Appendix
In this section, we aim to elucidate on the technique used to estimate armadillo's
activity patterns through temperature monitoring and its associated costs. Figure 1
shows how the comparison between Tarmadillo, Tburrow and Tair patterns allows the
inference of activity status. In Figure 1a and 1c, it is possible to notice that the activity
pattern can be inferred from Tarmadillo variation pattern, even when data on Tburrow is
absent. In 2007 we placed temperature loggers only in the armadillos and obtained
records of air temperature hourly from the automatic meteorological station of the
Nhumirim ranch.
An activity simulation was also performed to assess whether our method was
reliable at inferring when the armadillos were active. Two temperature loggers were
placed inside a burrow (1 meter deep). After a given period, we removed one for several
hours and then placed it back inside the burrow. We repeated this procedure for several
days in three burrows and were able to create a pattern similar to our armadillo activity
dataset (Figure 1e).
Further details on data processing and analysis can also be found on Murray and
Smith (2012), who used a similar method to monitor desert woodrat activity patterns.
Fig. 1 Temperature records obtained from data-loggers in a 72-hour period in the
Brazilian Pantanal wetlands, during September 2007 and from February 2010 to May
2010. Armadillos' individual temperature records (Tarmadillo), obtained from data-loggers
fixed externally to two yellow armadillos (Euphractus sexcinctus; a and b), two ninebanded armadillos (Dasypus novemcinctus; c and d), and from an activity simulation (e)
are represented by dotted lines. Continuous lines represent temperature records obtained
from data-loggers placed inside burrows (Tburrow). Dashed lines represent air
temperature records obtained from an automatic meteorological station (Tair). Gray
bands highlight the periods when the animals were active, with Tarmadillo oscillating with
Tair.
Methodology costs and implications
Determining the activity period of mammals is challenging and all current
methodologies have restrictions. For example, both radio telemetry and direct
observation demand intensive, time-consuming effort. Although some transmitters are
equipped with motion sensitive devices that provide reliable information about activity,
such equipment often requires considerable human effort or an expensive data logging
receiver. In addition, researchers may cause disturbance when tracking an animal with a
transmitter, consequently biasing results. Our method allows intensive monitoring of
activity without any disturbance caused by 'homing in' techniques.
Each temperature logger costs US$159.00 (www.onsetcomp.com) and each
VHF transmitter costs US$173.00. As the expected battery life was far longer than our
short monitoring time (i.e. ≤18 days), we managed to reutilize transmitters and
temperature loggers in different armadillos. Thus, considering the expected battery life
of the transmitter (~950 days), if 3 temperature loggers are used (1 for the armadillo, 1
for the burrow and 1 for air temperature), we estimate the daily cost of our method at
US$0.68 per animal. If a meteorological station is available for the study area and only
one temperature logger is used (attached to the armadillo), the daily cost lowers to
US$0.35 per animal. The cost of permanent equipment was not included in these
calculations (receptor = US$737, antenna = US$141), as it was already available to us.
Hence, as shown in previous studies (e.g. Murray and Smith 2012), this method
has shown to be an effective, low-cost means of obtaining full-time monitoring of the
activity period of burrowing animals and could be added as a complement to radio
telemetry or GPS monitoring studies in order to supply a more complete set of data.