Prothonotary Warbler Adventures: 2020

Prothonotary Warbler right - Photo Earl Harrison

The quest to attract nesting “golden swamp warblers” starts with re-establishing their nesting structures at two locations, Alum Creek Lake near Kilbourne, Ohio, and along the original Leonardsburg Road in the Delaware Wildlife Area.

At Alum Creek, forty-five pipes stand in the lake all year near the northern and western shore for a shoreline distance of more than a mile. The pipes stick up three to five feet above the summer pool of 888 feet above sea level, managed by the U.S. Army Corps of Engineers at the lake’s dam. Nestjars made of four-inch PVC drain pipe and nestboxes constructed from wood and other materials are attached to five-foot lengths of one-inch plastic water pipe that function as sleeves to slide over the steel pipes to hold nest structures more than six feet above the lake after I tighten hose clamps that I adjust from my rowboat. My boat is an Old Town Stillwater-12 that is extra wide and designed to be extra stable for duck hunters and fishermen. A length of rope with carabiners at each end allow me to safely snap the rope from my boat to around the pipes so I can stand and lift the nest structures to slide their water pipe sleeves over, and onto, their steel pipes.

During winter months, the lake’s water is lowered to 885 feet above sea level for numerous reasons. At 885 ft., the lake’s bottom is exposed at its northern end, so on March 13, 2020, I did not need my boat to reinstall 14 structures in the vicinity of most northern Osprey platform, AC-1. I wore hip boots that fasten to my belt so the thick sticky mud could not pull my boots off. Knee boots will not work in thick, sticky mud. During my first reinstallation episode, I counted four Tree Swallows that were glad to see their nest structures; sometimes they would land to look in the entrance hole before I was done adjusting the box’s height.

By April 2, the lake was at 887.4 feet and I used my boat to reinstall the middle 15 nest structures that restored the project past Osprey platform AC-3, and the next day, I finished installing the last 16 to await the arrival of the prothonotaries, House Wrens and more Tree Swallows.

Boxes and jars are paired around five yards apart with one structure that has a 1-3/8 inch entrance for swallows, and the other has a 1-1/8 inch opening for warblers and wrens. The management goal is that swallows swoop at, and discourage wrens, and protect warbler nests in the process.

I made six boat trips to collect data on how things were going. The earliest Prothonotary Warbler egg was laid on May 20 and the latest first egg was laid on July 8. The latest fledgling took place around August 1, all to make a 78-day season of active warbler nests for the 2020 season.

Prothonotary Warbler Removing Fecal Sac from Nestbox - Photo Frank Germann

A 2008 photo by Frank Germann shows the main features of a nestjar with a Prothonotary Warbler removing a fecal sac.

The warblers attempted nine nests with eggs, and only two failed due to House Wrens. So, 77.8% of nest attempts were successful after 45 eggs were laid, 28 (62.2%) hatched, and all (62.2% of eggs) fledged. Of course, since all (100%) hatchlings grew to fledge, 2020 was a great year for my prothonotaries.

Tree Swallows attempted 21 nests with 107 eggs and only one nest failed for unknown reasons. A nest success rate of 99.1% sounds good until a further analysis takes place. Ninety-five swallow eggs hatched (88.8%) but only 75 (70.1% of eggs) developed to fledge. A 78.9% fledging rate for hatchlings reveals that the food supply of flying insects was lower than earlier years since swallows usually fledge around nine of every ten of their hatchlings. Furthermore, at the end of the season, it is not pleasant to find the remains of twenty young swallows when their used nests are removed from their cavities. The active nest season for the swallows lasted for 90 days from the first egg on May 8 to the latest fledging on August 5. None of the swallows attempted second nests, another symptom of low populations of flying insects.

House Wrens earned their nickname, super bird, that I gave them decades ago. Wrens attempted 25 nests, and 24 were successful for a 96% rate. They laid 129 eggs, 118 (91.5%) hatched, and 116 (89.9%) fledged for a 98.3% fledge rate for their hatchlings. Yes, they earned their nickname as they foraged the brushy shoreline for small insects and other life forms to feed their young. The efficient wrens established a 73-day period of active nests from the earliest first egg on May 12 to the last nestling flying from its nest on July 23.

There’s more than birds going on at Alum Creek Lake; the joy of kayaking has been discovered by many people of all ages. And, the kayakers enjoy the visual encounters with the Osprey, prothonotaries, swallows, and even the wrens. I’ve had many conversations, been told of natural nests along my route, and answered many questions, and since cell phones enable their owners to be wildlife photographers, I’ve enjoyed watching boaters capturing images of “my birds” tending to their families.

Another successful prothonotary nest took place on the Delaware Wildlife Area north of Delaware. As Leonardsburg Road crosses Horseshoe Road and passes over a tall levee that holds flood waters for Delaware Lake, the willow saturated wetland on the north side of the road is a “green tree marsh,” a wildlife management term that describes a woodland flooded to benefit wetland wildlife that copies what beavers do. If you want to add Red-headed Woodpeckers to your list, this is the place to visit.

One nestbox and four nestjars stand in water, parallel to the road, and I usually wear chest waders for monitoring. This year, the water had been raised to a higher level so the wildlife division could flood adjoining fields in order to wipe out unwanted vegetation. I had to launch my boat five times for very short, pleasurable glides to record data. The five structures fledged three Tree Swallows, two families totaling 11 wrens from one jar, and one family of five golden swamp warblers from another jar. A pair of additional boxes stands on land overlooking the marsh and one of the boxes raised six wrens.

Since my first PROW nest raised two from four eggs at the Izaak Walton – Columbus Zoo Nature Preserve in 2004, my projects have raised 366 of the only cavity nesting warbler east of the Mississippi River. Like the bluebird, their beauty is their best promoter, so let’s see more nestjars and boxes out there!

Conserve on!