Geography Reference
In-Depth Information
citizens over a duration of one day per respondent, while the possum data tracked a
limited number of individuals, but over a period of more than one year. (2)
Possums are nocturnal and they also respond to seasonal cycles while humans are
more adapted to 24 h, 7 day cycles. (3) Spatial context is different, e.g., home for
humans is relatively permanent and static, while possums' dens are generally
semi-permanent and philopatric. There are many convenient spatial areas for
associating human movement and activities, e.g., census tracts, while for possums
these are much fewer. All these differences should be considered when modifying
ringmaps to explore the movements of possums.
Figure
6
depicts a modified ringmap for a single possum (#6012), showing the
same information as in Fig.
5
a and b, but in a compact and cyclic manner where
nightly cycles are shown and space and time are visualised explicitly.
Unlike the 2-D ringmaps made for Halifax data, where only one group of rings
shows one variable over a 24-hour cycle (Zhao et al.
2008
), the ringmap in Fig.
6
is altered to use two groups of rings to represent two variables, habitat and
behaviour, with a nightly cycle over equivalent time periods, 8 nights. Each ring
represents patterns of habitat use or behaviour over a night, and each group of
rings is ordered similarly. In this case the rings are ordered by date to allow
comparison between variables. Sectors represent the time after sunset, ordered
clockwise along an arc axis over 5-min intervals. If needed, additional groups of
rings can be added to display more variables in order to reveal other relationships
among movement behaviour and its motivating factors. The ordering of groups of
rings also can be changed to reflect a different variable. Given the fine grain GPS
tracking data and the limited number of possums tracked, it is possible to show
information at an individual level, unlike aggregated ringmaps for Halifax data.
The inset photo map is used only as a background to indicate relevant environ-
mental information. However, the inset possum timelines and the ringmaps of
behaviour and habitat are interactively linked to each other. For example, if one
selects movement paths for night 1 from the timelines, the two ringmaps will be
able to highlight corresponding behaviour and habitat sectors for night 1.
One of the strengths of ringmaps is their ability to illustrate cycles. The types of
cycles that can be mapped are flexible, dependent on the nature of data. In the
examples, the movement patterns of possums are heavily influenced by season and
habitat, and tracking data are available for more than 1 year, so we assessed a
seasonal ringmap of habitat use at an individual scale where each sector repre-
sented a night in the year (ordered clockwise), while rings displayed time after
sunset, projected outwards from the centre with each ring represented a 10-min
interval (Fig.
7
).
The ringmap in Fig.
7
depicts nightly patterns of habitat use of a single male
possum (#1882) expressed over a year, beginning in March 2007. The timelines at
multiple temporal scales are processed/interpolated into 10-min intervals. In the
example, at the seasonal scale, the possum shifted during the New Zealand spring
(September to November) and early summer (December) from extensive use of
patches of manuka/kanuka (Leptospermum spp.) bushlands, to increased use of dry
and wet native forest during the late summer (February), to heightened use of
