The Saga Begins
Fifty years ago, “white-bellied swallows” were rare nesters in Central Ohio, occasionally nesting in Wood Duck boxes. But during the last thirty years, they have become quite common in Delaware County and throughout Ohio due to the popular hobby of “bluebirding.” The quest to help nesting bluebirds has also offered safe nest sites for Tree Swallows.
I started bluebirding in 1968 and nine years later, in 1977, my first two pairs of swallows nested and raised five young between them. Swallow populations grew every year and within a decade, my nestboxes were fledging more than five hundred swallows annually. I added more boxes at more locations, until more than a thousand Tree Swallows have fledged each season for four of the last five seasons. During the past 34 seasons, 21,626 fledglings sporting white bellies and charcoal-colored backs have emerged from my nestboxes.
A Swallow’s Diet is its Best Ambassador
Tree Swallows owe a lot to bluebirds for inspiring people to erect nestboxes. A bluebird’s beauty spurs many nature watchers to step forward and become “bluebirders” who install and monitor multiple series of nestboxes along “bluebird trails” on private properties, campuses, golf courses and parks. Along with the bluebird’s hue, the Tree Swallow’s iridescent back and graceful flight also recruits fans to practice effective conservation while their little-discussed diet remains their best-selling point to those not participating in their conservation. Even those most blind to nature can be convinced that nesting Tree Swallows should be encouraged to share our world once the quality and quantity of Tachycineta bicolor‘s diet are revealed. Scientific investigations by ornithologists found that Tree Swallows spend 90-percent of their hunting time snatching insects within forty feet of the ground. Ninety-nine percent of a Tree Swallow’s prey is shorter than a centimeter, which is one-half the width of a nickel. And, an adult bird can gobble 2,000 tiny insects a day while they deliver 6,000 insects a day to their nestlings. While flying and snatching prey, a parent bird uses its tongue to roll an average of 18 insects into a round ball called a bolus that it stuffs into a nestling’s mouth at the nest. During a conservative 45-day period when swallows use a nestbox to raise a family, from nest building to fledging, each family consumes more than 300,000 insects. If I apply that number to 252 successful nests on my trails in 2009, then my swallows consumed more than 75.6 million flying insects around their nest sites. In 2010, my swallows consumed 67.8 million insects while raising 226 families.
The estimated number of flying insects swept from the sky becomes even more immense when we consider the swallow’s calendar. Swallows return from migration to claim nestboxes around mid-March, and they don’t lay first eggs for six weeks or so. Their earliest eggs appear during the last week in April. Then, after their nesting season ends by the first days of August, they abandon their nestboxes and stage in large flocks before making exploratory flights to northern regions before flying south to their wintering grounds along the southern coast of the U.S. and into Central America. Wherever they are found, swallows snatch mosquitoes, biting flies and other winged vectors to suppress the spread of diseases that would normally infect mankind and the furred and feathered.
Tree Swallow Nestbox Grids
During the 1980’s, ornithologists revealed that Tree Swallows can successfully nest in nestboxes evenly spaced at 20-meters (21.9 yards) apart. Tree Swallow nestbox grids are concentrations of nestboxes that mimic spacing of natural nest sites above beaver ponds. I hypothesize that before bluebirding, the North American beaver was the Tree Swallow’s landlord. Dams constructed by these flat-tailed bluebirders flooded woodlands, and woodpeckers whittled the dead trees left standing to create evenly spaced nest sites for swallows, bluebirds, and other cavity nesters.
Ohio was a much wetter place before Europeans established colonies in Quebec City, New Amsterdam (NYC), and elsewhere that sought beaver pelts and other furs. Today, most teachers and naturalists describe the earliest days of Ohio “at the time of settlement,” but decades before Ohio became a destination for farm families, trappers of many nationalities removed the influence of Ohio beavers during the seventeenth and eighteenth centuries. By the time the last Ohio beaver was removed in 1830, most beaver dams had eroded, their wetlands had drained, and skeletal trees that had stood in the flooded woodlands continued to decay as the beavers’ former world succeeded back to forests. Once farm families arrived, Ohio’s woodlands were chopped and its remaining wetlands were drained to support crops.
As swallows lost their chance to nest as colonies in clusters of evenly spaced natural cavities, their nesting range gradually retreated north. My earliest field guides from the mid-1970’s show that Ohio’s swallows nested along Lake Erie (and North). Thousands of bluebird conservationists have been installing nestboxes across North America since the movement took off after the founding of the North American Bluebird Society in 1978 (and the publication of “Hit the Trail for Bluebirds” by the Ohio Division of Wildlife in 1977). Tree Swallows have responded by nesting farther south each year, and today, they nest well into the Gulf States. In other words, swallows have been reclaiming their historical summer range that they once shared with beavers. Bluebirders have become modern landlords for Tachycineta bicolor.
Central Ohio Grids for Tree Swallows
I have been promoting swallow grids for the last eleven years. I maintain four grids of my own totaling 70 boxes, and I have donated a 16-box grid to Old Woman Creek in Huron County. Also, I installed grids at the City of Delaware’s WasteWater Treatment Plant and Gallant Woods Preserve, and helped Girl Scouts install a grid at the Stratford Ecological Center. Darlene Sillick has drafted my help with grid installations at the Ohio Wildlife Center, the Columbus Zoo, Glacier Ridge Metro Park, and one in Dublin. Most grid boxes are spaced at 25 yards apart, but where space has been limited, 22-yard spacing has worked well for happy nesting.
