Spring birds are arriving in Connecticut. Eastern phoebes returned recently, and before the end of April we'll be seeing and hearing barn swallows, tree swallows and purple martins.
Those four birds are among 17 species native to our state that eat only insects they catch on the wing.
There's another similarity, too. Since the mid-1960s, all 17 of these "aerial insectivores" have experienced a severe population decline throughout their range, and especially in New England and Canada.
Purple martins, for example, have declined by 40 percent, according to annual breeding bird records kept by the federal government. Barn swallow populations have fallen by 64 percent and chimney swifts by a frightening 95 percent.
As we noted in February in our annual Connecticut State of the Birds report, the causes are likely to include the use (and overuse) of pesticides, global warming, development in open country foraging habitat and the loss of prime nest site locations.
In other words, like most of the problems besetting the natural world, the cause is us — our energy use, our land use, the way we care for the natural world.
Which means, of course, that we also have to be the solution.
We can use less pesticides. Throughout North America, an estimated 67 million birds of all kinds are fatally poisoned each year by agricultural pesticides alone.
We can work on the local level to improve nesting conditions for the handful of aerial insectivores, such as purple martins, that are either completely or largely dependent on man-made nest sites.
And we can increase scientific research and work together on an international and interstate basis to ensure that our best scientists are aware of the issues their colleagues are working on.
Most residents of Connecticut obviously can't participate in basic research to help clarify the cause of the decline of our local swallows, swifts, nighthawks and whip-poor-wills. But we can help in other ways.
We can, for example, reduce the use of pesticides. As their name makes clear, aerial insectivores eat bugs on the wing, and if we kill bugs with insecticides we are killing these birds' only source of food.
Homeowners can switch to organic lawn care products. For tick control, follow the recommendation of the Centers for Disease Control and Prevention and the Connecticut Agricultural Experiment Station: use a tick pesticide just once in spring, rather than regular applications throughout the season.
Connecticut residents can also support pesticide reduction laws in Hartford. The Connecticut Audubon Society is working with other conservation organizations to help pass several this year, including bills that would ban lawn pesticides in municipal parks, allow local governments to enact stronger pesticide regulations than the state, and restrict the use of two specific insecticides — methoprene and resmethrin — in the coastal zone.
Several aerial insectivores rely almost exclusively on man-made nesting sites, and that's another area where individuals can help.
Like bluebirds, tree swallows nest in boxes in open fields (as well as in tree cavities). Landowners with open areas can often attract both species by erecting boxes back-to-back.
Barn swallows, as their name suggests, live in barns, sheds, garages and porches, nesting in the eaves. By leaving a window or barn door open, you can provide easy access to nesting areas for a colony of swallows that will entertain you with their acrobatic flight while helping control insects.
Purple martins will be looking for housing as well. Centuries ago they nested in dead trees and holes in cut banks. Now they need man-made structures such as the familiar elevated apartment-type birdhouses or clusters of natural or artificial gourds located in open landscapes where they can hunt for bugs.
We at the Connecticut Audubon Society have a successful colony at our Milford Point Coastal Center and are establishing another at Stratford Point. We will be contacting local organizations throughout Connecticut to help them determine if they have habitat suitable for martins.
We owe it to these birds to help. We also owe it to ourselves. Purple martins, barn swallows and the other aerial insectivores serve as a good method of insect control — one that comes with beautiful colors, thrilling aerial displays and melodic songs.
Milan Bull is senior director of science and conservation at the Connecticut Audubon Society.Copyright © 2015, The Baltimore Sun