The 2018 fire season’s explosive Carr and Mendocino Complex (California) conflagrations – among many others – illustrate the damage wildfires do to human infrastructure as well as fire’s effects on birds, other animals, and their habitat. This article is third in a natural-disaster series that’s already looked at the effects on birds from earthquakes and from volcanic eruptions.
Both short- and long-term effects must be considered. In the short term, somewhat surprisingly, studies show that immediate avian mortality in wildfires is normally low. Stills and video of this season’s fires make it hard to imagine any possibility of escape, but birds can outfly even these flames.
When significant mortality occurs, it’s almost always due to smoke inhalation in thick smoke that obscures vision and renders escape more problematic. Birds’ airways are damaged by smoke in the same ways humans’ are; severe or prolonged exposure can cause death, and birds who recover from lesser exposures can still end up with chronic breathing problems.
Nonetheless, most birds survive the immediate fire. But when a fire burns 350,000 acres (nearly 1,000 square miles!) in a matter of days, as the Mendocino Complex fire has done, what becomes of the habitat and the birds that relied on it for food and shelter?
Here we discover an interesting difference between the effects of massive eruptions and huge wildfires. Such eruptions create a central “kill radius” inside which essentially nothing survives. Even intense wildfires, by contrast, “hopscotch” and leave numerous untouched pockets of vegetation where recolonization can begin almost immediately.
Even the burned out sections can support returning bird life relatively early on. Again unlike eruptions with their all-devouring surges of incandescent ash, wildfires leave behind partially carbonized branches and trunks. Those rapidly become both food source and ”condo complex” for wood-boring beetles and their larvae. These delectable grubs attract woodpeckers in particular. The new clearings created in the burned-over areas become swarming grounds for all sorts of aerial bugs – and feeding grounds for flycatchers, bluebirds and the like. Birds that nest in clearings but feed in the surrounding untouched patches also find new homes with little ado.
Birds themselves play a significant part in the land’s re-greening after wildfires. They eat seed-containing berries and fruits, and in the process of digesting the tasty part, their acidic juices weaken the seed coats and facilitate easier germination. The birds fly hither and thither, excreting as they go, thereby assuring a wide distribution of now-ready-to-sprout seeds complete with a starting dose of guano fertilizer.
Another aspect of wildfires is their natural place in the ecosystem. We now understand how fire plays a key part in germination of seeds in species such as lodgepole pines, jack pines, banksia and eucalyptus. In some species heat is necessary to melt the resinous coating surrounding their seeds; in others, remarkably, chemical “indicators” in the smoke itself will trigger the seeds’ germination process. This allows repopulation by the original flora. The endangered Kirtland’s warbler, as one example, benefits from this cycle: It feeds only on young jack pines that sprout from the ashes of their parent trees.
Until recent years forest managers didn’t recognize the importance of regular, smaller fires that thin the undergrowth and burn accumulating deadwood. Our Forest Service worked hard for decades to suppress any and all fires; the result has been fewer, but more intense and damaging blazes that destroy these seeds rather than triggering germination. And on the front doorstep of climate change, even the “fewer” term in that equation is now called into question.
Proper forest management is a key to restoring and preserving the equilibrium that we ourselves tipped into imbalance. In doing this, we also help to assure the longer-term stability of that ecosystem as well as its bird and other animal populations.
Prairies too, like temperate and boreal forests, rely on fire to consume weeds, shrubs and dry brush, allowing native prairie flora more “elbowroom” and access to light. Birds such as the lesser prairie chicken and the horned lark thrive on recently-burned prairie.
Fire in a tropical forest is a different matter. The soil in most such forests is relatively thin and rainfall tends to be high. Exposing this soil to the elements as the result of fire often causes it to wash away and erode, or in other cases “laterize” (turn quickly to hardpan). In either case the forest will regenerate poorly, the habitat will be sparse and food will be scarce. Too many of these fires are started by humans eager to clear land for grazing or agriculture and failing to recognize the irreversible damage they’re setting in motion. To boot, the same natural processes quickly render the newly cleared land unsuitable for man’s intended use.
Many species of tropical-forest-dwelling birds have already had their numbers depleted by loss of habitat and, in species such as psittacines popular with bird fanciers, by excessive wild harvesting (or outright poaching, in many cases). An ever-diminishing range exerts severe pressure on populations. The additional insult of a tropical forest fire and its aftermath can force such species to the brink of extinction.
A discussion of birds and wildfires would be remiss not to mention the issue of whether several Australian raptor species (locally and colloquially called “firehawk raptors”) actually take advantage of fires deliberately to secure prey. The black kite (Milvus migrans), whistling kite (Haliastur sphenurus), and brown falcon (Falco berigora) have all been fingered as suspected arsonists.
No, they don’t rub branches together or strike steel to flint. They accomplish this by congregating at an existing fire, seizing burning branches in their beaks, carrying them for up to a kilometer and dropping them into unburned areas to spread the flames. The resulting blaze drives rodents and other prey ahead of it, allowing the waiting raptors to pick them off easily.
This behavior has been observed in flocks of more than a hundred, and researchers believe the birds’ strategy is intentional and directed. “It’s not gratuitous,” Australian ethnobiologist and ornithologist Bob Gosford says. “There’s a purpose. There’s an intent to say, okay, there are several hundred of us there, we can all get a meal.”
But though Aboriginal oral history abounds with tales of these firebirds, and more than a dozen modern-day sightings of this behavior are recorded, skeptics still point to a lack of photographic evidence. And even were such evidence forthcoming, the question of intentionality will continue to be debated hotly.
To sum up, birds affected by wildfires will suffer significant short-term disruption typically followed by recolonization, quickly in some areas and more slowly in others. The existing equilibrium is knocked off balance and “oscillates” for a time, with old species declining or being supplanted by new immigrants, followed by a gradual return to near steady state.
Birds themselves play a part in the regrowth of burned areas by bringing insect infestation under control and by spreading seeds already encased in natural “fertilizer”.
And there are those controversial accounts of a handful of Promethean raptor species snatching up blazing brands and firebombing the outback — using fire as a tool to roust prey and drive it towards their drooling beaks.
While individual species may not fare well in some instances, birds overall continue to demonstrate their resilience to wildfires much as they do to other large-scale natural events that humans call “catastrophes”. Indeed, some may even make good advantage of them.