Ornithology from the Lakeshore

Abstract

strophic, and depend on the context and on our level of control. The progression of our species is deeply linked to our inventiveness in gaining control over fire. We ingeniously moved combustion inside of machines and thereby enabled the development of a society on steroids. Unfortunately, the negative consequences have become all too apparent. Using coal, oil and gas as incendiary resources, we have burned ourselves into a global crisis. So much so that the current geological epoch has been called the Pyrocene (Nimmo et al. 2021, Pyne 2021). Among the multifarious consequences of the pursuits and practices of the growing population, out-of-control wildfires have become one of the most terrifying and destructive natural disasters. You may remember how in 2020 a bushfire raged in Australia turning an area larger than Belgium and The Netherlands combined into ashes. News reports abound headlining furibund fires, even in the Arctic. As Covington & Pyne (2020) put it, “It can seem like Earth itself is on fire”. Although the frequency, scale, severity and intensity of fires may be increasing globally, let us remind ourselves that fire has shaped terrestrial ecosystems long before humans were present on Earth. Every year an estimated 3% of the global land area burns, or about 400 million hectares of land (Forkel et al. 2019). Thus, we also need to consider fire as a fundamental force in evolutionary ecology (Kelly & Brotons 2017, Pausus & Parr 2018). As is well known, plants have evolved a variety of traits that enable them to flourish and flower under recurrent fires (Keeley et al. 2011). However, the role fire has played in the evolution of the life history and behaviour of animals still remains underexplored. In an insightful review, Pausus & Parr (2018) highlight several key questions that need to be addressed to improve our understanding of the evolutionary role of fire in animals. They distinguish fire-adapted animals – those that have evolved traits that are shaped by fire, including the eager urge to escape from it – and firedependent animals, a more select group that needs (or at least opportunistically uses) the resources generated by fire for survival or reproduction. In the following, let me highlight a few fascinating examples of fire dependency from the feathered world. The most rational and common reaction to a raging fire is to flee from it. Animals are generally welladapted to recognize the tell-tale signs of fires (where there is smoke...) and will either hide in a safe place or move away swiftly to avoid a certain death. It is precisely this judicious response that is exploited by some predatory birds. On different continents, numer ous raptor species have been observed to make their way to the edge of the blaze where they often congregate in large numbers, in anticipation of a richly stocked, albeit moving, buffet. In a remarkable example of niche construction, Black Kites Milvus migrans in the Northern Territory of Australia self-cater a buffet of small mammals, reptiles, and insects by spreading the fire themselves. Aboriginal people presumably have known for a long time that some raptors, including Black Kites, Whistling Kites Haliastur sphenurus and Brown Falcons Falco berigora, occasionally pick up a burning branch in their talons or beak and drop it elsewhere to ignite a fire. The tool-use behaviour of these ‘firehawks’ has been witnessed by Australian fire fighters and a few scientists (Bonta et al. 2017). Apparently, the behaviour has not yet been documented on photo or video, and although Bonta and his colleagues do not doubt it, they admit that scepticism remains about whether the birds intentionally, rather than accidentally, spread fire. Who knows whether our ancestors learned to use fire from observing avian arsonists? Bird watching provides many benefits, but also has many practitioners. So, one wonders how exceptional this behaviour is, why it has not been better documented, and why it does not seem to occur elsewhere on the planet. Birds of various plumes and predilections are attracted not by the fires themselves but by the resources that become available in recently burned areas. For example, hummingbirds and other nectareating species may be drawn to the post-fire explosion of flowers, whereas predators may benefit from hunting under upgraded spot-and-track conditions provided by the newly created open habitat. Arguably the best studied ornithological example of fire dependency is the case of the aptly named Black-backed Woodpecker Picoides arcticus in western North America. Blackbacked Woodpeckers are found in coniferous forests and bogs with dead trees, and often in areas that Ornithology from the Lakeshore