Years ago, Yellow-billed Cuckoos like this one were frequent visitors to the Pacific Northwest. They’re one of the few birds that eat tent caterpillars, a species that can wreak havoc on the leaves of trees. It’s a mystery why the cuckoos no longer come. During a tent caterpillar outbreak, we know it can’t be for lack of food. Something else must be at play.
Where Are the Yellow-billed Cuckoos?
Written by Chris Peterson
This is BirdNote!
[Car returns home]
It’s early June and I’ve been away. I arrive home to find our alder trees completely stripped of leaves. Standing quietly, I hear what sounds like a hundred thousand mouths chewing [insects chewing]. The walls of our house are covered with tent caterpillars.
Now it happens that one night late last July, we’d opened the windows. Within minutes, we heard this...
[Tent caterpillar moths against the screens]
Hundreds of small brown moths, Malacosoma californicum, were bumping against the screens. [Return to sound of moths]
We had no idea what lay ahead.
Female tent caterpillar moths live only a few days. They lay their eggs on trunks and branches of deciduous trees then cover the clusters with a frothy little mass that hardens like Styrofoam. This allows the eggs to overwinter. In spring, the larvae emerge as caterpillars, spin a silk “tent” and eat young leaves. After eight weeks as caterpillars they form cocoons. In another two, they become moths. The moths reproduce, and the cycle begins anew.
Years ago, Yellow-billed Cuckoos were frequent visitors to the Pacific Northwest. [Call of Yellow-billed Cuckoo]. Yellow-billed Cuckoos -- one of the few birds that eat tent caterpillars. It’s a mystery why they no longer come. At least this year, it can’t be for lack of food. Something else must be at play.
[For BirdNote, I’m Mary McCann.]
Call of the Yellow-billed Cuckoo  provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York and recorded by Terri Gallion.
Ambient birdsong recorded by C. Peterson Marantz III T 47 and moths on screens Marantz II 144
BirdNote’s theme music was composed and played by Nancy Rumbel and John Kessler.
Producer: John Kessler
Executive Producer: Chris Peterson
© 2013 Tune In to Nature.org June 2013 Narrator: Mary McCann