The Science of Birds - Fire and Birds

Episode Date: December 7, 2021

Ecologists and ornithologists have been studying the effects of wildfire on bird populations all over the world. Their research has resulted in many fascinating discoveries about the relationships between fire and birds.Wildfires have been in the news a lot in recent years. In the western US where I live, enormous fires have been sweeping across California, Oregon, Idaho, and other states with increasing frequency and severity.And who can forget the 2019-2020 bushfire season in Australia, which came to be known as the “Black Summer?” Then there were the thousands of fires that broke out in the rainforests and wetlands of Brazil in 2020.This is all pretty bad news, no doubt. It can be gut-wrenching to watch beautiful wilderness go up in flames, not to mention towns and people’s homes. But if we temporarily set aside our emotions, we can take a more scientific, objective viewpoint to ask the question: Are wildfires harmful to birds and other wildlife, in general? It turns out there’s no simple “yes or no” answer to that question. ~~ Leave me a review using Podchaser ~~Links of InterestOld Flames: The Tangled History of Forest Fires, Wildlife, and PeopleBringing Back the Red-cockaded Woodpecker: Are Prescribed Fire and Artificial Nests Enough?New Study Is First to Explore How Wildfire Smoke Derails Bird MigrationThese Birds of Prey Are Deliberately Setting Forests on FireSupport the show

This past summer, my wife Cassandra and I took a road trip down to Arizona. We camped and went birding in several of the small mountain ranges in the regions surrounding the city of Tucson in the southeastern part of the state. These mountains are rich in biodiversity, including birds. Southeastern Arizona is actually a major bird-watching hotspot in the U.S. It's a magical place, home to special birds like the elegant trogon, Arizona woodpecker, Mexican J, red-faced warbler, and blue-throated mountain gem, which is a hummingbird. My first experience exploring this region was in 1999, when I worked as a volunteer research assistant in the Chiricahua Mountains. Of the dozens of small, isolated ranges in the region,

the Chirikawa's are the largest and most biologically diverse. I spent the summer of 1999 hiking around in the high country of those mountains, at elevations around 9,000 feet. or 2,700 meters. The forest up there was a lush mixture of pines, furs, and aspen trees. Beneath the trees, the undergrowth was thick with shrubs, wildflowers, and mushrooms. Fast forward 22 years to my recent trip with my wife. After over two decades, I had finally returned to the higher reaches of the Chiricawa Mountains. And you know what?

I hardly recognized the place. The forest was much thinner than I remember, and the trees smaller. Unlike the dense, shady forest of my memory, bright sunlight was shining between the trunks now, and many slopes were relatively bare of trees altogether. Was I shocked to see this dramatic transformation? No, not at all. I already knew what had happened. In the summer of 2011, a massive fire erupted in the Chirikawa Mountains. It raged for about six weeks and scorched over 224,000 acres, which is about 91,000 hectares. Almost the entire mountain range burned. It was a heartbreaking disaster in the eyes of many people who love the

wildlife and birds of the Chirikawa's and southeastern Arizona. The charred forests of those mountains would take many more decades, if not centuries, to return to their former glory. My visit this summer was ten years after the fire, but evidence of the destruction was still obvious almost everywhere I looked. Yes, the forest is recovering, but like I said, it's going to take a long time. Seeing such a sweeping change to the ecosystem, one of my first thoughts was, how did the 2011 wildfire affect the birds of the Chiracawa Mountains? I mean, historically, this has been a great place to see a wide diversity of bird species. Is that still the case? Or are there fewer species now? And has there been a great place? And has there been a great place to see a wide diversity of bird species? And has

there been any change in which species live there? Thanks to hardworking scientists, there are actually some answers to these questions. We'll come back to the Chiricawa Mountains at the end of the episode. But first, let's take a wider view. Ecologists and ornithologists have been studying the effects of wildfire on bird populations all over the world. Their research has resulted in many fascinating discoveries about the relationships between fire and birds. Hello and welcome. This is the Science of Birds. I am your host, Ivan Philipson.

