One of the five nests was located in the Green Tree Marsh, a flooded woodland on the Delaware Wildlife Area. The marsh is a sure bet for those needing to add a Red-headed Woodpecker sighting to their lists. Tall, gray skeletons of flooded trees stand on both sides of historic Leonardsburg Road and provide nesting and feeding opportunities for woodpeckers. Prothonotaries also nest in woodpecker cavities where they can drop to hunt insects, caterpillars, and spiders among the shorter willow trees that have invaded the swamped forest floor. The marsh is walled on two sides by a levee that allows Delaware Lake to swell with floodwaters while protecting the City of Delaware from disaster as it did in 1959 and 2005.
Last April 15, I parked my car along the wildlife area’s gravel road and waded back and forth to erect six nestboxes among two openings surrounded by willow trees. I offer three types of nestboxes to my warblers. Most are made from four-inch PVC drain pipe in nine-inch lengths and are capped, shaded and insulated by PVC fence railing. Once assembled, the nest jar is almost identical to the PVC bluebird nestbox found on page 105 of The Bluebird Monitor’s Guide, except for the 1-1/4 inch entrance hole. I call them “nest jars” since they are fashioned after a successful project started in 1992 where plastic Metamucil® jars were mounted on telescoping PVC pipe sections to accommodate nesting warblers along the Upper Cuyahoga River in Geauga County. Some of my warbler boxes are made of wood, and others are made from a dense composite of sawdust and recycled plastic milk cartons. All of my nestboxes stand six or more feet above the water, higher than most historic flood levels.
After I installed the nestboxes in the marsh, the stage was set for the procreation of three species and the cast of feathered characters did not disappoint. A pair of Tree Swallows raised five. House Wrens fledged four, and the target species produced five “willow warblers.” The first eggs among the three neighbors appeared between May 16 and 24. The swallows and warblers nested five yards apart and it is possible that the Tree Swallows protected the warbler nest from egg-piercing wrens. When I sat in my car and watched parents deliver food to nestlings, swallows fed five or six times for every appearance by a warbler. Wrens readily retreat from aggressive swallows and prothonotaries, so Jenny wrens seemed content to stay near their own clearing beyond a stand of willow trees.
Prothonotary Warblers can behave in unique ways that contradict what we expect. Skip Trask of the Ohio Division of Wildlife met me at the marsh at noon on June 16. He wanted to capture footage of adult warblers and my banding procedure for the Wild Ohio TV series. We stood in knee-deep water as Skip operated his video camera as I lowered the PVC nest jar housing the warbler nest. I removed the lid and began plucking the six-day-old nestlings from their sanctuary and gently placing them in a cloth bag. I recorded five sequential band numbers in my data book before I used my banding pliers to open each aluminum band so I could close it around a nestling’s leg. Once banded, I transferred each nestling with its new bracelet back to its nest.
The parents actively flitted around us in the brush and willows, and several times, I stopped banding so Skip could shoot footage of scurrying adults carrying inchworms in their bills. You would expect the birds to be aggressive and/or defensive as a large primate handled their young, but we were in for a big surprise. Once all of the nestlings were snug in their nest, I secured the jar’s lid and slid the sleeve up until the nest was only three feet above our heads. As I was fastening the sleeve to its mounting pipe, the unexpected happened: the male landed at his jar’s entrance and dipped into the nest chamber to deliver caterpillars that he had been impatiently carrying in his bill. He flew back out within a minute, only to make room for the female who repeated the same behavior. Apparently, the parents had feeding to do and were not about to allow intruders to interfere with their duties. Weird. As we waded back to our vehicles, I was chuckling about how compulsive the warbler parents had been, but they had also convinced us that our visit had done no harm.
The Alum Creek Prothonotary Warbler Project consists of 35 nest structures, standing singly or paired, at 26 over-the-water locations in the northern region of Alum Creek State Park south of Kilbourne, a small village on State Route 521 in Delaware County, Ohio. Since PVC nest jars heat up when exposed to the sun, I mount them along the western shores where they are shaded for all, or most, of the day. I access this water nestbox trail from Hogback Road, where raptor watchers and photographers gather daily to spy on four Osprey platforms that have raised 32 fish hawks over the lake since 2001. I try to launch my canoe in the early morning hours before the warming sun generates convection currents that turn into wind on the lake. I use a Kayak paddle to propel my extra wide 12-foot Old Towne Stillwater canoe directly to the most southern nest jar along the western lakeshore before I work my way back north. I inspect each nest chamber along the shoreline for seven-tenths of a mile before I reach the mouth of the stream. I continue up stream for one mile before I reach the other end of the project. After I check all nest jars and boxes, including boxes located along several auxiliary streams, my monitoring takes four hours and covers four miles before I return to the guardrail at Hogback Road.
