On March 19, 2017, twelve nestboxes designed for bluebirds and Tree Swallows were added to a trail of eight boxes that were installed in Smith Park before the 2016 season. Twenty boxes now stand in the drainage ditch inundated with cattails that parallels Troy Road for 400 yards before it veers east into a pond. The boxes are spaced 25 yards apart to allow the target species, Tree Swallows, to nest in peace with their neighbors.
Nesting Red-winged Blackbirds also shared the cattail marsh habitat and occasional conversations with curious park visitors also added to my weekly trail visits.
Swallows built 12 successful nests in ten boxes. Fifty-five eggs were laid, 52 (94.5%) hatched, and 46 (83.6%) fledged. Once hatched, 88.5% of hatchlings matured to fledge into the outside world. The Tree Swallow nesting season lasted 97 days, with the first egg laid on April 28 and the last nestling fledged on August 2 for a typical season.
Due to their diet of small flying insects, Smith Park swallows offered park visitors an environment with fewer mosquitoes and biting deer flies. Based on research that examined and described the diets of swallows, it can be said that for the 45-day period when swallows claim a nestbox and build a nest, lay and incubate eggs, and feed nestlings, the family consumes more than 300,000 flying insects, most shorter than a centimeter. Since the park’s nestboxes housed 12 swallow families, there were 3.6 million fewer insects to irritate park visitors – or to pass on diseases with their insect bites.
On August 14, I winterized the boxes by closing the ventilation slots above the back and front panels. The back panel is closed by tightening two screws after sliding its plastic vent cover up to engage the roof. The front vent is then stuffed with a six-inch piece of felt weather stripping. Studies have shown that bluebirds prefer to roost in winterized nestboxes when they return from their winter homes. Tree Swallows also seek shelter from cold weather when they return. I will reopen front vents during spring cleaning in March, and the back vent will be reopened prior to Memorial Day or before the first days of ninety-degree weather.
The Eastern Bluebird season in the park was a disaster because of alien House Sparrows. I found a sparrow-killed female bluebird during my first round to collect data on March 19. By April 17, four bluebird eggs had been evacuated and the nest claimed by a sparrow. Also, on May 1, I discovered a sparrow-killed female Tree Swallow. Although discouraging, such events were expected due to the proximity of the nestboxes to suburbia. Bluebirds had only one successful nest, but it wasn’t very successful. The nest started with four eggs and only one hatchling grew to fledge. Whatever happened, it took place after hatching0 since I found no unhatched eggs.
I trapped and dispatched my first House Sparrows on March 28, and by the last one on July 1, with a total of 39 for the season. Had I not controlled the sparrows, eight swallow nests would never have been started. Since birds will roost in a nestbox in order to better claim it, I might start controlling sparrows earlier next spring by checking boxes at night with a penlight and machinist mirror.
Last winter was not a good test to see if nestboxes would be adversely affected by dense, heavy snow thrown by snowplows since snowfalls were rather small. Perhaps the upcoming winter will provide a better test. For now, I look forward to next season as veteran nesters and their offspring will be back to fill more boxes with nesting swallows and bluebirds.
Conserve on with nesting Tree Swallows and Eastern Bluebirds!