PULLMAN (Wash.) - Fire can make a tropical songbird's sex lives ice.Researchers discovered that male red-backed fairywrens were less likely to mate after the destruction of their habitat in Australia. Their showy feathers were also associated with a lower circulating testosterone.The Journal of Avian Biology published the results of the research. They also measured the fat stores of the birds and corticosterone, but they found that these levels remained normal.Jordan Boersma (Washington State University doctoral student) said, "Really it all came down to testosterone." He was also the lead author of the study. There is no evidence that birds were stressed. Wildfire was simply interfering in their normal temporal pattern for elevating testosterone and producing the colorful plumage.Boersma said that although the findings are unique to the tropical songbird, they could have implications for other species with special coloring for mating.He said, "It could help you gauge the health of a population if it is known their normal level ornamentation." If you notice that very few males are going through this transition, it means that their environment is not ideal.Male red-backed fairywrens that aren't boosted with testosterone won't be as red. They have brown, drab feathers that look just like their female counterparts. They can be distinguished from predators and provoke conflict with males by having ornamental feathers. Boersma says that flashy feathers can be "expensive." They only attract female fairywrens.Boersma stated that the females will mate with a handsome male fairywren. They use a variety of mechanisms to obtain their ornamentation, including testosterone.Boersma and colleagues previously found that testosterone aids fairywrens to produce their vibrant feathers by converting pigments from their diet, called carotenoids. The birds' reaction to wildfire is further supported by this study.Although other studies have looked at the effects of wildfire on long-term survival of animals and birds, this study is the only one that examines how wildfire might affect birds' physiology.Researchers believe that red-backed fairywrens have evolved to live with wildfires. Wildfires can cause damage to grassland nesting habitats, which could indicate that it's not a good time for the birds to raise their young. By remaining unattractive to their mates, the male birds can hinder or delay reproduction.The researchers collected blood samples from fairywrens at two locations in Queensland's tropical northeast for the study. This allowed them compare wildfire-prone birds with others.Red-backed fairywrens are males that wait until the monsoon season for their bright colors to change. The rains bring more insects into the open, so they wait to molt. Researchers wanted to make sure that it wasn't dry season, but wildfire, that was affecting the birds' testosterone levels and their feather color. The study period was unusually dry. Researchers observed very little breeding, but males still produced ornamentation at a normal rate. Only after the fire, the majority of male birds became brown.Researchers found that males were more likely to remain brown after a wildfire, and that testosterone levels in brown males were lower than in other years.###