My favorite grids are located on the Delaware Wildlife Area. The Panhandle Road Grid consists of 27 nestboxes in rows of two to six boxes. The Leonardsburg Road Grid is a square grid of five rows of five boxes each, making 25 nestboxes within a square that is “as long as a football field on each side.” Fields hosting both grids are managed grasslands, and the Leonardsburg Road grid can be so wet that I need to wear knee boots to monitor the boxes there. During most springs, kestrels nesting in their own nestbox (K-17) hanging from an electric pole, endure harassment from swallows as they sit on the flat nestbox roofs throughout the grid, and stalk Spring Peepers and other small frogs below.
In 2009, every grid box in the wildlife area produced swallows. Some nests failed, but second attempts made the impressive outcome possible. Overall, eggs appeared in 62 nests and 56 (90.3%) produced 242 young.
In 2010, a pair of bluebirds in the wildlife area made sure not all boxes would produce swallows when they raised two broods of their own. Mother Nature also threatened swallow production when temperatures dipped into the mid-thirties during the second week of May, causing 12 clutches of swallow eggs to “disappear.” The eggs didn’t go anywhere; they had been buried under succeeding nests after cold temperatures grounded insects. Incubation is an energy-sapping behavior and to save their own lives, females had to abandon their first eggs. Life goes on, so after warming temperatures delivered food on the wing, swallow hormones cycled back to induce another round of nest building and egg laying that ultimately led to 50 successful nests fledging 220 young after 70 nest attempts. Such events teach us that used nests should be pulled apart during box cleaning to reveal any “hidden histories.” Only then can the most accurate observations be recorded in data books.
Every Nesting Season is Unique
In 2009, swallows claimed boxes on nine of my trails, and Delaware State Park led the count by producing 389 aerial feeders. Overall, swallows raised 1059 young after laying eggs in 306 nests. Fledglings flew from 252 nests, representing 82.4% of the nest attempts, for an average yield of 4.20 fledglings per successful nest. The 89-day long nesting season in 2009 lasted from the first egg on May 2 until the last nestling fledged on July 29.
2010’s season lasted 85 days from the first egg on April 21 to the last fledging event on July 14. Swallows raised 1002 young from 226 nests after 320 attempts with eggs for a 70.6% nest success rate. The average yield was 4.43 fledglings per successful nest.
Dealing with the Reality of Alien House Sparrows
Farms with open feedlots and homes with bird feeders support House Sparrow populations that will invade nestbox projects in search of nesting sites. When a male sparrow invades a grid, it usually hops from box to box and uses its thick, sharp weaver finch beak to peck open the skulls of several to as many as six swallows in its frantic bid to claim one nestbox. It is my job to trap and kill House Sparrows. Each of my nestboxes is equipped with two screws below the inside surface of the front panel that accepts a Universal VanErt Sparrow Trap. The trap does not harm captured birds so native species can be released unharmed.
In 2010, I legally removed 46 sparrows from my nestboxes but not before the murderous serial killers wiped out the following nests: three Eastern Bluebird nests, including eight eggs and three nestlings; seven Tree Swallow nests, including five eggs, 22 nestlings, and two adult swallows; and one adult House Wren.
Feather Tossing
Anyone can enjoy helping Tree Swallows even when not erecting nestboxes: you can toss feathers for them. Female swallows line their nests with white and gray feathers. After she builds a grass or pine needle nest, the female lines the off-centered cup with feathers. Female swallows are nest architects while males provide most of the feathers for them. Feathers cover and conceal eggs and camouflage nestlings that sprout gray down after hatching naked.
First, feathers gathered by our species must be legal, so limit your gathering to domestic fowl or game birds if you are a licensed hunter, etc. To be sure you are legal, tear apart an old down coat, pillow, or blanket and recycle its feathers for many years of tossing. Feathers from the breast and bellies of chickens work best because they float easily when released into the air. Tossing feathers near a grid causes a frantic shopping spree, and most exciting are the hand-offs. A male carries his prized feather back to his nestbox, and sometimes his lady awaits him by perching in the entrance. Cheers from excited feather tossers usually accompany a successful hand-off. It is also fun to toss a large feather that causes aerial fighting among the males. Three or more birds will grab-and-drop the same feather multiple times before a successful delivery takes place.
I first tossed feathers in 1979 for Delaware State Park’s first swallows. When I cleaned pheasants after a successful hunt back then, I always skinned my harvest to save colorful feathers for my mother who glued them to decorate women’s hats. When I tossed the golden feathers into the wind for those first swallows, they gingerly plucked them from the air and I looked forward to finding beautifully decorated swallow nests. Days later, I was somewhat disappointed to find the golden pheasant feathers sandwiched out of sight under gray and white gull feathers. Nonetheless, I was still impressed with the final product.
Feathers of any color will insulate eggs and young and studies have shown that the rate of nest success increases as the number of feathers buildup. Swallows collect feathers during nest-building, egg-laying and incubation periods. I have noticed that once Canada Geese debut their golden goslings, goose feathers are found packed in nearby swallow nests. Swallows mine goose feathers from abandoned nests and they know how to recycle!
Plan to include feather tossing in your birding trips. Find a grid, park safely, and start tossing. May is the best month for tossing but swallows will snatch feathers from mid-March through June, but only if their bellies are full. So, plan to toss on warm afternoons so your efforts won’t be ignored. Also, feather tossing is a great way for children to interact with wildlife in a safe and positive way. Sometimes, if visitors have tossed before, the grid birds will quickly recognize your intentions and graceful, but intense, swallows will surround your party. Sometimes, if you stand still and hold your feather high, a swallow will take it from your hand. Toss on for many spiritual encounters in the outdoors!