University of Florida Institute of Food and Agricultural
Sciences
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| Tufted Titmouse. Photo by Will Collette |
New research from University of Florida Institute of Food and
Agricultural Sciences researchers shows birds may be avoiding habitats near
noisy highways because they can't hear fellow birds' alarms that warn them of
attacking hawks or owls.
Some highways cut through or run along natural areas, and
researchers know that wild birds often make their homes away from those
highways, but they don't know why.
UF/IFAS researchers tested whether highway noise could be
interfering with bird communication.
Results of their study suggest too much
noise around these highways keeps birds from hearing warnings from fellow birds
about predators in the area, and that puts them at a higher risk of being
eaten.
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| Chipmunk didn't hear the warning. Photo by Will Collette |
The researchers caution that they did not establish a causal
link between highway noise and bird population reductions, although
noise-disrupting alarm calls is a compelling possibility.
"Conservation of bird species should include decreasing
noise in sensitive wildlife areas," said Aaron Grade, who led the study as
part of his master's thesis in the UF/IFAS wildlife ecology and conservation
department.
Grade and his graduate adviser, UF/IFAS wildlife ecology and
conservation professor Katie Sieving, tested the abilities of northern
cardinals to hear the predator alarm of tufted titmice by playing alarm calls
to cardinals through speakers in both noisy and quiet locations in Florida
state parks. They found that noise from vehicles along the busy highways often
drowns out the alarms emitted by birds.
Researchers went to Florida state
forests near Interstate 75 and U.S. 441 in Alachua, Marion and Columbia
counties to test whether highway noise could interfere with bird communication.
Northern cardinals and tufted titmice are two abundant bird
species in the woods of eastern North America. Many bird and mammal species
rely on information from tufted titmice calls to detect and respond to
dangerous predators.
This causes important information networks to form around
tufted titmouse communication. Normally, northern cardinals listen to tufted
titmouse predator alarm calls and will typically respond by fleeing or freezing
until the danger passes.
But when tested near noisy roads, cardinals failed to respond to
titmouse alarm calls, suggesting that the noise may prevent cardinals from
escaping when there are dangerous predators around, Sieving said.
"Our work suggests that disruption of animal communication
networks could hinder natural behaviors of wildlife and help explain patterns
of reduced biodiversity near roadways," said Grade, now a doctoral student
at the University of Massachusetts.
The study was published online in April in the journal Biology
Letters.