The Science of Birds podcast is a lighthearted, guided exploration of bird biology for lifelong learners. This episode of the podcast is all about how birds are affected by one. wildfires. Now, if you've been listening to Smokey the Bear and Frankenstein's monster, not to mention the news media, you know that fire is bad, right? Fire bad? Birds good. But it's not actually as simple as that. Well, sure, birds good. No one can argue with that, but fire? Fire is complicated. From a human perspective, wildfire can be absolutely horrific when it devastates communities and claims lives. Wildfires have been in the news a lot in recent years. In the western U.S., where I live, enormous fires have been sweeping across California, Oregon, Idaho,

and other states with increasing frequency and severity. And who can forget the 2019-2020 bushfire season in Australia, which came to be known as the Black Summer. Then there were the thousands of fires that broke out in the rainforests and wetlands of Brazil in 2020. Fires, fires, and more fires. This is all pretty bad news, no doubt. It can be gut-wrenching to watch beautiful wilderness go up in flames, not to mention towns and people's homes. But if we temporarily set aside our emotions,

we can take a more scientific, objective viewpoint to ask the question, are wildfires harmful to birds and other wildlife in general? It turns out there's no simple yes or no answer to that question. The answer is complex, so let's see what we can figure out. Wildfire has been a natural phenomenon on Earth for about 400 million years. Lightning and volcanic eruptions are the primary sources of ignition. Well, that was until we came along and started roasting marshmallows, lighting firecrackers, and tossing cigarettes out of car windows.

Fires are in the same category as hurricanes, floods, volcanoes, storms, avalanches, and landslides. Each of these is what ecologists call a disturbance. A disturbance causes a dramatic change to an ecosystem, which then recovers over some period. Decades, centuries, or millennia. A recovering ecosystem may or may not end up returning to its former state, to what it looked like before the disturbance. Natural events like floods and fires have been occurring for so many millions of years that life has, in many ways, adapted to them.

In fact, many ecosystems actually depend on these periodic disturbances. Wildfires are an essential feature of ecosystems like grasslands, coniferous forests, shrublands like chaparral, oak woodlands, and eucalyptus forests. Many of the plants in these ecosystems need fire in order for their seeds to germinate and to clear away their competitors. There's so much going on with wildfire dynamics and how fires shape both, ecosystems and wildlife populations that an entire field of scientific research has emerged. It's called fire ecology.

Fire ecology is a broad and fascinating subject. Naturally, we're just scratching the surface here today, or scorching the surface, I guess you could say. But in order to understand how wildfires affect birds, it's helpful to know a little something about fire ecology. One thing we need to talk about is the fire regime. No, I'm not talking about some evil empire in a series of dystopian young adult novels. Rather, a fire regime is the long-term pattern of wildfire frequency, distribution, and severity in a given region. Let's say we're considering a particular hypothetical mountain range.

For the last 3,000 years, a natural wildfire must be a natural wildfire might occur there on average every five years. Those fires may tend to be of low severity and moderate spatial extent. All of that would more or less describe the prevailing fire regime of those mountains. Over many years, fires burning here and there across a landscape end up creating a mosaic of distinct habitat types. There might be some undisturbed patches of, let's say, old, dense forest. But nearby there are sunny bear patches full of shrubs and young trees,

and there are other patches of forest of an intermediate age. This patchwork, this mosaic, shifts and moves around endlessly on the landscape over long time scales. Mosaics of habitat like this can also be created by a single wildfire. Even the largest fires don't always uniformly reduce everything in their path to ashes. A fire may move haphazardly across the landscape and with varying intensity. Once the fire is out and the last embers have cooled, the result might be a patchwork of charred, barren areas mingled with lightly toasted areas and some that were completely untouched.

Some research even suggests that large, severe fires are exactly what is needed to create the full spectrum of habitat conditions used by birds. Whether a mosaic of habitats was created by one fire or a series of fires, the result is generally the same, a greater diversity of plant and animal species living in the affected ecosystem. That is, compared to what you find in a relatively uniform and, dare I say, uninteresting landscape, one blanketed by just a single habitat type. Boring! When there are more habitat options available, more species can find comfy

places to make their homes and their lives are more interesting. Now, I should point out that all of this assumes that the ecosystem we're talking about is one that has evolved with fire for thousands or more likely millions of years. But this is pretty cool, right? This is one major discovery from the world of fire ecology. Wildfires operating under natural fire regimes often increase the overall diversity of life in an ecosystem. The idea here even has a name. It's called the pyro-diversity-biodiversity hypothesis. Pyridiversity is a cool word that describes the complexity of a given fire regime,

