Exploring The Mispillion River

by Jim Rapp

Naturalist Jim Rapp organizer of the annual award-winning Delmarva Birding Weekend and director of the Hazel Outdoor Discovery Center in Eden, Maryland tells us about birding on the Mispillion River.

Watch slideshow:

Wild Turkey Pileated Woodpecker Louisiana Wood Thrush Cormorants Clapper Rail Red Knot Red Knots eating Horseshoe Crabs

To really get to know Delmarva, you must explore our rivers. We have thousands of miles of shoreline that can be experienced by boat, kayak, canoe and stand-up paddleboard. Many of our parks provide nature trails and boardwalks that bring you close to water and wildlife without getting your feet wet.

Delmarva rivers typically begin in swampy headwaters that drain our forests and fields. Headwater habitat supports animals that prefer shady forests and fresh water. As the river meanders and widens towards our more salty estuaries, the forests give way to the marsh and the animals that like the sand, mud and open water of the Chesapeake, Delaware and Atlantic Coastal Bays.

For birders and wildlife watchers, the diversity of river ecosystems provides incredible opportunities for exploring and studying nature. You can start your morning in the wet woods of the headwaters as the sun rises and the forest awakens, stop in one of our historic small towns for lunch, and finish your day along the marshy coast with the setting sun.

Exploring along the Mispillion River in Southern Delaware is a great way to spend a day, and will most certainly reward birders with an impressive species list. The river is about 15 miles long and defines the boundary between Sussex and Kent Counties. The Mispillion begins in Northern Sussex County and flows east/northeast through the lakes west of historic Milford, Delaware, before turning north and then east again towards its mouth at the Delaware Bay just north of Slaughter Beach.

The upper stretches of the Mispillion were once known as "the Saw Mill Range." Dams were built across these narrow sections of river to generate hydropower for sawmills and gristmills. Abbott's Mill, located just three miles southwest of Milford, started milling in 1795 and ceased operations in 1960. It was listed on the National Register of Historic Places in 1972, and is now managed by the Delaware Nature Society as part of the 313-acre Milford Millponds Nature Preserve.

Abbott's Mill is a great place to begin your Mispillion day trip. Three miles of hiking trails and a streamside boardwalk are open from dawn to dusk, so you can arrive shortly after sunrise to hike while surrounded by morning bird song. There's also canoe and kayak access if you want to experience sunrise on the water.

More than 160 species of birds have been recorded in the Nature Preserve. You are likely to see Wild Turkeys and Pileated Woodpeckers year-round, and migratory songbirds in the spring.

One of the early spring migrants you may see or hear at Abbott's Mill in late April is the Louisiana Waterthrush. This large warbler can be found foraging for insects, worms and even small frogs and fish under the cover of branches at the water's edge. While flipping over leaves in search of food, it constantly bobs its tail up and down.

The Louisiana Waterthrush looks more like a thrush or sparrow than a warbler. It has a brown back, white belly with brown stripes, and a white stripe over its eyes. After a morning of activity, the Louisiana Waterthrush may nap in the afternoon. If you have really keen spotting skills, you may find a napping bird perched with its eyes closed, and its neck and legs pulled close to its body.

After touring the preserve around Abbott's Mill, head into Milford for lunch and a walk along the Mispillion Riverwalk. This greenway along the town's historic waterfront once hosted seven bustling shipyards, and is a good spot to add a Double-crested Cormorant or Chimney Swift to your species list for the day.

After lunch, head east on Route 36 for about six miles and make a left at Lighthouse Road. Stop along the road and look north into the expansive marsh. The Mispillion is now just a few hundred yards away, flowing towards its finish at the Delaware Bayshore. Seaside Sparrows and Clapper Rails can be found hidden in the grass of the marsh along the Mispillion, the same river that just ten miles west supported forest-loving warblers and woodpeckers.

Perched along the bay at the end of Lighthouse Road, you'll spot the distinctive red roof of the DuPont Nature Center at Mispillion Harbor Reserve. This one-of-a kind site is managed by the Delaware Division of Fish & Wildlife, and includes an interpretive center and observation deck with telescopes to view the Delaware Bay shoreline. The center features exhibits about the ecological relationship between migrating shorebirds and the horseshoe crabs that lay their eggs on the Bay's beaches.

Delaware Bay is a major fueling stop for shorebirds that travel thousands of miles from their South American wintering grounds to breed in the Canadian Arctic. The birds gorge themselves on protein-rich horseshoe crab eggs, and can double their weight after a week or so feeding along the Delaware Bay. One shorebird with a critical dependence on horseshoe crab eggs to continue their journey north is the Red Knot.

The Atlantic Flyway subspecies of the Red Knot has experienced more than a 75% decline since the 1980s due primarily to an increase in the commercial harvest of horseshoe crabs. In 2014, the Atlantic Flyway Red Knot was listed as threatened under the federal Endangered Species Act. Nearly 90% of the entire world's population of Atlantic Flyway Red Knots can be present along the Delaware Bay in a single day!

One of the longest-distance migrants in the animal kingdom, the Atlantic Flyway Red Knot travels over 18,000 miles round-trip every year. These large and colorful shorebirds can be found mixed in with Semi-palmated Sandpipers and Ruddy Turnstones feeding in the sand and mud between the gently lapping waves of the bay. Breeding male Red Knots are easy to pick out of the flock with their red heads and breasts and salt and pepper-colored backs.

This amazing wildlife spectacle is unique to the Delaware Bayshore and is best witnessed right here at Mispillion Harbor and Slaughter Beach. A good time to observe horseshoe crab spawning and the shorebird feeding frenzy is near the full and new moons of May and early June. During the day following a high-tide horseshoe crab spawn, you will be amazed at the thousands upon thousands of shorebirds gorging themselves on the tiny green eggs.

After your time birding along the mouth of the Mispillion at the Delaware Bayshore, you can end your day with a great meal at one of Milford's fine restaurants, and take in a Delmarva sunset with a twilight stroll along the historic riverfront.