8 September 2021
Fear causes an inability to thrive in humans. Now a new study shows this is true of birds as well.
As a grad student at University of Massachusetts in Amherst, Aaron Grade decided to parse out why urban nestlings are lower weight than their rural cousins. It’s well known that urban settings have poor habitat, altered food sources and more predators but the likelihood of predation is lower there because urban predators have so many other food choices.
Grade wondered if fear play a role so he set out 38 house wren nest boxes and loudspeakers in participants’ backyards in urban, suburban and rural western Massachusetts. During the nesting season participants played back the sounds of two predators of house wrens: Cooper’s hawks (pictured at top) and eastern screech-owls (below).
Though there was no actual danger, parent house wrens responded to the sounds by guarding their young and perhaps feeding them less. In the end nestlings in these playback settings were 10% underweight no matter what habitat they grew up in.
The study found that whether the birds are hurt or not, their nestlings are underweight and less likely to survive if the family lives in fear.
“These landscapes of fear,” says Grade, “can have a greater effect on behavior and survival than the actual predator itself.”
— Science Daily: How landscapes of fear affect the songbirds in our backyards
Birds and humans cannot thrive in constant fear.
Read more about the birds at Science Daily.
Read about humans at Low Birth Weight Babies and Black Women: What’s the Connection?
(photos by Dave Brooke, Wikimedia Commons and Bobby Greene)
p.s. This is also a lesson for birders: Avoid using playback of predator sounds, especially during the spring and summer nesting season!
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