in terms of fire frequency and intensity. Many studies have found evidence that supports the pyro-diversity-biodiversity hypothesis. But, of course, it has its critics, and there's still plenty of debate among scientists about how universal this phenomenon might be. Even when wildfires tend to generate more biodiversity, not all plant and animal species respond in the same way. Some are well adapted to fire and will even thrive after a burn. Others are completely vulnerable to it. So depending on which critters you're talking about, wildfire might be a force of destruction or of rejuvenation. We, of course, are interested in

birds. Let's finally get specific and talk about birds and how they deal with fire. When a wildfire roars onto the scene, most birds have a big survival advantage. To escape the flames, they can simply fly away. You can't say the same about turtles, raccoons, or monkeys, can you? So direct mortality due to fire is probably less common in birds compared to other land-dwelling vertebrates. However, when fires happen during the breeding season, eggs, nestlings, and fledglings may be in serious danger. But rather than dwell on the question of who lives and who dies in wildfires, I'd like us to consider how bird populations respond to the environmental changes caused by fires. This varies widely across species, of course, but ecologists have discovered some

interesting patterns. For example, there's a paper that was published in 2005 titled Fire and Avian Ecology in North America, Process Influencing Pattern. This paper summarizes 10 other studies conducted in a variety of ecosystems across the continent. 203 bird species were included. The research here looked primarily at what happens in the first five years after a fire. According to this analysis, North American birds with certain traits prefer to live in recently burned areas. These fire-loving species increased in relative abundance in freshly scorched habitats, compared to nearby unburned habitats. Such birds included insect eaters that forage on either the ground, on tree bark, or in the air while swooping around. We're talking flycatchers,

swallows, woodpeckers, and wrens. Similarly, birds that nest in tree cavities, like chickadees, and those that nest on the ground tend to move into recently burned areas. There seem to be hundreds of published studies about how avian communities respond to wildfires. I guess you could say that this is a hot topic. When I say avian community here, I'm referring to the concept from the field of ecology. A community is a group of populations of different species that all live in the same place at the same time. You have plant communities, insect communities, bird communities, and so on. One example of a recent study is from 2018, and it has the title,

responses of birds to large-scale wildfires in Southern California. The researchers established 81 survey transects across the burns of three recent, enormous fires. The habitat in this case was mostly chaparral and oak woodland. Bird surveys were conducted for five years in burned and unburned areas and during two different seasons. The results of this study echoed what many other studies found. certain bird species do well after a fire, some are relatively unaffected, and others have a hard time of it. The authors of this study in Southern California grouped birds into three categories.

Fire followers, fire resilient species, and fire sensitive species. The most enthusiastic fire followers, the ones whose numbers increased the most after a fire, included Lajulai Bunting, Rock Wren, Costa's hummingbird, and black-chinned sparrow. The birds that declined most dramatically after a fire, the fire-sensitive species, included blue-gray natcatcher, mountain chickadee, cactus wren, and Hutton's Vireo. Populations of these species still hadn't fully recovered five years after the fires. Fire-sensitive species, whether in California, or in other parts of the world,

those birds don't do well in burned areas because some vital aspect of their habitat has been removed, maybe a food resource or suitable nest sites. For example, birds that eat mostly berries or fruit probably aren't going to find much food after a fire. The opposite is true for fire followers. These guys swoop in to find a wealth of opportunities in recent burns. For them, a fire opens up space in the habitat and clears away many predators.

There are abundant food resources and perhaps nest sites as well. You know, if birds were superstitious like humans, these fire-following species would probably worship wildfire as a god or something. Maybe they'd start a cult called the Followers of Fire, and they'd wear funny little hats to signify their devotion. All hail the glorious God of fire! May he incinerate our enemies and blacken the earth in his infinite benevolence. Other members of this cult in North America include species like the tree swallow,

mountain bluebird, western woodpewe, chestnut-sided warbler, and northern Bobwhite, which is a member of the New World Quail family, Odontaphoredi. Now, if you already know a thing or two about birds and fire, maybe you're thinking, But what about black-backed woodpeckers, Ivan? You forgot about them! Did I? Did I forget about black-packed woodpeckers? Actually, yes, I did, I forgot. So, thank you for the reminder. I'll make sure to talk about the black-backed woodpecker in a few minutes. But first, I want to acknowledge that even though the preponderance of scientific studies on fire and birds have focused on North American and Australian species, fire is also a big deal for birds in many other parts of the world.

