Cuckoos and Caterpillars

Many of you have probably noticed that we are experiencing a serious outbreak of Gypsy Moth caterpillars this summer. While seeing the leaves being stripped off many species of trees is disconcerting, there are some compensations.

Black-billed and Yellow-billed Cuckoos specialize in eating fuzzy caterpillars and they will move around to regions where their favorite food is plentiful. So, when we have high populations of either species of tent caterpillar or Gypsy Moth caterpillars these two nomadic species often appear in higher than usual numbers. Yellow-billed Cuckoos, in particular, may be difficult to find in “non-caterpillar” years.

This year, I have seen many Black-billed Cuckoos, often flying across the road when driving. I’ve heard both species at our place but a Yellow-billed seems to have settled on territory on our property. Unfortunately, he doesn’t seem to be making a noticeable dent in the caterpillar population yet.

Black-billed usually calls in series of 2-4 notes: cu-cu…cu-cu-cu… for example. Yellow-billed often produce a long series of single cowp notes. They also give a rattling series of accelerating cuck notes, trailing off into several loud cowp or cahowp notes. Be aware that Black-billed can also produce series of cuck notes that can fool you into thinking you have a Yellow-billed, so it’s always good to get a look at the bird, too. I have found both to be quite responsive to low whistled imitations of the Black-billed Cuckoo’s calls. I’ve had them come in very close to check out the “competition”. Recorded calls should work too but should not be used frequently during the breeding season.

So, when you’re cursing the caterpillars remember to listen for the cuckoos and try to catch a glimpse of these reclusive and skulking birds.


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