Karen Rowe: So we use a lot of different methods to survey mammals. We do cage traps, which are sort of wire mesh traps that the animals wander into with a little bit of bait, we use live Eliott traps which are metal traps that work on the same mechanism but they keep the animal in the trap alive until we can check and see what they are and then often we will release them.
We use acoustic recordings for bats in particular; we have these systems called Anabats that do recordings over a 12-hour period at night. Out in the field the only way to see things like kangaroos and wombats is to walk around, they won't wander into our traps. So we do a lot of direct observations and we get everybody to help us with that 'cause it takes a lot of people to get a good assessment of the wide spaces that exist in the Prom. So we look for footprints, we look for scat, we look for scrapings, we look for digging holes and things like that
Karen Roberts: These are some of the specimens that we collected and took voucher samples of, So we have Antechinus swainsonii, also known as the Dusky Antechinus; Rattus lutreolus, the Swamp Rat, and Rattus fuscipes which is the Bush Rat and that was the most commonly-caught animal in our traps. We collected ten Bush Rats which was the maximum number for our permit, and we got a good sample also of the Swamp Rat.
We were also lucky to collect a few antechinus specimens however we didn't get as many of those. The antechinus at this time of year the antechinus have just gone through their breeding cycle so most of the males, which only live for about a year, they've already mated and they die more or less straight after they've mated.
These two are in the same genus so they're relatively closely related but the antechinus is a marsupial . They're all native Australian animals even though these are rats and they have quite different reproductive methods. Many of the dasyurid, or the small insectivorous marsupials, don't actually have a pouch. In this case the antechinus has like a, creates a sort of flap of skin that protects the young when they're very small. But of course it's closely related to all the other marsupials, like the kangaroo and koala which have pouches unlike the rats which are eutherian mammals or placental mammals.
Karen Rowe: One of the ways we can tell the difference between the Bush Rat and the Swamp Rat, which is this one, is the difference in the tail length. So you can see the Bush Rat has a much longer tail than the Swamp Rat and actually one way we tell is how long the tail is relative to the body. So it's not just the actual length but it's the relative length. The Swamp Rat has dark feet on the top whereas the Bush Rats have very light feet on the top. The Swamp Rats tend to be more grizzled looking and they kind of look different in the trap too so when you look at them often you can see a difference in the face but that's something that's not really diagnostic, it's just you get the rat gestalt after a little while.
In Wilsons Prom the Bush Rat is the one species that we found in every single site and every trapline. So they inhabit open forest, closed forest, wet forest, swamps, everything, you name the habitat and they're there. The Swamp Rats are much more restricted to swamp habitats. We caught them mostly at Sealers Cove.. what were some of the other sites...Darby River...
Karen Roberts: ...and Lilly Pilly Gully
Karen Rowe: ...and Lilly Pilly Gully. The number of animals we catch is not necessarily reflective of their population abundance because it has a lot to do with where we set our traps and how long we're out there and such, but it's pretty clear that we know that the Bush Rats are found throughout the park and that's good, they're the native rat of the area.
It was such a short period of time, it's really hard for us to make any strong statements about the community in general, the mammal community in general. We would need significantly more time out there to really get a good handle on what other species are present that we may not have detected this time around, particularly things that, like antechinus is notorious for taking a few days to get used to the traps so you oftentimes won't catch new species until a few days in and a lot of the sites we were at we were there for two, three, up to four at the most days and we generally run mammal traplines for four days plus. So it would take another I think more thorough survey to really get a good handle on that. But we didn't see many invasive species in terms of rodents. We saw other ones like hog deer, rabbits...
Karen Roberts: foxes, cats
Karen Rowe: ...foxes, one cat, so they're known to be present. It doesn't seem like the flood has affected their presence at least for the mammals, it just seems like what's going on is what's been recorded in the past.