate home range area as
accurately as earlier studies suggest.
The findings for this research also correspond with Walter et al.
(2015), who found that time-based home range methods output home ranges
that more accurately fit GPS-point pattern shapes than point-based
methods. The research here extends the research by Walter et al. (2015)
and also found that time-based estimators are better at accurately
estimating area and location. However, KDE maintained location accuracy
reasonably well for different GPS-point pattern shapes, except for
perforated patterns.
It is worth noting that T-LoCoH offers the most input from a user
standpoint. Given the large number of tests ran for this research,
T-LoCoH was automated. During each simulation, the time was weighted at
a 60% level using the TSD metric, which is half way between the 40-80%
value that is recommended in method-1 of the T-LoCoH user guide (Lyons
2014). T-LoCoH estimates can vary depending on these inputs and further
tests of T-LoCoH would be warranted for future research. Yet, even with
automation, T-LoCoH still had a relatively high accuracy in estimating
home range area.