Spring is a time of expansive abundance. From white-tailed deer fawns trailing behind their mothers to black bear cubs bumbling through our forests, the Upper Delaware River region is filled with new life. Unfortunately, among the critters you’ll find in greater numbers this year are the hairy caterpillars that can be seen crawling and dangling all about. 

It’s likely that this food resource led to the tragic death of a yellow-billed cuckoo that crashed with great force into a window at my home recently. This beautiful species has a particular fondness for hairy caterpillars and during outbreaks like the one transpiring here recently, cuckoos provide the valuable service of reducing the numbers of these pests.

In my yard in Pike County, PA, the caterpillar population is so high that many are dangling from trees surrounding the sun porch where the cuckoo met its fate against a window. It’s possible the bird was attempting to harvest a caterpillar dangling in front of one of the windows, as birds have difficulty distinguishing glass from what may appear to be an opening they can pass through. Windows that reflect foliage or sky, as well as windows with potted plants on the other side are particularly conducive to creating the illusions that lead to collisions.

The Cornell Lab of Ornithology reports that up to approximately one billion birds die from window strikes annually in the United States. Ongoing research is leading to better understanding of what can be done to help our avian friends avoid a fatal flight. Screens can help, but aren’t always effective, as in the case of this cuckoo. 

Note that while applying decals to windows may reduce strikes, research has shown that hawk and owl silhouettes are now considered ineffective. 

Visit the following links to learn more about the latest options and to find information on how to help a window collision victim.

https://abcbirds.org/glass-collisions/stop-birds-hitting-windows/ 

https://www.allaboutbirds.org/news/how-can-i-keep-birds-from-hitting-my-windows/ 

https://www.allaboutbirds.org/news/why-birds-hit-windows-and-how-you-can-help-prevent-it/