Five Species That Thrive Alongside Fire, From Lilies and Beetles to Woodpeckers, Hawks and Grass

The first species is the fire lily, Cyrtanthus ventricosus, found in the fynbos shrublands of southern Africa. Its striking orange-red color gives the flower its name, but Dickson explains that it appears only after a fire. Wildfires are common in this environment, and many local plants recover well from them, but fire lilies rely on fire rather than merely surviving it.

The bulbs sit dormant in the soil until conditions are right. Dickson says they may remain dormant for over a decade, and only after a wildfire scorches the land above them will they grow, emerging from the ash "like a baby phoenix." Once they start, growth is fast: the flowers go from bulb to full bloom in just seven to nine days. The hollow stem helps make this rapid growth possible because it is sturdy yet light on structural material. A grove of fire lilies therefore signals that a fire came through about a week earlier, and the surrounding landscape would be full of burned and dead plants.

The benefits are clear. With other plants destroyed, the fire lilies have unimpeded access to sunlight and soil nutrients. A field of bright flowers against ash is also easy for birds and butterflies to see, and those animals are essential for the flowers' reproduction. What triggers the bulbs is less certain. Many scientists suspect ethylene gas, which plants use to regulate growth and development, but studies have found conflicting evidence. The bulbs may also react to heat or light from the fire, or to a combination of these factors. People have tried to cultivate fire lilies because of their beauty and hardiness, but they have had little success.

In North America, wildfires are not usually followed by fire lily blooms but are often accompanied by swarms of fire beetles. Most insects are flammable and flee the heat or smoke of a fire, but beetles of the species Melanophila acuminata fly toward the flames. Because the behavior is common and the beetles are widespread, a wildfire almost anywhere across the Northern Hemisphere has a good chance of attracting them.

Dickson says the beetles are not seeking a fiery death but a mate. Wildfires serve as meeting places where the beetles gather, find partners, and mate in the glow of the firelight. The flames make the meeting spot easy to find and keep away many predators and competitors that avoid fire. After mating and once the fire dies down, the females lay eggs in the freshly burned bark of trees and shrubs. When the eggs hatch, the grubs feed on the weakened plant tissue and on fungi growing on the dead wood.

Fire also speeds up the beetles' development. Normally, it takes about a year to go from newly laid eggs to fully developed, pupating larvae. Dickson cites one study reporting that beetles developing in recently burned wood could grow up in just two months.

The beetles have sensors suited to this lifestyle. Small pits on the underside of the thorax are extra sensitive to heat, which may help them zero in on a fire and monitor changes in fire behavior while they search for mates and lay eggs, so they are not caught by a sudden flare-up. Dickson also suggests they detect smoke with their antennae and scout flames with their eyes, allowing them to travel many miles to gather at a fire. Their attraction is strong enough that they have been known to swarm lumber yards, smelting plants and burning buildings, where their loud buzzing and painful bites can bother evacuees and firefighters. A report from the 1940s describes swarms hanging around University of California, Berkeley football games, possibly drawn by cigarette smoke from the crowd.

Some species are attuned to these conditions. North American black-backed woodpeckers range across the northern parts of the continent, but they live almost exclusively in areas that recently experienced severe fires. One study in the northwestern United States counted almost 200 sightings of these woodpeckers, and all but six were in burned forests. Dickson says the birds do not just like burned forests; they specialize in living there.

Like the fire beetles, the woodpeckers probably benefit from the general lack of predators and competition after a forest fire. The relationship is also a food chain: the bugs feed on dead plants, and the woodpeckers feed on the bugs. Because of the beetles' reproduction, the wood of burned trees is full of grubs, and woodpeckers are experts at extracting bugs from bark.

As scientists study these environments, it is becoming clear that burned habitats support unique and complex ecosystems of their own. Dickson calls this valuable knowledge for conservation and wildlife management. He summarizes the point simply: it is easy to think of a burned forest as a destroyed habitat, but in reality it is just a different one.

Naturalists have long noticed that wildfires are especially good places to spot predatory birds. In Oklahoma, one study observed bird activity during 25 fires in 2013 and 2014. It found that Swainson's Hawks seemed to like hanging around the fires, and at times they could be seven times more abundant during fires than before and after them. The birds were not just enjoying the heat; they were hunting. While prey animals ran from the flames, the hawks snatched up rodents and lizards that had been flushed out or injured by the fire. The study called this behavior pyric carnivory, meaning actively hunting around fire.

Swainson's Hawks are not the only ones. The same study noted red-tailed hawks and Mississippi kites gathering to hunt near the fire, and Dickson says other species around the world have shown similar behavior. Storks and buzzards have been known to follow fires and pick off dead or injured prey the blaze leaves behind. For these predators, a fire can save much of the time and effort otherwise spent seeking and chasing prey.

Dickson adds that some birds have been reported to intentionally spread fires. All across northern Australia, there have long been reports of kites and falcons flying into active fires, picking up burning sticks, and dropping them somewhere else. This spreads the flames and flushes out even more prey. However, Dickson notes that no scientific study has directly documented this fire-spreading activity, so the details remain unclear. The behavior is widely known to Indigenous communities in the region, and people who manage brush fires are often wary of birds that might carry flames to new areas.

The last entry on the list is grass. Many grasses live modest lives in small patches on forest floors or in cracks in sidewalks, but some form massive grasslands that stretch to the horizon, and these are among the most extensive biomes on the planet. Dickson says these grasslands exist because of fire. Without fire, the world would have much less grass and many more trees.

Grasses are just as flammable as other plants, but they grow very quickly and can bounce back right after a fire. Trees are slower to rebound. Grasslands are therefore especially successful in fire-prone regions, particularly in parts of Africa and South America. With such regular fires, forests do not get the chance to grow, and grasslands take over. The reverse also holds: where humans have suppressed natural fires, grasslands are gradually replaced by forests. Dickson says this relationship between fire and vegetation is thought to be a major reason the Earth is so grassy.

Dickson says grasslands are a relatively young feature of the planet. Fossil evidence shows they began spreading widely only about eight million years ago. At the same time, the fossil record shows a significant increase in burned plant remains. Dickson links this shift to the onset of monsoon-style climate patterns, which created habitats with distinct wet and dry seasons. Plants grow profusely in the wet season, and when they dry out or die in the dry season, they create fuel that clears space for growth in the next wet season. As this climate pattern became more common, ancient forests were replaced by grasslands.

Dickson describes a 2004 study that ran a simulation modeling vegetation growth, climate conditions and fire regimes around the world. When the model reproduced modern conditions, it predicted grasslands and forests roughly where they exist today. When fire was removed from the equation, more than half of the world's grasslands were overtaken by forest. Without fire, the planet would have much less grassland, and fewer species that evolved to live there, including large herbivores such as horses and bison and their predators such as lions and wolves.

Dickson notes that many of the grasslands that disappeared in the fire-off simulations were in Africa. The spread of those grasslands in particular is thought to have been a major factor encouraging our ancestors to move out of the forests and into more open, grassy habitats. Dickson concludes that long before humans learned to wield fire themselves, fire played a crucial role in setting the stage for the evolution of our own species.