According to surveys by scientists and avid bird-watchers, many songbird species are declining in the U.S. Losing the birds that provide a natural soundtrack in our backyards is a critical environmental issue, since they also serve to control insect populations and as pollinators.
Some scientists are examining the threats that songbirds face in the early stages of life to understand the decline. A study released Thursday in The Condor: Ornithological Applications by researchers at the University of Missouri-Columbia and the U.S. Forest Service suggests that the type of habitat songbirds choose after leaving the nest plays a large role in survival.
There's very little research that has looked closely at young songbirds that have just left the nest. Avian ecologist Julianna Jenkins at Mizzou said that's because the birds are challenging to study at that age.
"This period is really hard to study because these birds are very quiet and secretive," said Jenkins. "Once they leave the nest, they're hard to follow unless you put a radio transmitter on them."
Thanks to recent advances in technology, there are radio transmitters small enough to strap to small birds. Jenkins placed the devices in tiny backpacks worn by two species of birds that live in central Missouri forests - the Ovenbird and the Acadian flycatcher - and tracked them for four weeks.
Researchers found that most of the deaths occurred in the first week the birds departed from the nest. In addition, only half of the Ovenbirds that were tracked survived, versus 90 percent of the Acadian flycatchers. While the two birds share similar habitat, they make different choices for nesting and foraging.
Jenkins hypothesized that birds that chose to seek food in shrubby areas that would cloak them from predators would be more likely to survive. Unexpectedly, they found that birds that chose more open areas in the forest had better chances of living. Knowing this, said Jenkins, is helpful for conservation.
"We can alter habitat so the birds will do better," she said. "If we can find the right mixture of habitat for nesting and the post-fledging period, hopefully we can do something to boost survival."
Jenkins and other scientists are continuing to study the link between habitat and songbird survival. She hopes to answer questions, such as how a protected forest affects songbirds compared to a forest that has been disturbed by humans who are harvesting timber.