So maybe it's not nesting sites. Maybe it's the pesticides and fungicides we're spreading on lawns and crops to kill the bugs these birds are eating.
Reducing the number and types of bug poison being put into our environment seems to be the one area Connecticut Audubon Society experts believe we can act on immediately. They are calling for state legislation to ban the use of pesticides and herbicides on public parks except in emergencies, and to force a cut back in the amount of these poisons used on private lawns.
"That's something we can do right now," says Bull. "It's good for people as well as for aerial insectivores."
Those proposals are certain to generate huge opposition from the lawn care and pesticide industries, as well as from homeowners and municipal officials who love their grass.
But just as important, according to the Audubon Society report, is a concerted effort by state environmentalists, the federal government and academic researchers to learn about our aeroecology and the creatures that depend on it.
"A serious problem exists," Robert Martinez, president of the Connecticut chapter says in his introduction to the 2013 report. "Aerial insectivores are in critical decline, but there is not nearly enough research to know for sure why."
"We really need to know a lot more about what's going on," says Bull.