What to look for in nature in Delaware this May

When do horseshoe crabs spawn at their peak on Delaware Bay?

• The spawning peak

  Mostly May, strongest on the high tides near the new moon (May 6) and the full moon (May 20) · Bay beaches of Kent County: Slaughter Beach, Kitts Hummock, Pickering Beach, Bowers Beach, Woodland Beach and Mispillion Harbor

  The crabs come in on the rising tide, and they are most active on the beach after dark. The state’s DuPont Nature Center page says any high tide from May into early June can bring crabs, and that the biggest nights tend to follow the new and full moon tides. The nature center’s page points to NOAA’s tide predictions, so look up the hour for the bay shore and arrive early. Step carefully on the upper beach, because the eggs are laid in the sand.

• Watching without harming

  Any spawning tide · Beaches with public access

  Central Delaware’s tourism office suggests a red flashlight for night watching, because red light bothers wildlife less than white. A crab stuck upside down can be righted by tipping it over at the edge of its shell; the tail is never a handle. The same page says to keep noise down, step carefully and bring binoculars, so that you do not scare off feeding birds. Check each community’s beach rules before you go.

• A guided evening on the tide

  Saturday, May 22, 2027, 2 to 6 p.m. · DuPont Nature Center, Milford, then Slaughter Beach

  The society’s calendar lists “High Tide, Horseshoe Crabs and Happy Hour with Anthony Gonzon” on that date, timed to the rising high tide during peak spawning and shorebird migration. The group will bird around the Nature Center and then drive to Slaughter Beach. The page we saw did not give a price or registration rules, so look at the society’s event page before you go.

Which shorebirds are on the Delaware Bay beaches in May, and for how long?

• Red knots

  Mid-May to early June · Mispillion Harbor, Slaughter Beach and the Kent County beaches

  Red knots are the bird that made this beach famous, and the state’s biologists say more than half of the Western Hemisphere’s red knots may be in Delaware Bay in May. More than 90 percent of their diet here is horseshoe crab eggs, and the weight they put on in about two weeks carries them on a nonstop flight to their Arctic breeding grounds and helps them through the first days of nesting. The state’s shorebird program notes that nearly 100,000 knots once stopped in the bay and about 40,000 did in 2019. Look for a robin-sized, brick-red bird in a close flock with its bill probing the wet sand.

• Turnstones, sandpipers and sanderlings

  Mid-May to early June · Same beaches, plus the Mispillion Harbor flats

  Ruddy turnstones, with their calico backs, flip stones and seaweed in the wrack line, and sanderlings run at the edge of the waves. The smaller semipalmated sandpipers and dunlins pack in tight flocks. Many are in breeding plumage by May, which makes identification easier than in the fall. The Delaware Ornithological Society recommends the DuPont Nature Center, Bombay Hook and Cape Henlopen for the shorebird peak.

• A viewing code

  All of May · Any beach where birds are feeding

  The state asks the public to stay at least 400 feet from flocks, to respect fenced and closed areas, to keep dogs leashed and away from feeding birds, and not to feed gulls. A disturbed flock burns fuel the birds need for the Arctic. The DuPont Nature Center’s deck above Mispillion Harbor stays open daily from dawn until dusk, even when the building is shut, and the Center itself was listed as open Tuesday through Saturday from 9 a.m. to 4 p.m. in May on the page we read. Confirm the 2027 hours before you drive.

When does the warbler migration peak in Delaware?

• Where to find them

  The first three weeks of May · White Clay Creek State Park in the north (a society walk was held there one May); Bombay Hook’s wooded edges; the Nanticoke River forests in Sussex County

  Look for warblers in the canopy of oaks and tulip trees in the morning, when they feed hardest. A society field trip in a past spring went to the Nanticoke Wildlife Area for newly arrived songbirds such as prothonotary warblers, vireos and tanagers, which suggests that the river swamps of western Sussex are a good bet for that golden warbler, though that was a single trip report.

• How to practice

  Early morning · Any wooded park

  Stand still under a flowering tree for ten minutes and listen before you look. The eBird bar charts for Delaware, which the society recommends, show when each species is most common, so you can see which warblers are likely in the second week and which come only at the end of the month.

• Count days and dates to check

  Check with the organizers · Online and in the field

  World Migratory Bird Day is held on two dates a year, and the organizers’ page lists May 9 and October 10 for 2026 but had not posted 2027 dates when we read it. Cornell’s Global Big Day, a one-day worldwide bird count, also falls in May, and Cornell announces its date each year. The Delaware Ornithological Society holds a spring Bird-a-Thon fundraiser in early May in some years, so look at its calendar rather than relying on this page for a date.

What is nesting on Delaware’s beaches in May?

• Piping plover chicks

  Nesting under way; chicks hatch and fledge into the summer · The Point at Cape Henlopen State Park and Fowler Beach in Prime Hook National Wildlife Refuge

  Delaware’s plovers arrive in March, and the state counted 30 breeding pairs in 2025. That year Fowler Beach had 18 fledglings from 21 pairs, and The Point had nine fledglings from nine pairs, for a statewide 0.90 fledglings per pair against a goal of 1.5. The state’s plover page names predators, May storms and June heat among the causes of the low result. Chicks are tiny and sand-colored, which is why the closures matter.

• Least terns arrive

  May or June · Fowler Beach and The Point

  The state says least terns typically reach the beaches in May or June and head south by September. In 2025 Fowler Beach had 92 breeding pairs out of a statewide total of 127, and The Point held about 35. Colonies are sometimes ringed with electric fence against red foxes. If terns hover and dive at your head, you are too close to a colony.