Researchers have studied the relationship between birds and fire in places like Tanzania, Madagascar, France, and India. For example, on the island of Corsica in the Mediterranean Sea, one study found that coal tits and Corsican nut hatches swarmed into a recently burned pine forest. These seed-eating songbirds gorged themselves on the wealth of pine nuts. The heat of the fire had caused the pine cones to open up, creating a veritable cornecopia of nutritious seeds. Then there's the Indian roller, Carassius Bengalensis.

This is a gorgeous bird with pale blue, brown, and lilac-colored plumage. Indian rollers are drawn to active bushfires across the Indian subcontinent. They catch insects and other small animals on the ground as they scatter during a fire. In Sri Lanka, people call this bird Dumbana, which means the one who inhales smoke. Or more literally, it means smoke drinker. You know, I've known a few humans who are, quote unquote, smoke drinkers. They mostly just lays around in dimly lit rooms, smoking cigarettes and tossing back shots of bottom shelf whiskey. They tell rambling stories to anyone who might listen.

It's kind of sad, actually. So don't let that happen to you. Smoking is bad for you, kids. The Indian roller might be one who inhales smoke, but it smokes only because it has to. It's just an occupational hazard. I want to highlight a few well-studied North American bird species that depend on fire. One reason so many fire ecology studies focus on North America is because wildfires are common across the continent. Fire plays a vital role in many of our ecosystems, like ponderosa pine forest, jack pine forest, chaparral, oak woodlands, Midwest, Midwest prairie, and southern pine forest. So, not surprisingly, there's a large body of research on how fire plays out in these and other environments in America.

Okay, our first featured creature is a denizen of coniferous forests in the northern parts of North America. The black-backed woodpecker, Picoides Arcticus, is an extreme habitat specialist in burned forests. This bird is like the high priest of the followers of forest. fire cult. It's all black on its upper parts, and white underneath with heavy barring. The male has a patch of yellow on his crown. That jet black back gives the bird some excellent camouflage while it's foraging on the trunk of a charred tree. Black-backed woodpeckers move into burned forests in the first few months after a fire.

They nest in burns and reach their highest densities of breeding individuals there. But after two or three years, they pack up and leave. They head for greener pastures, or blacker forests, I guess. The camouflaged plumage of the black-backed woodpecker and its extreme attraction to charred forests are traits that probably evolved over millions of years. This supports the idea that wildfire has been an important feature of forests in North America for a very long time. So why do these woodpeckers love burned forests so much?

Maybe they're attracted to the aesthetic of the dark, post-apocalyptic scenery, like moody artistic teenagers who read Edgar Allan Poe stories and listen to Goth Rock. Actually, the woodpeckers probably aren't all that interested in the scenery. What they're after is bugs, specifically wood-boring beetles. These beetles and their juicy larvae infest dead and dying trees in recent burns. Healthy living trees defend themselves against beetle infestation by secreting sap and toxic chemicals. Without such defenses, trees can get overrun with beetles. Wildfires attract many wood-boring beetle species.

The insects home in on either the heat or the smoke. Hordes of beetles fly in after the fire. passes and they start laying their eggs in the wood. And hot on the heels of all those insects are the black-backed woodpeckers. The birds set up shop and start chowing down. Long-horned beetle larvae are one of their favorite snacks. Black-backed woodpeckers pound away on the wood of tree trunks to excavate beetle larvae. More so than most other woodpeckers, this species has several anatomical adaptations for delivering the most powerful blows as it forages. Blackbacks can therefore excavate grubs from relatively hard wood.

