Disappointment, success, and new ideas made my efforts to help golden swamp warblers challenging in 2016. As I have reported before, my project of 45 nestjars and nestboxes is located on Alum Creek Lake along its northern and western shores opposite Hogback Road in Delaware County southeast of the small village of Kilbourne. Pipe posts stand in the lake all year while nestboxes are mounted on five-foot-long sleeves made from 1-1/4-inch water pipe that are stored at my home between nesting seasons. In most cases, nestboxes with 1-1/8″ openings for warblers are paired at least five yards from nestboxes with 1-3/8″ for Tree Swallows. As swallows guard their own nests from egg-piercing House Wrens, they inadvertently protect Prothonotary nests at the same time. At least, that is my wildlife management objective.
Five warbler nests successfully raised 20 fledglings after 26 eggs were laid among seven nests. All hatchlings fledged wearing U.S. Fish and Wildlife Service aluminum leg bands. All successful warbler nests had nesting Tree Swallow neighbors and House Wrens caused two other nests to fail. One warbler nest failed after neighboring swallows left the area once their family fledged.
Most disappointing was that no warbler eggs were laid past June 30 and that latest nest fell victim to wrens. In 2013, warblers laid initial eggs for three nests on July 11, 12 and 14, respectively, but only the latest nest became successful. I waited past mid-July this year before I started pulling boxes to store them for the winter.
The earliest warbler egg appeared on May 15. The latest first-egg for a productive nest was laid on June 1, and that nest was great news since it occurred in an experimental nestjar made to exclude predatory woodpeckers. In 2016, Prothonotary nests were active with eggs or nestlings for 47 days from May 15 through June 1. The 2013 season was nearly twice as long at 92 days from May 7 through August 9.
Since 2013, I have offered Prothonotaries four experimental nestjars that are designed to stop Red-bellied and Red-headed Woodpeckers from leaning into nest chambers. Both woodpecker species use their barbed tongues to spear eggs and nestlings of other birds so they can have an avian feast for themselves and their young. At Alum Creek, all of my anti-woodpecker nestjars are fitted with 1-1/2″ male adapter fittings (plumbing terms) with enough 1-1/2″ PVC water pipe glued in place so that a 2-1/2 inch tunnel sticks out from the nest chamber after being glued in place with epoxy. Each fitting offers a tunnel 1-1/2 inches wide on the inside and I smear epoxy unevenly to the tunnel’s floor to promote traction for the birds. For two of the four jars, I made flat plastic restrictors with 1-1/8″ openings and 1-1/2″ diameters, and I glued them to tunnel ends to create smaller entrances, and it was one of those nestjars that produced three warbler fledglings this year (see photo).
I point all boxes intended for swallows toward the lake since they approach their boxes from open water. In the past, I might have been inadvertently encouraging wrens by pointing warbler boxes toward the forested shore, thinking that warblers would be approaching nestboxes from the land rather than the lake. If I continue my project next year, I will point all boxes toward the lake until I band warbler nestlings, then I will aim their boxes so nestlings will be able to see land before their first flight.
The project’s Tree Swallows had a good year and their season was 80 days long from the first egg on May 7 to the last fledging on July 25. Swallows attempted 24 nests and 20 (83.3%) raised young. Swallows laid 120 eggs, 85 (70.8%) hatched and 83 (69.2%) fledged. Most astounding, 97.6% of hatchlings grew to fledge.
The House Wren season lasted 91 days from May 8 to August 6. The wren’s season was truncated due to the fact that I pulled boxes and their sleeves from their posts to store them for the winter. I obey the law and I pull boxes only after families fledge, but if I did not pull boxes after the Prothonotary and swallow seasons, wrens would add more nests to fledge young into the first days of September. Wrens laid 76 eggs, 64 (84.2%) hatched, and 58 (76.3%) fledged. Once hatched, 90.6% fledged while only one nest of six nestlings failed. All six nestlings disappeared, leading me to suspect a woodpecker as the best candidate to explain the mystery.
I would like to learn how far from shore Prothonotaries will nest but the gamble is not worth it since a glancing blow from a boat will shatter eggs. The growing popularity of kayaks and canoes dampens my desire to move boxes further out from the brushy shore. That is a reality that I must live with.
My effort to raise golden swamp warblers at Alum Creek Lake remains a physical challenge, but one that is worth it. In addition to what I have seen inside my nestboxes, as I paddled my route, I enjoyed glancing up to watch an Osprey family living their lives in a natural nest while our nest platforms standing in the lake’s middle provided other attractions. Great Blue Herons and Cormorants were also common along with clusters of young Wood Ducks that had fledged from four nestboxes in the area. Interesting conversations with boaters and folks trying their luck at fishing have always been added benefits.
My Prothonotary Warbler project remained a physical challenge since I had to launch my fifty pound canoe eleven times to manage the 2016 season, but for now, I plan to continue.
Paddle and conserve on!