Nest Boxes at OECC Prairie

The Olentangy Environmental Control Center (OECC) is one of Delaware County’s wastewater treatment facilities and has a capacity of more than five million gallons daily. It serves the Olentangy basin area and is located along State Rt. 315 near the Franklin County/Delaware County line just north of Mt. Air. Highbanks Metro Park is its neighbor across the Olentangy River to the east (map).

Eastern Bluebird (Photo Daniel X O'Neil)

In 1983, I and other members of the Columbus Audubon Society (CAS), installed 15 bluebird nestboxes around two ponds and flowing canals throughout the property. Not only Eastern Bluebirds, but Tree Swallows was a second objective of the conservation project. CAS member Anita King monitored the boxes during its first year to record the fledging of 12 bluebirds and 14 Tree Swallows, and I continued the counts for 37 seasons since.

I added more nestboxes periodically until 29 made up the project by year 2000. By the start of 2001, I added nine boxes in a grid formation of three rows of three boxes each to accommodate Tree Swallows. Also, eleven structures are called nest tubes since they are made from forty-inch lengths of four-inch PVC drainpipe that includes the nest chamber and baffle in one continuous piece. The tubes were added to the riparian habitat along the river and one tube was installed in a wooded wetland in the middle of a grassy field.

Wood Duck - Photo Susan Young

Two Wood Duck boxes complete the project’s total of 52 boxes that I try to check every nine days during the nesting seasons.

My effort to help OECC’s nesting birds in 2020 started on March 15 as I de-winterized the boxes by removing weatherstripping from the front vent slots of the standard bluebird boxes, and removed tape from nest tube vents. Fortunately, I found no winter-killed birds in the boxes. Once the vents are opened, nesting birds can enjoy proper ventilation, and second vents are opened in mid to late May before summer temperature extremes arrive.

Nest tube T-7 presented a special surprise. As I lowered T-7, a flying squirrel’s face appeared in the entrance less than a foot from my face. Yes, we both had a reflexive reaction: I jumped back and the little fuzzy-face continued out the entrance to circle the tube and glide to a tree close by. I had forgotten to bring my camera that day and I vowed to try for a photo on my next visit. Unfortunately, the squirrel was not in the nest chamber on my return visit, only a flat carpet of moss. Perhaps, the nest tube was just a stop over point for the furry glider.

T-11 had another surprise; it was half full of acorns. By April 9, the acorns were gone. Had T-11 been a winter storage depot? Well, I had made up my mind to try to outsmart my furry friends by the 2021 season, but I was too busy to tackle that project until late fall.

There were several other reasons to focus on problems with my riparian nest tubes. First, no chickadees were produced. Only one nest started with seven chickadee eggs and it was ultimately usurped by House Wrens.

Chickadee production has taken a dive since 2015 when the riparian zone raised 39. The yearly production fell from 39 to 25, then 11, 6, 5, to zero in 2020. You can say that there are multiple reasons, but all birds must be well fed in order to court, build and guard their nests, and feed and fledge their young. Once again, I think the largest factor is how climate change is decimating insect populations.

My third concern about my riparian boxes was that I had mounted two nest tubes too close to the river in 2001. Frequently, when the Delaware Dam releases stored water after a flood management episode, high water currents become a reality for T-2 and T-5. Usually the posts are slightly pushed to a small angle and I only have to push them back once the river returns to normal flow. Nesting birds have been good at practicing perseverance and not abandoning nests during rocky times. 

Nest Box Pushed by High Water
On May 24, 2020, T-5 had been pushed by high water from the Olentangy River. The nest tube held wren eggs at the time, and they developed to fledge five.

On May 24, T-5 was leaning considerably after being pushed by a high water flow. After I pushed and pulled it back to stand straight on June 2, I counted five wren eggs, and on June 10, five nestlings were two days old. Analysis of my recorded data revealed that eggs had been in the tube when it was pushed by flood waters. The young wrens fledged around June 24 due to the dedication of their parents. 