One of these adaptations for hard pecking is having only three toes. That's right, only three toes. Well, per foot, that is. Most other woodpecker species have four toes on each foot. Some researchers hypothesize that having only three toes allows for a stronger grip on the tree. Seems kind of counterintuitive to me, but I'm in no position to argue. I defer to the ornithologists who have been studying these birds. Here's the sound of a black-backed woodpecker whacking away on a tree, digging for beetle larvae while

gripping the trunk with its little three-toed feet. Black-backed woodpeckers excavate wood not only to find their next meal, but also to hollow out their nest cavities. A mated pair of woodpeckers makes a new cavity every time they nest. So they might end up creating multiple cavities in a single patch of burned forest. This is important because those cavities end up being used by other birds, like bluebirds, chickadees, and nut hatches. None of those little guys can excavate their own nest cavities. They depend on the woodpeckers. So black-backed woodpeckers change their environment in a way that benefits other members of the avian community. So that's Picoides Arcticus, the black-backed woodpecker,

a fire follower and highly specialized bird that thrives among the sooty ruins of burned coniferous forests. I've got another member of the family Piggadie for you. Maybe you recall from episode 11 of this podcast that Pickety is the Woodpecker family. This one is the red cockated woodpecker, Dryobadis Borealis. It lives in pine forests of the southeastern United States. The red cockated woodpecker is superficially similar to some other more common members of the genus Dryobaties, like the Downey Woodpecker. It's small with a black and white checkerboard or ladder pattern on its back.

Its white breast is sprinkled with black spots and it has distinctive white cheek patches. The word cockade is what we call a ribbon or other patch of colorful fabric worn on a hat. On the woodpecker, the cockade is only on the males. They have little slashes of red just above their white cheeks. The essential habitat for red cockated woodpeckers is old-growth pine forests with plenty of open space between the trunks of large trees. Unlike most other woodpeckers, these guys excavate their nests in the

the wood of live trees, in pines specifically. It takes a lot of work and a long time to carve out a nest in living wood. So these birds tend to occupy the same territory for a long time. What keeps the forest habitat open and savanna-like is, of course, fire. Under the natural fire regime, lightning-caused fires would sweep through the forest every one to five years. Mature pines could resist the flames, but many other trees would be killed off. This prevented deciduous trees like oaks from growing too tall and dense. Red cockated woodpeckers usually carve out their nest holes high on the trunk of a pine, well above the height that most fires reach. The birds also peck holes in the sap wood around the nest cavity entrance. Sap oozes out of the little holes and

encircles the cavity. This ring of sticky goo acts as a barrier to keep out predators like tree-climbing snakes. But, uh-oh, pine sap is highly flammable. So it's a good thing the woodpeckers place their nests up so high. Otherwise, they might come home to find their nest surrounded by a ring of fire. You know, just like the 1967 hit song by Johnny Cash. In fact, I'm pretty sure that's what Johnny was singing about, the hard life of being a red cockated woodpecker. You know, I fell into a burning ring of fire. I went down, down, and the flames went higher, all that. And life is hard for red cockated woodpeckers, because their special habitat is now exceedingly rare across the southeast. Over 80% of these forests

were mowed down for lumber by the middle of the 20th century. And then Smokey the Bear and his cronies kept putting out every fire they could find. Fire suppression like this allowed those oaks and other hardwood trees to fill in the empty spaces between the pines, ultimately crowding the forests. Habitat destruction and alteration have left only 3% of the forest that red-cockated woodpeckers need to survive. When the Endangered Species Act was made law in 1973, this bird was already on the list of endangered species. And it's still on the list today. The U.S. Fish and Wildlife Service heavily manages the remaining populations of red cockated woodpeckers, all of which are small. As I understand it, the two primary strategies used to preserve the

species are, one, creating artificial nests in pine trees, and two, using prescribed burns to maintain the natural structure of the forest. Now get this. Back in the 1990s, some private landowners didn't want to be forced to follow any woodpecker-related regulations imposed by the Fish and Wildlife Service. So what did these landowners do? They preemptively cut down hundreds of acres of forest on their properties. They wanted to prevent any woodpeckers from making their homes there. Wow, way to go, guys. Thankfully, hundreds of private landowners these days are working voluntarily with the Fish and Wildlife Service to protect the woodpeckers.

and these birds need all the help they can get. The red cockated woodpecker is what we call a conservation-reliant species. For the species to survive, it will need to be heavily managed by government agencies and conservation organizations, maybe forever. And fire? In the form of prescribed burns, fire will continue to be one of the best tools to help maintain the habitat of these little birds. The last North American bird I want to highlight today is also a conservation-reliant species. Kurtland's warbler, setafaga curtlandii, is in the family Perulidi.

