The AC-PROW Project consists of 45 nest structures that I call nestboxes, including 37 nestjars made from four-inch plastic drain pipe and eight wooden or wood/plastic fiber nestboxes. Four of the nestjars have experimental entrances designed to exclude probing woodpeckers. Forty of the project’s nestboxes make up 20 pairs where one of each pair has a 1-1/8 inch entrance that will admit Prothonotaries, wrens and chickadees, and a second box is within five yards away with a 1-3/8 inch opening for Tree Swallows. Tree Swallows provide a second set of eyes to watch for egg-piercing House Wrens and woodpeckers that are endowed with long bills and stabbing tongues.
Each nestbox is attached to a five-foot-long sleeve made from plastic water pipe that slips over a steel pipe that stands in the lake all year long. A steel hose clamp holds each sleeve in place on its pipe. I used my canoe to return all nestboxes from storage to their pipes on April 10 and I monitored all boxes for the first time on May 13, followed by eight more canoe trips until the last boxes were extracted and returned to storage on August 13.
Having raised 209 Prothonotaries since my first nest in 2004, things have been going fairly well until this last season. The 2015 season produced only 16 fledglings, down from 28 in 2014, and the lowest production since 2008.
Male warblers had claimed 16 boxes with moss deposits. Females added their own materials to finish nests in ten of the 16 (62.5%) “male nests”. Young fledged from one of every four (25%) of the original 16 boxes claimed with moss, or four of 10 (40%) boxes that became active with eggs.
The project’s boxes stood along the northern-most rim of Alum Creek Lake and followed the western shore for 8/10 mile running south. The maximum number of active warbler nests occurring on the same date was five on June 3. The average distance between active PROW nests was 293 yards along the western shore.
Since my first PROW nest in 2004, 339 eggs have been recorded, 221 (65.2%) eggs hatched, and 209 (61.7%) fledged. Once eggs hatched, 94.6% fledged. In 2015, Prothonotaries laid 39 eggs, 16 (41%) hatched to fledge. Three monitoring trips were needed to attach U.S. Fish and Wildlife Service leg bands to all nestlings. PROW nests were active with eggs or nestlings for 80 days from May 13 through July 31, 2015.
Why did six PROW nests fail in 2015? House Wrens leave sticks in a usurped nest, or you will find the nest excavated before they add sticks. Four nests left no doubt that wrens were the culprits. One warbler nest lost its eggs sometime after June 4 when a tree fell into the lake to cause the death of three swallow nestlings in the neighboring box. Perhaps, a limb on the falling tree also struck the warbler box enough to shatter its eggs. Adult birds usually consume or remove egg remains.
The last warbler nest failure occurred in an experimental nestjar after one egg was laid and remained in the nest for three weeks before a wren nest appeared. I have no facts to lead to a definite cause for this failure.
As for the four warbler nests that were successful, three families had Tree Swallow neighbors within five yards, and one warbler nest defied all odds by having a House Wren family as close neighbors. Since the brushy habitats that I am working with are only marginal for Prothonotary Warblers, next year, I may locate paired warbler boxes on pipes that are farthest from shore and mount swallow boxes on pipes closest to the brushy shoreline favored by wrens.
As for other native nesters, Tree Swallows attempted 26 nests in 21 boxes. Nineteen nests successfully raised young for a 73.1% nest success rate. Of 158 eggs laid, only 93 (58.9%) hatched and 49.4% of initial eggs developed to fledge 78 young. After hatching, 83.9% of hatchlings grew to fly from the nest. With all the rain that took place this last summer, flying insects were harder for swallows to find, leading to lower than normal success rates. Tree Swallow nests were active with eggs or nestlings for 92 days from May 3 through August 2, 2015.
Even the normally prolific House Wrens were hit hard by weather extremes. As mentioned before, their preferred habitats are thick with brush. Wrens have long legs that allow them to easily hop about in thick brushy habitats in search of insects.
House Wrens attempted 12 nests in ten boxes and successfully raised nine families for a 75% nest success rate. Wrens laid 73 eggs, hatched 54 eggs for an 80.8% hatch rate, and successfully raised 52 young from the original 73 eggs for a 71.2% rate. Wrens fledged 88.1% of hatchlings once they emerged from eggs. House Wren nests were active with eggs or young for 89 days from May 15 through August 11, 2015.
Since the early 1970’s, I have always referred to House Wrens as “Super Bird.” But in 2015, even Super Bird had a rough spring and summer.
At the conclusion of each season, I contemplate what I am going to do about the future of some of my projects that include maintaining and monitoring 388 nest structures. My most recent birthday will be a great day since I celebrate no longer being 70-years-old. And, just as I am close to discontinuing some of my projects, there are always things that spur me on. This year, emails from Dr. Chris Tonra from The Ohio State University announced that he and his graduate students successfully read leg bands from three Prothonotary Warblers nesting at Hoover Reservoir, and as it turned out, I had banded all three as nestlings at Alum Creek and the birds were in their third, sixth, and eighth calendar years of life. According to the Bird Banding Lab in Laurel, Maryland, the oldest Prothonotary captured at Hoover is the second oldest recorded. And, the fact that the banded birds were nesting in 2015 as part of Charlie Bombaci’s highly prolific project was icing on the cake. So in 2016, I will continue banding my yellow and orange beauties at Alum Creek.
Conserve on, and try to ignore the aging process.