Frilly in the Flames

Caught with appropriate permits for scientific study; photographed when released [5]

Out of all the variation in body injuries and tearing of the frill, this individual frillneck lizard (Chlamydosaurus kingii) had the most bizarre condition— a seemingly seared edge of the frill, blackened with shriveled scales. When collecting her at night I didn’t notice this abnormality, but the following day I finally realized what was the most probable cause. Her nocturnal perch of choice was surrounded by charred eucalypts from a recent fire. Given the frequent fire regimes in the savanna woodlands of the Northern Territory, it’s possible the edge of her frill caught on fire. The imagery of a frillneck falling from the canopy and blitzing across the grasses with a burning frill sounds surreal, but evidently this female was able to survive the flames. Another small piece of evidence was that along her dorsum I could pick out a faint charred scar that perfectly lined up with the edge of her frill when apposed to the body.

Although this scenario might sound like a freak occurrence, in tropical woodland habitats dominated by eucalyptus, fires are commonplace. Some populations of frillneck lizards even experience ~30% mortality during late dry-season fires. In plant communities, fires create heterogeneity in species composition and habitat succession, for example by allowing understory shrubby vegetation to thrive within otherwise dense forest canopies. This spatiotemporal mosaic, in turn, heavily impacts invertebrate and vertebrate species abundances. After fires, exposed invertebrates attract all kinds of insectivorous predators, most notably birds of prey. Remarkably, Australian kites and falcons have been documented to spread wildfires by transporting cinders to unburnt areas. This behavior has been widely known by indigenous peoples for centuries, and a few years ago a study was published incorporating observations throughout the NT, WA, and Queensland. However, the claim that the raptors intentionally spread fires to reap the rewards of fleeing arthropods remains controversial.

Frillneck lizards, likewise, benefit from fires; one study found greater prey volume and diversity in the stomach contents of lizards exposed to forest fires. Although the frill has been previously implicated in a variety of potential functions (e.g. parachuting, food storage, thermoregulation), maybe a new function to be debunked is for the frill to catch and spread fires. It remains to be determined whether the lizards fan their frills in and out to throw flames into different patches of vegetation— just to be clear, this is a joke! Stay tuned to see my publication about antipredator behavior in the frillneck lizard in print very soon. But… read here about the Dreamtime tale of Ga’ni the lizard; how the brave frilly scarred its chest to set further lands ablaze.

Dreamtime Kullilla-Art by Michael J Connolly

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