I covered that family in episode 28 of the podcast, and I talked about Kurtland's Warbler in that episode. But I think it's worth telling you again about this fire-dependent bird. Kurtland's warbler is a rare bird that breeds in just a few places around the Great Lakes. It's a migratory species that spends the winter in the Caribbean. Males are handsome little dudes. They have dark gray upper parts and they're bright yellow underneath. Female Kurtland's warblers are similar, but they aren't quite as colorful. Like the red cockated woodpecker, Kurtland's warbler was one of the first birds put on the

endangered species list. But unlike the woodpecker, Kirtland's warbler is no longer on the list. The thing is, this warbler is very particular about its breeding habitat. It builds its nest on the ground in young jack pine forest, forest that's less than about 15 years old. When the forest matures beyond that point, the magic is gone and the warblers stop breeding there. Historically, wildfires regenerated patches of jack pine, continually creating breeding habitat for Kurtland's warbler. Throughout the 20th century, however, humans destroyed and altered jack pine forests to the point that the Kurtland's warbler population declined precipitously. Once again, we also have to blame Smokey the Bear. Over zealous fire suppression in jack pine

forests allowed more stands of trees to mature well beyond 15 years of age. Without wildfires to sort of reset the clock, Jack Pines just got older and older and the warblers lost more and more habitat. This is yet another example of humans and anthropomorphic shovel-wielding bears messing up the natural fire regime. While we're on the subject of Smokey the Bear, don't you think it's kind of weird that he wears blue jeans? He's got pants on and a hat, but no shirt.

Where's your shirt, Smokey? I could understand pants and a shirt, or I can understand wearing neither, but just pants. Also, I want to point out that this guy's ranger hat says smoky on it in big red letters. That's kind of weird. I mean, what do you think would happen if I went walking around in public, pointing at people and swinging a shovel, wearing only jeans and a hat with my name Ivan printed on it? I think I'd end up in the back of a police car with handcuffs on. But I digress.

Kurtland's Warbler. Once Kurtlund's Warbler was given legal protection under the Endangered Species Act, a lot of work went into saving it. You'd think that prescribed burns would be one of the management strategies. But instead of fire, habitat preservation is accomplished by large-scale timber harvesting. As patches of jack pine mature beyond 15 years, managers chop down the trees. In this case, logging mimics the disturbance that would normally be caused by fire. Hundreds of thousands of acres of this warbler's breeding habitat are maintained like this

in the states of Michigan and Wisconsin. Conservation efforts have paid off, and there are now at least 4,000 adult Kurtland's warblers breeding in the jack pine forests of the Midwest. That's up from a low point of only about 200 breeding pairs in the 1980s. In 2019, Kirtland's Warbler was officially removed from the endangered species list. But this is a conservation-reliant species, remember, it's not out of the woods yet. Kurtland's Warbler will continue to depend on the large-scale management of its habitat for the foreseeable future. Leaving North America behind, let's head down to the Southern Hemisphere,

to the continent of Australia. Wildfires are also integral features of many ecosystems there. Australians call them bushfires, but, you know, same difference. Eucalyptus forests in eastern Australia are particularly adapted to burning. Eucalyptus trees contain flammable oils in their leaves, and some species have shredding bark that makes great fuel. Many other Australian plants and animals are well adapted to living with bushfires. But living with fire is one thing.

Actually taking an active role in spreading fires? That shameful privilege is reserved only for us humans, right? Nope, not anymore. Amazingly, it turns out that there are at least a few raptor species in Australia that have learned how to spread fire. The pyromaniacs in question are the brown falcon, whistling kite, and black kite. A study on these three species was published in 2017 in the Journal of Ethno Biology.

The paper's title is Intentional Fire Spreading by Firehawk Raptors in Northern Australia. That's what people are calling these birds, quote-unquote, fire hawks. The researchers describe their own observations of brown falcons, whistling kites, and black kites in the tropical savannas of Australia. and they also document eyewitness reports from firefighters, rangers, and Aboriginal people across Australia. Here's what the birds do, in general. They gather at the edges of an active bushfire.

They swoop around picking off small animals fleeing from the flames. But every so often, one of these so-called firehawks will snatch up a smoldering stick in its beak or talons. It then flies out beyond the bushfire front, and drops the stick in some dry grass. And whoosh, a new fire flares up. And get this, sometimes these raptors work in groups to ignite fires by dropping multiple burning twigs.

