RESULTS
Twenty-four out of the 30 concrete shelters and 19 out of the 30 wooden
shelters were occupied at least once by A. robusta during the
field test period. Cameras were placed in 11 shelters, each of which had
a different A. robusta individuals. The film quality was
generally excellent, including good lighting (Fig. 5), and a total of
850 hours of video footage with an A. robusta in view was
generated. Eight individuals stayed longer than 5 days in a chamber that
was being filmed, while three stayed over 30 days. This suggests that
the camera was accepted by the frogs, and not a source of disturbance.
In addition to frogs, various other species sought refuge under the
artificial shelters and were captured in the video footage. These
included other small vertebrates (skink species) and invertebrates such
as ants, earthworms, velvet worms, cockroaches, and millipedes.
Although the cameras were thoroughly tested before being deployed in the
field, a few issues arose during field testing. In two camera setups,
the dates and times displayed on the video files were inaccurate after
batteries were replaced. To resolve this issue, we reran the codes for
the clock, which successfully fixed the problem for one camera. However,
we had to replace the clock module in the other camera. In one camera
setup, the brightness of the Infrared LED light decreased in some videos
before eventually turning off. This occurred towards the end of the
expected video duration and was likely due to the lower voltage
available. The issue was resolved by changing the battery and always
using fully charged batteries. The final issue was that despite
adjusting and testing each camera’s focus before deployment, some
cameras produced out-of-focus video. This was primarily attributed to
the camera sliding down too deep (and hence out-of-focus) in the shelter
setup. This was sometimes due to the camera hole in the artificial
shelters being slightly wider than the camera PVC pipe, causing the
camera to slide down too far. In other cases, it appeared that the
camera had been moved during filming, probably due to disturbance from
wildlife such as brush turkeys or feral pigs. To address these issues,
we applied multiple layers of Duct tape around the camera PVC pipe to
secure it in place and prevent any sliding or moving. Another common
cause of unfocused videos was the gradual elevation of the soil beneath
the camera due to the burrowing behaviour of earthworms, but this could
not be prevented.
We initially envisaged that the camera setup could be damaged by
moisture. They were sitting in a wet rainforest environment with regular
heavy rain, and the 62 battery and USB drive changes were all performed
in >90% humidity and sometimes during rain. However, no
water damage was observed on the cameras, batteries, or USB storage
drives. This was even the case for one of the cameras which spent time
with its lens end underwater when one of the chambers was flooded during
heavy rain. The camera kept recording and was not damaged.