T-2 was a different story. High water had pushed it over enough until the current ripped its roof off and away. There was no evidence that a nest had been in the nest chamber during the flooding event. Since I could not find the roof, I removed the tube and its pole from its anchor post and I took the nest tube to my workshop so I could create a new roof.

Dolly For Nest Poles
The dolly transports a post puller, post pounder, pruner, and other tools once they are tied on.

During the second week of November, I returned to OECC twice to make changes. I used my two-wheeled dolly to transport my post puller, post pounder and other tools so I could easily pull T-2 and T-5 and reinstall them on higher ground to avoid powerful highwater currents. I also I shifted one standard bluebird box away from encroaching hardwood trees. I then shifted three tubes that had evidence of flying squirrels into open spaces among the maturing forest. Even though I could imagine a flying squirrel could still glide to the tubes from tall trees nearby, the squirrels would feel insecure with not being able to glide from the tube’s roof to a tree trunk close by. I was thinking that the squirrels would not be comfortable running on the ground to a safe tree. I have to admit that my assumption might be wrong.

If you are interested, the Internet has a lot of information about flying squirrel conservation, including nestboxes for sale, plans for boxes, and many other topics. They are fun animals and it might be exciting to help them out.

Bird production at OECC is disappointing when compared to values for 2019. Bluebird production decreased 54.8%, Tree Swallow production fell 32.3%, and House Wrens dropped 14%.    A closer inspection of my data reveals that bluebirds attempted 13 nests with eggs and seven nests (53.8%) successfully  produced fledglings. Wrens had caused two failures and causes for four failures were undetermined. Bluebirds laid 47 eggs, 29 (61.7%) hatched, and 19 (40.4%) fledged. Once hatched, 65.5% became fledglings.

Tree Swallows started 22 nests and 17 (77.3%) became successful. Swallows laid 105 eggs, 72 (68.6%) hatched, and 65 (61.9%) fledged. Once hatched, 90.3% fledged. Among the five nest failures, House Sparrows wiped out one family by killing six swallow nestlings. Two nests failed due to conspecific competition, and two failures were undetermined.

At least ten pairs of House Wrens started 18 nests and 13 (72.2%) became successful. Flying squirrels caused one wren nest failure while four nest failures remain mysteries. Wrens laid 101 eggs, 70 (69.3%) hatched, and 63 (62.4%) fledged, for a fledge rate of 90% for hatchlings.

In a successful attempt to stop the carnage brought on by alien House Sparrows, VanErt sparrow traps were used to catch nine sparrows that were humanely euthanized and stored in plastic bags in a freezer with other sparrows awaiting delivery to museums at Ohio State and Ohio Wesleyan Universities, and some have already been delivered to recuperating accipiters and owls at the Ohio Wildlife Center.

A Wood Duck fledged eight ducklings in the most northern box, then egg dumping took place as two females laid 14 more eggs. The wetland dried up and the later eggs were abandoned after partial development took place. I removed the decomposing eggs on August 23.

The southern wood duck box became the home to Carolina Wrens that laid their first of five eggs on July 17, and all hatched and everybody fledged around August 18. Carolina Wrens nesting in wood duck boxes is becoming quite common.

Nest Boxes at OECC Prairie
On July 26, 2020, nestboxes stood among blooming prairie plants at the OECC.

Another positive note; OECC has a native plant prairie that was planted two springs ago, and it was flowering quite well this past season. It adds flowers and butterflies to the grounds between OECC’s eastern pond and the driveway that borders the wooded riparian habitat. Four and five boxes make up two rows of evenly spaced prairie nest sites to satisfy Tree Swallows, and bluebirds always claim the highest prairie box that stands a knoll.

Two deer were grazing in the prairie on July 16, and I saw my first grasshopper there on July 25. On August 3, a flock of eight Goldfinches flew off to produce a powerful, spiritual boost for my day.

And yes, I always enjoy the Canada Goose families that inhabit the center’s ponds and canals along with its grassy habitats. Thanks go to the maintenance team that mows around some of my boxes and I keep them informed with mailed score sheets after each of my visits. Conserve on!