These clever birds spread the fire intentionally to flush out more small animals to prey on. How crazy is that? The only other animal that uses fire as a tool like this is us, humans. Once again, we learn something about birds that is just mind-blowing. Now, so far, there don't appear to be any actual photos or videos that document this phenomenon, which is known as avian fire spreading. The lack of hard evidence makes me a little skeptical, but with all the reports and accounts,

it seems like it's legit. I imagine it's only a matter of time now before there are YouTube videos and BBC documentaries showing avian fire spreading. This reminds me of an experience I had in Uganda a few years ago. I was leading a tour, and we came across a bushfire not far from the Nile River. The smoky sky was full of abdim's storks, soaring in circles on the rising heat. The freshly scorched grassland around us was teeming with these large birds. They were striding around in the fields, foraging for insects that were fleeing the fire,

or that were already roasted. Abdim's stork is yet another bird that's attracted to fires, just like the smoke-drinking Indian roller I mentioned earlier. Maybe some bird species like these have also evolved the behavior of fire spreading. Who knows? If three species of Aussie raptors do it, it seems possible that we'll find a few other arsonist bird species out there, somewhere. Let's just hope that black-backed woodpeckers in North America

don't learn the fire-spreading trick. I can just see our little fire-following woodpeckers gleefully tossing flaming sticks on forest after forest, igniting blazes all over the place. The birds could create vast swathes of their own habitat. North America's expansive coniferous forests might go up in smoke, reduced to a black, ash-choked hellscape. Well, as the old saying goes,

one man's hell is another bird's heaven. A lot of what I've been talking about so far is how fire benefits birds. There are short-term benefits, like fire hawks and abdim storks getting an easy meal during an active fire. And there are all those long-term benefits, where wildfires create and maintain bird habitats. But fires can have plenty of downsides for birds, both short-term. term and long term. Sometimes Frankenstein's monster is right. Fire bad. Many bird species lack adaptations for living with fires. Recall that there are those fire sensitive species. I imagine a lot of the birds living in ecosystems where large wildfires are rare would fall in the

category of fire sensitive. The most obvious short-term threat of fire is direct mortality. Birds die when they can't escape a wildfire. But active fires can also hurt birds in less direct ways. Recent research has shown that thick smoke from large wildfires can cause big problems for birds during migration. A study of greater white-fronted geese in western North America found that these birds deviated far from their normal migration routes in September of 2020. At that time, dozens of enormous fires were burning in California, Oregon, and Washington. The geese were trying to get from their breeding range in Alaska down to California, where they spend the winter. Scientists tracked a handful of greater white-fronted geese using GPS collars.

The GPS data showed that in 2020, the birds took longer, more circuitous migration routes, and that they sometimes flew much higher than normal. Doing all that, they would have burned far more energy. This study makes a convincing case that these birds were most likely trying to escape the giant clouds of smoke in the atmosphere. Many other migrating bird species probably have been or will be affected negatively by smoke from large fires. The biggest long-term threat of wildfire, the one that's often the most glaring to us humans, is habitat destruction. For many birds, a burned landscape is a wasteland. For example, this might be true for countless forest-dwelling species that thrive where

there are plenty of leafy trees, shrubs, and other vegetation. In places where natural fire regimes still hold sway, we can assume that any habitat destruction from fire is just business as usual. It's temporary, just part of the circle of life. The bird populations in these places have been adapting to fire. for a long time, and they'll probably be okay. But what if wildfires became larger, more frequent, and more severe? What if the pattern of wildfire occurrence changed dramatically,

such that habitat destruction far outpaced habitat regeneration? Well, as I mentioned earlier, that's basically what's happening in some parts of the world. For example, it seems like every year or two we have to use the word unprecedented to describe the gigantic fires that erupt in California and elsewhere in the western U.S. Things are getting worse and worse here. In the last four decades, the average extent of forest burned in the United States each year

has gone up by 1,000 percent. And the fire season is now several months longer than it used to be. Mega fire has become a household word. A megafire is one that burns more than 100,000 acres, or about 41,000 hectares. Megafires have made the news in California again and again in recent years. And then there were the fires that burned 25.5 million acres across Australia in late 2019 and early 2020. Later in 2020, devastating fires scorched 4.5 million acres in Brazil's Pontinal ecosystem, which is the world's largest tropical wetland. These examples represent fires that probably

