In 2017, two nestbox grids of 25 and 32 boxes, respectively, raised a total of 214 swallows and 12 bluebirds on the Delaware Wildlife Area.
In 2018, 25 boxes making up the Leonardsburg Road Grid were moved to join 30 boxes to make a grid of 55 boxes within a five-acre field on the west side of Panhandle Road. When a pair of boxes’ totals on the east side of Panhandle Road was added to the west side’s totals, the 57 boxes raised 250 swallows, six bluebirds, and ten House Wrens for a successful conservation maneuver that was also inspirational.
Eleven rows of nestboxes, from two to eight boxes per row, make up the grid. Most are spaced 25 yards apart, and three boxes are spaced closer to avoid brush. The grid offers a symmetrical sight for dog walkers, joggers, hikers, bikers, birders and others just passing by.
During fall and winter, the project’s nestboxes are stored on my back porch in order to avoid unintentional shotgun pellets during hunting seasons. Between February 11 and 18, I returned the boxes to their mounts in order to accommodate any bluebirds looking for a place to nest. During the first three weeks of April, I trapped and dispatched two male House Sparrows after they had killed two adult Tree Swallows.
On April 25, I found an active bluebird nest with one egg in Box-50. After finding the bluebird nest, I returned to my hobby car to retrieve a post pounder, a T-post, a baffle, a pipe extension, and Box-X. I installed Box-X six yards Northeast of Box-50 so a Tree Swallow family could nest in harmony with the bluebirds. During the same visit, I also recorded 43 Tree Swallow nests in different stages of construction. The nesting season had been launched!
The bluebirds in Box-50 raised two families of three fledglings each and the second family fledged around July 19.
Pairing worked and all 57 box locations fledged swallows after Tree Swallows laid 344 eggs, 278 (80.8%) hatched, and 250 (72.7%) fledged. Once hatched, 89.9% of hatchlings grew to fledge. The earliest swallow first-egg-date (FED) was May 6, and the latest FED was June 22; both record dates took place in Box-41, the only box to produce two swallow families.
During the 2018 season, swallows had only four nest failures among 62 nest attempts for a 93.5% success rate. After failures took place, successful second attempts followed in the same boxes.
As I monitored the PRG throughout the summer, I was inspired by a sky filled with graceful birds flying to, from, and around their boxes. Of course the determined swallows also frequently dove at me to sustain the smile on my face.
Many times memories surfaced and took me back to when I experienced my first beaver ponds inside Isle Royale National Park during four backpacking tours that started in the 1970’s. The island’s beavers had built dams that flooded woodlands and smothered trees. Some trees had been girdled as the rodents sought nutritious cambium layers beneath the outer bark. Other trees were felled to provide building materials for their dams and some branches were anchored on the ponds’ floors so their bark could provide winter nourishment.
Trees left standing were in different stages of rot and some had cavities that had been whittled by woodpeckers seeking insects. The cavities served as nest sites for cavity nesting birds, including Tree Swallows.
In 2000, I explored more beaver worlds in Burr Oak State Park near Athens, Ohio, and by early 2001, I had produced a slide Program entitled, “The Beaver Hypothesis: Bluebirding in the Seventeenth Century.” The program offers evidence that Tree Swallows and bluebirds depended on beavers for habitats with nest cavities that dominated North America before Europeans arrived to harvest beaver pelts. The hypothesis offered that bluebird nestboxes mimic the availability of natural nest cavities in and around beaver ponds, and given enough time, modern Tree Swallows will reclaim their ancestral nesting range that coincides with the original land area claimed by beavers throughout North America.
In 1935, and as recently as 1980, Tree Swallows were not nesting anywhere south of the upper two thirds of the state of Ohio. Today, the white-bellied swallows nest in all Gulf States to support my hypothesis. In ancient times, nesting swallows could thank beavers for their nest sites, while today’s swallows can thank conservationists for nestboxes throughout North America that mimic the evenly spaced cavities found in beaver ecosystems. In 2005, beavers provided more adventures within the Delaware Wildlife Area’s Green Tree Marsh after I launched a project to raise Prothonotary Warblers.
This year, another world was revealed after the nesting season when it was time to remove nestboxes and baffles from their posts to be stored at my home before September’s hunting seasons. One hundred-fifty-one frogs were found using the inside surfaces of baffles for shelter. Baffles are 33-inches long and are made from four-inch plastic drain pipe. Twenty-two frogs were also found inside nestboxes. Gray Tree Frogs made up the super majority and several Spring Peepers were also encountered. If someone wants to conserve some of our small frogs, I’ve got a good idea for you!
Nestbox posts are steel sign posts supplied by the division and the small frogs find the flat surfaces easy to climb while using their round, flat toes. At my other nestbox projects, I always smear grease on the posts inside baffles to deter most ant species from invading bird nests. In an agreement with the division, no grease is used on posts at the wildlife area so hunters and their dogs need not worry about getting smeared. Of course, this respectful policy is also good for the frogs.
Unfortunately, 36 baffles were homes for paper wasp nests and I sustained four wasp stings before I completed my job. Only two nestboxes contained active wasp nests that I had failed to see and evict during normal monitoring visits during the nesting season.
I am still impressed by the Tree Swallows’ nesting success. A minimum of 58 pairs of eyes watched for hawks and invading House Wrens. Wrens were kept at a distance until the colony had raised most of their young. June 24 and July 6 were the First-egg-dates for the only two House Wren nests.
As I have stated frequently in the past, our Tree Swallows consume more than 300,000 flying insects during the 45-day period that they use our nestboxes to raise their families. Using a conservative value of 58 successful swallow families, our efficient white-bellied friends consumed 17.4 million flying insects as they gleaned the sky up to 40 feet above the ground. I never need to wear insect repellant when my swallows are nesting en masse. Conserve on!