House Possum

There used to be a small family of common brushtail possums ("brushies") living in the walls of my house in Canberra. They squabble quite a bit (or at least it sounds like squabbling), so we knew when they were home. We never did anything to discourage them from living with us, but lately it's been pretty quite and I think they've moved house. Nonetheless, they're still around. The mother has always been the tamest of the family, and when I hang my laundry outside after dark she'll often come up to me and give me a sniff. She's pretty happy being patted as well, as long as I move slowly and don't do anything to spook her. Someone probably feeds her, but I don't.

A member of the brushtail family feeding around my house. A visiting researcher who had spent four months in Australia without seeing a brushy can be seen in the background, fulfilling her dream on her last night in Canberra.

A member of the brushtail family feeding around my house. A visiting researcher who had spent four months in Australia without seeing a brushy can be seen in the background, fulfilling her dream on her last night in Canberra.

Recently, the mother brushy had a new baby emerge from her pouch. Brushies are marsupials, so babies are born tiny, pink, and useless. They mature in their mother's pouch, protected from the harsh world and consuming only their mother's milk. Once they have eyes, fur, and various other things possums need to survive, they leave the pouch and ride around on their mother's back for a while. That's what I saw when the mother brushy came running up to me while I was hanging laundry last night.

Burrowing Dragons, group 1

In his book "Biology and Evolution of Australian Lizards", Allen Greer sorted the lizards I study, the genus Ctenophorus, into different groups based on where they live: those that live in burrows, those that live in rock crevices, and those that live in vegetation. Looking at the phylogenetic relatedness of the Ctenophorus dragons, there are two groups of each: two groups of burrowers, two groups of rock-dwellers, and two groups of vegetation-dwellers. I thought it'd be fun to put up pictures and descriptions of all these groups, since I have a large pile of pictures from my fieldwork. Here is my first post, on the first group of rock-dwellers. 

Since I started with a small group, why not continue the trend? The first group of burrowers also consists of only two species. In sharp contrast to the two rock dragons, however, these two look almost identical. They're both called "netted dragons" because it looks like someone's taken a plain-coloured dragon and tied a fish-net stocking over it. I guess they're rather kinky fellas. 

Though they're both named for their geographical distributions, as the central and western netted dragons, in reality their ranges overlap quite extensively. The central netted dragon is found over a huge swath of Australia, as can be seen in the map below which I screen-grabbed from the Atlas of Living Australia. The western netted dragon is more restricted to southwest Australia, but is still found over a huge area. The atlas is not perfect, and some of these points are almost certainly erroneous. For example, the central netted dragon record from Brisbane and the western netted dragon record from Katherine.

The ranges of the central (in green) and western (in brown) netted dragons, according to the records of the Atlas of Living Australia.

Central Netted Dragon (Ctenophorus nuchalis)

The central netted dragon (Ctenophorus nuchalis) is one of Australia's most recognisable and ubiquitous lizards. The only lizards I can think of that beat the central netted dragon in these two categories are the bearded dragons (Pogonas vitticeps and barbata). Maybe the bluetongues of the genus Tiliqua. Though central netted dragons may not be quite as ubiquitous or famous as those critters, they share many of the same characteristics. They are tough as nails, live happily in the harshest habitats Australia offers, and make wonderful pets. They are easy to breed in captivity and are regularly available in the pet trade in Australia.

A hatchling central netted dragon that was bred here at the ANU. Central netted dragons are easy to breed and make excellent pets. Photo by Lisa Schwanz.

Central netted dragons are found across a wide variety of habitats here in Australia, but they seem to be at their densest in red sand country. Driving along a dirt track in a sandy area of central Australia can give you the impression that these guys exist in plague proportions. Because they are so common, they are well known to the people who live in the Australian outback. When I showed some cattle ranchers what we were looking for, they knew the lizards quite well and referred to them as "gumby lizards" apparently because of their dumpy heads. They love to sit along the side of dirt tracks, on that little elevated mound of dirt made by the grater as it smooths out the road (about the same thing as what a snow plow used to leave on my driveway back in Canada, after I'd already shovelled it.) Being burrowers, they'll usually have a little burrow in the mound, which they'll duck back into if they feel threatened. 

A red dirt track with sand ridges makes perfect central netted dragon habitat. Henbury Station, Northern Territory, 2012.

Western Netted Dragon (Ctenophorus reticulatus)

The other species in this group of burrowers, the western netted dragon (Ctenophorus reticulatus), looks very similar to the central netted dragon, to the point where you have to examine the shape of their femoral pores to be sure of which species you're looking at. However, western netted dragons are a heck a lot rarer than central netteds. We spent a fair amount of time in western netted dragon territory during my fieldwork, and in that whole time, every netted dragon we ever caught was a central. In 2013 we spent a week doing research outside the range of the central netted dragon, so every netted dragon we saw was pretty much guaranteed to be a western. In that week, I saw two lizards I was pretty sure were netted dragons. Both times we failed to catch the dragon, so I'll never know for sure if I've ever seen a western netted dragon. Good thing we didn't need them for my PhD!