torched far more habitat than we would expect under historical fire regimes. This is bad news for birds and other wildlife. Not only were billions of animals killed by these fires, there may also be long-term population declines due to habitat destruction. If fires like these continue to become more frequent in the coming decades, birds may not have time to adapt. There are several reasons large catastrophic wildfires are happening more often. First, a long history of fire suppression in the U.S., Australia, and elsewhere created unnatural conditions where forests grew dense and choked with flammable brush. Second, people continue to build homes and communities in or at the edges of fire-prone ecosystems.

More people means more opportunities for fires to start, whether accidentally or intentionally. But the biggest reason fires are getting worse is climate change. Human-caused climate change has, in many places, raised average temperatures and resulted in severe droughts. Prolonged drought, combined with low humidity and wind, creates the perfect conditions for megafires. Droughts set the stage for all those terrible fires in California, Australia, and Brazil. Like anything that has such important consequences for people and wildlife, the relationship between climate change and wildfire is a subject of debate among scientists. But the debate is mostly about the finer details.

It seems the general consensus is that climate change is indeed the underlying reason for the growing threat of fire. Well, all that gloom and doom was fun to talk about, wasn't it? You know I like to inject a bit of silly humor into the show, but some subjects just need to be addressed in a more solemn tone. So it goes, right? How about we return to the Chiricawa Mountains of southeastern Arizona? soon after that megafire in 2011 burned pretty much the entire mountain range ecologists got to work studying its long-term effects on the ecosystem

to figure out how bird populations would respond to the fire biologists from the Rocky Mountain Research Station partnered with local birders enlisting their help as citizen scientists interestingly the three-year study found that after the fire bird species diversity increased across the entire mountain range. The explanation is that in the wake of the big fire, there was a more diverse mosaic of habitat types available for birds. The lead researcher, Jamie Sanderlin, said,

quote, As with most wildfires, there was a range of fire severities, where some areas burned pretty hot, some more moderately, and then some had very low to no fire. end quote. So the overall number of bird species in the mountain range increased. But you shouldn't be surprised to hear that not all species responded in the same way to the fire. For example, ash-throated flycatcher, western woodpewee, and buff-breasted flycatcher were among the species that responded positively.

These guys prefer more open habitats. Other species like Grace's Warbler require more mature, closed forest habitat. Species like this responded negatively to the fire. For people who live in the Chiricahua Mountains, and for those of us who love to visit the area, the 2011 fire felt like a disaster. It was awful. The tall forests that I came to love when I explored the Chirikawa's in 1999 won't grow back in my lifetime. But taking a longer perspective, beyond a single human lifetime, we might discover that the ecosystem is resilient to fires like this. After all, preliminary data suggests that the birds are doing okay. And other research on historical fire regimes in Arizona suggests that what happened in 2011 may be within the

natural range of wildfire severity. So maybe this was simply a case of fire doing what it has done for millions of years. A case of fire renewing and reshaping an ecosystem in a way that increases biodiversity, including the diversity of birds. I hope you found this episode interesting. I think fire ecology is just fascinating. And for better or for worse, it's becoming more relevant these days. Thank you so much for listening and for taking some of your value time to learn about birds. I hope you can share some of what you learned today with your friends, your family, maybe random strangers in public bathrooms, anyone, really.

The Science of Birds is supported by my awesome patrons on Patreon. These are enthusiastic fans of the podcast who chip in to help me to keep creating content for you. My newest patrons are Gail Gramerosa, Timothy Daly Valdez, Chico Rie. Rivera, Nuala Morais, Gen Grovat, and Natalie Friendberg. A big thank you to each of you for your generous support. You guys are just too cool. If you, my friend, are thinking you might like to support my work,

check out my Patreon page at patreon.com forward slash science of birds. You can reach me by email if you have something you'd like to share. The address is Ivan at Scienceof Birds.com. drop me a message. You can let me know what you think of the show, or maybe you want to tell me about that one time when you fell into a burning ring of fire. The show notes for this episode,

which is number 40, can be found on my website, scienceofbirds.com. This is Ivan Philipson, and I'll catch you later. Cheers.