By Rob Thorn
It was one of the iconic experiences of central Ohio birding. If you wanted to take visiting birders someplace that would shake up their conception of central Ohio, your choices were Clear Creek Metro Park, Highbanks, or the Hoover Boardwalk. Then the boardwalk suffered ice damage and was closed back in 2022. Deemed un-repairable, it was torn down 2 years ago, and work started on a replacement. Now it’s re-built and open, with a new redesign that should make it a go-to destination for decades to come.
Hoover Reservoir has always been a popular birding destination since it was filled in the 1950s, but it has two different “personalities.” The lower 2/3 is relatively deep, like many reservoirs, but the upper end is very shallow. As a source of Columbus water, it fills with winter and spring rains, but loses water in the summer and fall. The drop in level exposes extensive mudflats around the northern end. Add in the fact that you sit at the end of two sizeable streams– Big Walnut and Little Walnut – that bring a big load of silt into the upper reservoir, and you get an unusual situation: an inland river delta that gets a fresh layer of nutrient-laden mud every year.
The old boardwalk, opened in 2002, got you out into the heart of this delta. During the high-water period in spring and early summer, these rich shallows act as a nursery for algae, water plants, and larval insects that create a thriving aquatic food web that feeds large squads of minnows, shad, and juvenile bluegill. These feed larger fish that attract lots of fish-eating birds like cormorants, herons, eagles, and ospreys. You could go out to the boardwalk even in summer and expect a good showing of these fish-eating birds, along with nesting swallows, blackbirds, and warblers attracted by the insects hatching from the water.
The boardwalk parallels the channel of Little Walnut Creek, and offers great views of the small bays along the creek, which can harbor shorebirds and herons. The deeper water of the old creek hides bigger fish, and it’s favored by fishermen and fish-eating waterbirds like grebes, mergansers, and cormorants. Out near the mouth of the creek, the boardwalk brushes up against a swamp forest that can have woodpeckers, flycatchers, and colorful Prothonotary Warblers. Beyond that, it pokes out into the wider delta between the two creeks.
Out in this delta, as the water level drops over the summer, rich mud flats are exposed, allowing a whole different set of insects and plants to colonize it. Many insects and their larvae favor the wet mud near the retreating water line, and this creates perfect conditions for shorebirds. From July through October, flocks of migrant shorebirds like plovers, yellowlegs, dunlin, and sandpipers stop by on their migration south to feast on these insects, fueling up for their long journey. The Hoover Boardwalk was designed to stick you out by the edge of this fertile mudflat. The original version actually looped out over some of the mudflat, but the newer version just reaches the northern edge. However, it widens into a large platform with benches, perfect for long vigils at this productive spot.
The drier mud shoreward of the water’s edge develops a coating of small plants like shore grass, smartweed, and bidens. Because of the regular flooding and drying, larger plants like rushes, cattails and bushes cannot survive this zone, leaving it open for these opportunistic little plants. They grow, flower, and set seed quickly, and are often grazed by flocks of ducks and Canada Geese. These plants also host insects that attract insect-eating sparrows and flycatchers, as well as some unusual grass-loving shorebirds like American Golden Plovers and Baird’s and Buff-breasted Sandpipers. These grass-flats of upper Hoover Reservoir have become one of the best fall locations to search for these unusual shorebirds.