Rock Dragon Group 1

About a month ago (!) I decided to start putting up pictures of the dragons I study, sorting them into the habitat groups originally described by Greer in the 1980's. This is a useful way to think about the dragons because, according to their evolutionary relationships, there are two phylogenetically conserved clades of each habitat group: two groups of vegetation-dwellers, two groups of rock-crevice dwellers and two groups of burrowers. By going through these groups one-by-one, it gives me a nice way of posting some lizard pictures, some habitat pictures, and breaking it all up into decent-sized chunks.

Let's start with a small group. This is the small group of rock dragons, with only two species. They also, despite being each other's closest living relatives, look almost nothing alike. 

Ornate Dragon (Ctenophorus ornatus)

Ornate dragons are colourful - the ones we were catching looked almost purple, especially the males - intricately patterned and extremely laterally depressed. These were the flattest out of all the species we chased. They used their particular flatness to wedge themselves into the most impossibly narrow crevices in the granite rocks on which they lived. Granite weathers in this peculiar way where the water trickles just underneath the outmost surface of the rock, creating "exfoliations" that are rather like dissecting an onion one layer at a time. The very very narrow crevices created by the exfoliations are the primary means of shelter for these dragons, making them very difficult to catch.

Ornate dragons are incredibly common on granite outcrops in southwest Western Australia. Their ubiquitousness has made them a model organism for studying optic regeneration in lizards. In any animal, if you sever the optic nerves that connect the eyes to the brain the animal becomes blind. This is despite the animal still having fully functional eyes and fully functional vision-processing brain regions. In mammals, this blindness is frustratingly permanent as the optic nerves don't regenerate, leaving the eyes permanently disconnected from the brain. In lizards, however, the optic nerve does regenerate, reconnecting the eyes with the brain. But here's the weird part: the lizard never regains its vision, despite the reconnection, and eventually the connection degenerates again. How very, very strange. Unlocking the mechanisms behind the reconnection, and trying to figure out how to get vision up and running again in these lizards may be the first step to helping people with this particular form of blindness get their sight back.

Ring-tailed Dragon (Ctenophorus caudicinctus)

Ring-tailed dragons look more like what I think of as a standard, normal-looking dragon compared to the ornate dragons. For example, they have square heads and are not particularly flat. Yet they still live in rocky areas and shelter in rock crevices. The rocky outcrops they live on, however, seem to weather into liftable-sized chunks rather than large, flat exfoliations, and as a result the crevices they shelter in are not nearly as narrow. That's because, at least where we were looking for ring-tails, they live on rocky outcrops made of sandstone instead of granite. This makes them quite easy to catch, but it turned out during my fieldwork that though catching ring-tailed dragons was not an issue, finding them was.

Ring-tailed dragons occupy a huge swath of central and western Australia, and I used to think of them as being quite common. They're the only species of Ctenophorus I'd seen before starting this PhD. That's because they're very easy to find in Watarrka and Kakadu National Parks, two very popular vacation spots I visited as a tourist in 2005. So when we started my fieldwork in 2012, I was not expecting to have a problem finding them. It turns out, however, that ring-tails are not so easy to find outside of national parks. We scoured rocky outcrops, struggling to come up with any dragons. We did eventually find all the lizards we needed for my project, but it took a heck of a lot longer than I was expecting, and we spent a lot of time driving huge distances checking out possible locations. It's extremely hot out there, and spending all day scrambling over rocks, searching for tiny brown lizards that you just can't find, is pretty disheartening. When we did start finding them, we got pretty excited:

Brown snake on campus!

We had a bit of excitement in the biology department today as a juvenile eastern brown snake (Pseudonaja textilis) paid our building a visit. It was first seen (not by me) just inside the building, but it made a quick retreat back outside.

This little brown snake paid us a visit today.

Our building's safety officer (in blue) evaluating the situation. In the background is the Banks Building, where I and about half the Department of Evolution, Ecology & Genetics have our offices.

We followed the snake until it hid in some bushes. We left it there in hopes that it will make its way back to some nearby bushland where it will be safe from mean people with long sticks. Hopefully we won't come to work tomorrow to find a squashed baby snake!

The young brown snake found temporary shelter in a bush near our building.

Sorry for the poor quality of these pictures, but that's something to be expected from me photographing deadly snakes.

Taronga Zoo is displaying my dragons!

Two of the dragons we collected as part of my research are now in display at Taronga Zoo in Sydney! We collected the central netted dragon on Henbury Station in the Northern Territory in 2012 and the red-barred dragon on Mulgaria Station in South Australia in 2011. Both dragons are visible in the picture below. The central netted dragon is obvious, while the red-barred dragon is a little harder to find.