The 17th Year Feast

Corey HusicGeneral News and Info, ScienceLeave a Comment

Anyone who has stepped outside in New Jersey or eastern Pennsylvania this month has likely heard the cacophony of millions of periodical cicadas that have emerged from the ground and headed to the trees to breed. With their loud calls from the treetops, even a small chorus of these odd insects is enough to drown out birdsong. Luckily, this noisy phenomenon only occurs every seventeen years, when Brood II of septendecimal cicadas emerges from the ground, and these black-and-orange bugs reach their adult life stage.

The noise is certainly a nuisance, but these plump insects also provide an excellent food source for many bird species. Larger insect eaters, say, cuckoos, will happily gobble down several cicadas in a sitting as they move about the canopy. Other species, like Great Crested Flycatchers can be found plucking the cicadas out of the sky as the insects attempt to fly from tree to tree. I even witnessed Tree Swallows diving on flying cicadas, although they were unsuccessful at catching any. Northern Flickers will eat the shed exuviae (exoskeleton remains after the cicada’s final molt) in addition to the live insects.

Southern New Jersey saw an influx of Mississippi Kites into the region in the first half of June. These insectivorous raptors are likely taking advantage of the plentiful and protein-filled feast in the mid-Atlantic. It is possible that these kites and other species will move out of their typical ranges because of the cicada emergence.

While my personal observations seem to suggest that birds have been more abundant this year (or at least more apparent), a study from the Cornell Lab of Ornithology suggests that bird populations tend to be lower on years with periodical cicadas. The researches suggest a number of possible causes, although more work is needed to determine the reason. Nevertheless, here in my region of Pennsylvania, I have seen more cuckoos and Great Crested Flycatchers (the species I most frequently see consuming cicadas) than most other years!

Although the peak of the emergence is over, thousands of cicadas can still be found in wooded areas, so if you listen to me instead of Cornell and follow the cicada chorus, you may be rewarded with many birds. Just don’t expect to hear them singing!