A new Washington State University study finds one species of songbird was so impacted by wildfire that it delayed the period where the males molted into bright plumage, thus postponing the breeding season.
The discovery was made in Australia by WSU researcher Jordan Boersma after a wildfire raced through the habitat of the red-backed fairywren.
About 50 of the birds took shelter in a donkey paddock and soon Boersma noticed something unusual was happening with the male birds.
“This is the time of year where normally they would be molting into this showy red and black plumage, and a lot of them just weren't doing that," he said.
The bright plumage attracts female birds during the mating season. But following the fire, the grassland where the birds would normally nest was wiped out.
Testing revealed that the male bird's testosterone had been reduced, which in turn inhibited their normal change to bright plumage. Boersma says he believes it was an internal defense mechanism at work.
“The birds are able to perceive a change in their environment and respond to fire by putting these mechanisms in place that will keep them from producing traits that might be costly. These showy feather colors are going to attract unwanted attention from predators. It could get them into fights that there's no reason to be in, and there's no point in being in a fight over a breeding territory if you can't breed," he said.
One twist was that during the previous season, the region suffered from a drought, yet the birds still underwent their bright plumage change.
Boersma theorizes in that case, the birds were ready for the normal monsoon season, which eventually arrived, bringing with it a large number of insects the birds would feed on.
“Because then you're ready if a rain comes to compete for mating opportunities and make a nest. But when a wildfire comes through and destroys the nesting substrate, even if the rain comes, you still have to wait for the grass to grow up to a level to where you can nest," he said.
Boersma believes the study provides evidence that observing the plumage colors of birds can provide evidence of how healthy their environment is. If it appears there are very few males undergoing the transition, that's a good clue something in the environment is amiss.