Rim Fire.
Photo by Steve Ryan

You have (I hope!) seen news lately about the Rim Fire, which has been burning in Stanislaus National Forest next to Yosemite National Park. It began near the “Rim of the World” scenic viewpoint off Highway 120, and has been making Yosemite visitors and residents of Groveland quite nervous. It has burned over 200,000 acres and is reportedly 32% contained. A collection of pretty incredible photos of the fire is here.

First: no, this year’s juncos are not currently on fire. My field sites this year are in Stanislaus National Forest, but considerably further north. We have, however, seen smoke and had bits of white ash falling around us.

But of course, even if my juncos aren’t in the fire, other juncos are. And Chipping Sparrows, and American Robins, and mice, and gopher snakes… So what does wildlife do when the world starts burning around it? Are all the animals in that 200,000+ acres doomed?

Probably not, although the evidence is patchy and contradictory—and understandably so, since it’s largely based on people watching animals at a fire’s edge (hard to do), or searching burned areas for bodies afterwards. And fires are not all created equal: they may be more or less intense, faster or slower in advancing, smaller or larger, patchy or complete in their destruction. They may happen in a landscape replete with refuges or one with no escape. All of that variation probably affects what happens to the animals.

Photo by the Oregon Bureau of Land Management

Most of the evidence suggests that animals can handle fire just fine. Birds, larger mammals, and snakes move away from fire. Frogs are safe if they can get to water. The animal you might most expect to be in big trouble, the turtle, has been frequently found in perfect health immediately after burns: they hide in burrows underground. Smaller mammals may move or hide in burrows.

Most estimates of natural fire mortality have been low: healthy adult animals seem to be pretty safe. All of a population of adult Ruffed Grouse survived a burn, although their nests did not; a population of raccoons simply moved away with no fatalities; in a population of eastern diamondback rattlesnakes, the only mortalities were individuals in the midst of shedding their skin, which may have impaired their ability to sense or escape from the fire.

Two rather cruel experiments from the 1960s, in which small mammals in cages were placed in burrows or sheltered areas on land which was then burned, nevertheless had high survival rates. About half of the animals on land survived; presumably if they had been free to react, many more would have lived. Those in burrows lived if the burrow had more than one entrance for ventilation. Burrowing appears to be a highly effective strategy: one study found that animals could safely wait out a surface temperature of 1000 degrees F if they burrowed just 4 inches underground.

Some animals, disoriented by an unfamiliar danger and reluctant to leave a known safe place, have been seen getting themselves into trouble. A few fleeing cotton rats ran back into flames; some wood rats froze as a fear response until the fire overtook them, while others ran back to their on-fire homes. But these unfortunates were in the minority. Most of the cotton and wood rats escaped, some even carrying babies with them.

Cotton rat.
Photo by Jerry Oldenettel

The consensus appears to be that fire danger is fairly low—but variable. While the wood and cotton rats mentioned above had low-but-nonzero mortality rates, another population of cotton rats in another fire had 100% survival (woo!)—and another population of wood rats perished completely. Many reports suggest that birds are safe, but at least one found the bodies of small birds dead after a chaparral fire. Large mammals, usually fine, are sometimes killed by grass or chaparral fires.

Vogl’s (1973) description of a fire in a Florida wetland evokes the surreal juxtaposition of the deadly force of fire with the wildlife’s generally-unimpressed reactions. The fire was “broad and rapidly moving… with 2 to 4 m high flames… at least two fire whirlwinds… The fire crowned in the shrub growth and climbed up hanging Spanish moss…to several tree canopies.” Grasshoppers and damselflies fled as the fire approached. “Three cardinals flew from shrub to shrub as the fire burned around them and reluctantly retreated to the trees… Two white-throated sparrows fed on the ground until the advancing flames approached within 1 m of them, then casually retreated a short distance… The birds perched in the blackened shrubs… occasionally alighting in the smoking stubble before returning to their perches.

“During the 1st hour after the fire, two common crows landed in the smoke shrouded trees… In late afternoon, numerous spring peeper frogs (Hyla crucifer) set up a chorus in the wet portions of the burn even though the water was covered with ash. The following morning thousands of wolf spiders (Lycosidae) were crawling over the remaining grass stubble…”

Spring peeper, peeping.
Photo by Dave Huth

Here’s hoping the Rim Fire flames give way to smoking rubble, calling frogs, and wolf spiders soon.

References:

Bendell JF. 2012. “Effects of fire on birds and mammals.” In: Fire and Ecosystems, Kozlowski TT, ed. Science.

Russell KR, van Lear DH, Guynn DC Jr. Prescribed fire effects on herpetofauna: review and management implications. Wildlife Society Bulletin 27(2):374-384.

Vogl RJ. 1973. Effects of fire on the plants and animals of a Florida wetland. American Midland Naturalist 89(2):334-347.