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. These are my posts so far: Rock-dwellers #1, Rock-dwellers #2 Burrowers #1, Vegetation-dwellers #1.
This second group of burrowers is awesome! Two of the dragons in this group are absolutely spectacular in terms of colour and behaviour, and the other two are mysterious beasts that are little known, rarely seen dwellers of Australia's most unforgiving habitat: salt lakes. They all dig cute little burrows and duck into them if they feel threatened.
They are among my absolute favourite things to chase, which is great because this is the only group that we went chasing all three seasons of fieldwork. We started off chasing painted dragons at the very beginning of my very first field season and we ended my very last field season chasing claypan dragons over two years later.
Painted Dragon (Ctenophorus pictus)
Painted dragons live up to their name. They are gorgeous! The males have brightly coloured heads that are blue, red, orange or yellow, along with a beautifully coloured and intricately patterned backs. The females are also quite intricately patterned, but they are not brightly coloured like the males. This is one of the first species we chased back in September 2011, and we had so many problems! It was a huge challenge just to catch one, and often it took three of us all surrounding the same tree to get a lizard. The trouble we were having had me worried for the rest of my fieldwork. Would we be able to catch enough lizards for my project to work?
We needn't have worried. The problem wasn't that that painted dragons are hard to catch, it was that we sucked at catching painted dragons! By 2012 we'd had a lot of practice, and we were hoovering them up. It turns out painted dragons are among the easiest dragons to catch, owing partially to their habit of sitting conspicuously on the tops of bushes.
Male painted dragon, Ctenophorus pictus. Turlga Station, South Australia, 2012. Photo by Angus Kennedy.
Female painted dragon, Ctenophorus pictus. Turlga Station, South Australia, 2012. Photo by Angus Kennedy.
Claypan Dragon (Ctenophorus salinarum)
Who knows why they call these things claypan dragons. They don't live in claypans, which are basically dried-up ponds. They live in salt pans, which are basically dried up salt lakes. When it's wet in the Australian scrub, like it was when we were looking for these guys in October 2013, they live on the salt crust around the edges of filled salt lakes. It's a very narrow strip of land, and makes their suitable habitat almost two-dimensional.
Claypan dragons have a reputation for being hard to find. There are few records of them in the Atlas of Living Australia and almost nothing about them in the published literature. Maybe they have this reputation because people keep looking for them in claypans, because we had no troubles! Before my fieldwork I was worried that we'd have a lot of problems finding these guys. As it turns out, we came across them completely by accident while visiting a tourist spot before even starting our search in earnest! We did have trouble finding lakes where they lived. We visited a lot of lakes where we'd walk all the way around the lake and not find a sign of the dragons. However, when we visited a lake and found one, we'd find another, and then another, etc. They live in impressively high densities where they do live, it just seems that they're picky about which lakes they live around. Someone should use science to figure out why!
Male claypan dragon, Ctenophorus salinarum. Varley, Western Australia, 2013. Photo by Angus Kennedy.
Female claypan dragon, Ctenophorus salinarum. Varley, Western Australia, 2013. Photo by Angus Kennedy.
Lake Disappointment Dragon (Ctenophorus nguyarna)
These critters live in the middle of absolute nowhere. They was discovered by accident in 1996 when a vehicle full of scientists became stuck in the mud on the edge of Lake Disappointment. Lake Disappointment is so named because if you are wandering, lost and dehydrated, in the desert and see Lake Disappointment in the distance, you will think that you're saved. You will be wrong, disappointed, and more likely than not you will shortly be dead. Lake Disappointment is a salt lake and no one's saviour, except perhaps for the Lake Disappointment dragon's. Due to their remoteness we did not go after this dragon during my fieldwork.
Bicycle Dragon (Ctenophorus cristatus)
It's not completely clear that the bicycle lizard belongs in this group. When Greer wrote his book back in the 1980's, he included them in the burrowers, but Melville (2001) places them among the vegetation dwellers. Since the vegetation dwellers don't have a burrow or crevice close by for security, they tend to be long-legged, dainty things that are very good at taking off at high speed. The bicycle dragon certainly fits this bill. They're called bicycle dragons because, when scared, they lift up into a T-rex position, pin their front legs against their chest and rotate their back legs as if they're peddling a bike. This gets them far, fast.
But back to the burrowing. According to the most recent phylogeny (Chen et al., 2012), bicycle dragons are part of this group of burrowers. However, Chen and her colleagues can't be completely sure of this relationship, according to their statistics all they can say is that the bicycle lizard is probably part of this group (thanks to JP for clarifying the meaning of phylogenetic probabilities). Of the four phylogenies published on Ctenophorus over the past fifteen years, none have placed the bicycle dragon in the same place. So the genetics, at the moment, are inconclusive.
What about practically? Do bicycle dragons actually dig burrows? Greer, in his 1989 book "Biology and Evolution of Australian Lizards", says yes. However, others since then have said no, mostly citing personal comments and observations (eg. Meville et al., 2001; Thompson & Withers, 2005). During my fieldwork, we probably caught about forty bicycle lizards, and had another twenty or so escape on us. Not a huge sample size, but not small either. The vast majority took off as I described above. One individual ducked into a burrow. Compare this to the other burrowers we caught: the painted dragon, claypan dragon, and central netted dragon. The painted dragon would duck into a burrow probably around 80% of the time, the rest of the time taking off running or ducking under a bush. The claypan and netted dragons, which live in more exposed habitats than the painted dragon, ducked into burrows close to 100% of the time. So are bicycle dragons burrowers? Maybe they're facultative borrowers, building burrows when it suits them. This is another question that science is a very useful tool for answering.
Male bicycle dragon, Ctenophorus cristatus. Lake Hurlestone Conservation Reserve, Western Australia, 2013. Photo by Angus Kennedy.
Female bicycle dragon, Ctenophorus cristatus. Lake Hurlestone Conservation Reserve, Western Australia, 2013. Photo by Angus Kennedy.
References
Chen, I, Stuart-Fox, D., Hugall, A.F., and Symonds, M.R.E. 2012. Sexual selection and the evolution of complex colour patterns in dragon lizards. Evolution, 66-11:3605-3614.
Greer, A.E. 1989. The biology and evolution of Australian lizards. New South Wales: Surrey Beatty and Sons.
Melville, J, Schulte II, JA, and Larson, A. 2001. A molecular phylogenetic study of ecological diversification in the Australian agamid genus Ctenophorus. Mol Dev Evol., 291:339-353.
Thompson, GG and Withers, PC. 2005. The relationship between size-free body shape and choice of retreat for Western Australian Ctenophorus (Agamidae) dragon lizards. Amphibia-Reptilia, 26:65-72