29th June 2023 |
Written by Dr Susan Quinnell of Tramway Hill Landcare Group
There is a revolution in wildlife conservation: we can now monitor vertebrates in difficult places and over large areas using ‘camera traps’ that operate day and night.
This article is about ‘camera trapping’ and its findings in a small valley of southern Tasmania. Cameras were run here for 4 weeks in autumn to winter at each of 13 ‘sampling locations’ along 3 km on Nierinna Ck Valley with another camera nearby in a dry woodland to act as a ‘reference’. Collectively, cameras ran for ~10,100 hours. Some were placed to monitor Nierinna Ck, others within grassy paddocks, open forest, and a dry open woodland. We obtained about 5,000 images of animals and about 60,000 images of waving grass (cameras are activated by movement).
Ideally, cameras are mounted on star pickets. However, usually this was impossible as Tasmania here is largely composed of dolerite rock, hard as diamonds and in the form of immovable boulders. Therefore, we attached 9 cameras to trees. Ahhhh! The common brushtail possum lives in trees, Thus, cameras were prodded, licked, and turned upside down. Consequently, we have photos of possums, possum paws, whiskers, ears, mouths and even eyes as well suddenly tilted views of the landscapes. (Mounting cameras on rocks is also not a good idea as Tasmanian devils are known to test their ‘bite force’ on ground-located cameras.)
We used a lure of tuna oil. It certainly attracted brush tail possums. Nightly they returned to sniff, paw, and scrape at the smelly ground. Eastern quolls and potoroos also were enticed, but not so much Tasmanian devils, eastern barred bandicoots, pademelons, and red-necked wallabies. The cameras tell us what is present, but not accurately how common each species is. However, the findings are exciting.
Tasmanian devils were photographed at 5 camera sites. There are eastern quolls throughout the valley as well as numerous eastern barred bandicoots and potoroos. In contrast, brown bandicoots were seen just twice. Brushtail possums were everywhere, but not common in the dry woodland. The pademelon and Bennet’s wallaby are widespread. An unexpected finding was a water rat in Nierinna Ck. In short, Nierinna Ck Valley’s larger native mammals are doing well. This is remarkable because by 1965 much of the valley had been cleared and today’s forests where cameras were placed consist of regrowth trees, except along the creek there are few old trees and therefore few hollows and large fallen logs to form animal shelters.
We know there are mammals here not recorded (we see them), including bettongs in the drier forests. There is evidence that spotted tail quolls pass through sometimes. Echidnas and platypus are common, but have a somewhat low body temperatures and rarely recorded by camera traps. And, of course, there are feral cats.
Photographs from this study are being sent to Tasmanian Land Conservancy for incorporation into ‘Wildtracker’. This Citizen Science project could be repeated anywhere. The data are valuable.