Between May 3 and July 24, I monitored the Alum Creek water trail during a dozen fun-filled trips, escorted by Kingfishers and Rough-winged swallows that nest in the shale and clay cliffs overlooking the water. The quest to attach U.S. Fish and Wildlife aluminum leg bands to all nestlings requires extra canoe launchings. Prothonotaries fledge within eleven days after hatching and I prefer to band warbler nestlings when they are five or six days old, and in order to meet the goal of banding all families, the narrow window of opportunity requires vigilant monitoring, precise record keeping, and accurate extrapolations.
The 2009 Prothonotary Warbler season, from the first egg to the last fledgling, lasted from May 13 through July 20, a 69-day period that did not count the earliest date when male warblers arrived to claim nestboxes with moss deposits. I found the first down payments of moss on May 3.
During their season, male Prothonotaries added moss at 15 locations (57.7%), and females completed nests at seven locations (26.9%), or using the same numbers, females completed 46.7% of the nests started by males. Eggs were laid in six nests, the same as 2008, and four (66.7%) of those nests successfully fledged 17 warblers. Sticks deposited on top of two warbler nests left no doubt that House Wrens were responsible for the failures.
Other native species took advantage of nestboxes at Alum Creek. Tree Swallows claimed nine jars to fledge 29. House Wrens fledged 28 from five nests while Carolina Chickadees claimed four nestboxes to add 19 young to Alum Creek’s ecosystem. All chickadee nests were found near the creek’s mouth and fit within a circle that is 400 yards wide, a very amazing concentration of successful nests.
Prothonotary Warblers made July 2 a very exciting day for me. I had calculated that three nestlings were going to fledge from Jar No. 16 on July 1, so on July 2, I slid my canoe alongside the jar’s pole, snapped a rope around it, and went about lowering the nest. I was shocked to discover that the olive-green nestlings were still inside. Even though I don’t like to disturb a family that is due to fledge, I could not resist taking a picture. I was very pleased to return the jar to its original position without any of the nestlings making a break for it.
After my supper that very day, I followed a routine of reporting to Hogback Road to watch Osprey. My objective was to spy on four Osprey nestlings and their mother on Platform No. Four. This was our largest family since Ospreys started nesting in Delaware County in 2001. Photographers had trimmed a tunnel in the foliage on top of the cliff that overlooked the nest. I set up my equipment near the cliff’s edge and soon concluded that all was well with the fish hawks. Then, I turned my spotting scope twenty degrees north to see if anything was going on with Nest Jar No. 16 that is one thousand feet across the lake. With my scope set at 35x, I could recognize a nestling perched in the jar’s entrance. It started beating its wings, only to fall forward and ended up hanging by its feet. It’s wings never stopped as it righted itself to disappear back into the nest chamber. I laughed out loud, but I had to admit that the clumsy maneuver was not bad for a creature that eleven days earlier was a naked fetus chipping its way out of an egg.
Within seconds, a nestling reappeared at the jar’s doorway as an adult warbler flew back and forth between two limbs, apparently encouraging the feathered novice to go for it. At 19:41, a fledgling was born as the young warbler flew in an upward arc to land in the Oak tree above its nest. Ten minutes later, I was still glued to my spotting scope as a second fledgling followed the same aerial path into the oak tree. Everything else that evening was anticlimactic.
The golden swamp warblers never failed to inspire me as I monitored their nestboxes. Most times when I heard male prothonotaries singing, I could not see them, but when I did, they looked like yellow and green Christmas ornaments. Even though I did not raise as many warblers as I had hoped, I was pleased when they expanded their historic nesting zone south along the lakeshore. All nestboxes and jars are now in storage until next spring when I will try some new management strategies, if I am able. Meanwhile, perhaps a researcher somewhere will read a leg band on a live bird and we’ll learn more about the “school bus yellow” warblers from Delaware County.