• American oystercatchers

  Nesting since April · Fowler Beach, the Inland Bays marshes and the ocean beaches

  These black-and-white birds with orange bills nest on bare sand and in salt marsh. DNREC counted 11 breeding pairs in 2025 and five fledglings, all of them from the Inland Bays rather than the ocean beaches. If you see one with dark green leg bands starting with the letter F, the state asks that you report it.

• The Point is closed

  Through the summer · Cape Henlopen State Park

  Delaware Public Radio reported that the closure at The Point began on March 1 in 2026, with the ocean-side beach reopening on September 1 and the bayside beach on October 1. We expect a similar schedule in 2027, but the park can change the dates, so check with the park. The dunes are off limits all year.

Where can you see Delaware’s heron and egret colony?

• A colony on an island

  Nesting season, spring into summer · Pea Patch Island, reached by ferry from Delaware City

  A society field trip in 2026 started at the ferry dock at 45 Clinton Street in Delaware City. Tickets come from Delaware State Parks, and the fare includes admission to Fort Delaware, the Civil War fort on the island. The group viewed the heronry from a new viewing platform. The state’s ferry season and 2027 dates were not available to us, so check Delaware State Parks before planning a trip.

• Young eagles

  June · Bombay Hook, Prime Hook, the Nanticoke River and the DuPont Nature Center

  Bombay Hook’s calendar lists baby eagles leaving the nest in June, so the young are growing in the big stick nests through May. DNREC names the same places as good spots to see eagles, and asks the public to report nests through its website.

When are fawns, ducklings, baby turtles and bats born in Delaware?

• Fawns

  Most are born from the last week of May through the first week of June · Fields, woodland edges and suburban yards statewide

  In a 2017 release, DNREC’s deer biologist said that even if a fawn appears to be alone, its mother is likely close by, coming back only to feed it so that she does not draw predators. A fawn lying still in the grass is hiding, not lost. The Chesapeake Bay Program’s field guide says fawns can walk at birth, are spotted, and lie very still when the doe is away. In Delaware it is illegal to possess or try to raise a live deer or other native wildlife without a state permit. If you are worried, call DNREC’s Division of Fish and Wildlife at 302-735-3600.

• Diamondback terrapins

  Females come ashore from late May through July · Port Mahon Road near Little Creek, and Route 1 along the coast in June and July

  The state says female terrapins leave the bay for sandy, bare roadsides to nest, and that Port Mahon Road in Kent County is a hot spot. DNREC has asked volunteers to help turtles around the rocks along that road during nesting shifts tied to high tide. On the coast, the Center for the Inland Bays says to watch for terrapins on Route 1 in June and July, and to carry any you move to the bay side of the fence, holding the shell by its sides.

• Bats and their pups

  Pups born from about mid-May · Barns, attics and woodland roosts

  DNREC says nine bat species live in Delaware, with the big brown and red bats the most common. A 2018 state release said to finish any exclusion of bats from a building before May 15, when females start giving birth, so that flightless young are not shut in; DNREC’s current page simply points to the Division of Fish and Wildlife (302-735-3600) or a permitted wildlife control company. Check with the Division of Fish and Wildlife before you do anything: the little brown, tricolored and northern long-eared bats are on the state endangered list. DNREC adds that all known little brown bat colonies have disappeared since white-nose syndrome arrived.

What is in bloom and calling in a Delaware May?

• Tulip trees in flower

  May · Piedmont woods, Kent County hedgerows and Sussex County swamp edges

  The tall, straight tulip tree is the state’s most striking May bloomer. Its tulip-shaped, green-and-orange flowers sit high in the crown, so you will often find the fallen petals on the trail before you spot the blossoms.

• The deeper chorus

  May evenings · Ponds, mill ponds and swamp edges

  Green frogs make a banjo-string twang, and bullfrogs a deep, repeated drone. Both are summer voices in this part of the country, and the state’s calendar has them joining the chorus in May. Warm, damp nights are best.

• Baldcypress in fresh leaf

  May · Trap Pond State Park and the Great Cypress Swamp, Sussex County

  Trap Pond is home to the nation’s northernmost natural stand of baldcypress, according to the National Park Service. In spring the trees come into a fresh, airy green, and the knees stand up out of the dark water. DNREC suggests canoeing there, and the Great Cypress Swamp, held by Delaware Wild Lands, holds the largest freshwater wetland and block of forest in the state, with baldcypress, black tupelo and remnant Atlantic white cedar. Public access to the swamp is not described on the group’s page, so check before you visit.

• The first fireflies?

  Late May at the earliest · Lawns and meadow edges at dusk

  DNREC’s page on fireflies says the common eastern firefly is the species most often seen in Delaware, flashing a J-shape about every six seconds, and the state’s rare Bethany Beach firefly flashes from late June to early August. May is early, so treat a late-month flicker on a warm, humid evening as a bonus. Flashing begins roughly 35 minutes after sunset in the case of the Bethany Beach species.

What is May weather like in Delaware, and is a late freeze still possible?

How much daylight does Delaware gain in May?

What is in the night sky over Delaware in May 2027?

• The Eta Aquariids, a dark-sky year

  Mornings of May 5, 6 and 7, in the hours before dawn · Low in the east-southeast, with the radiant rising only an hour or two before the sky brightens

  The new moon falls on May 6, so no moonlight spoils the shower from Halley’s Comet. Published peak nights differ by a day (May 5 into 6 in one list, May 6 into 7 in Sea and Sky), so give yourself the three mornings from May 5 through 7. Rates are higher in the tropics; for Delaware, ten to thirty per hour is the optimistic end, and only from a dark site in the final stretch of night. Dawn’s first light (civil twilight) arrives at Dover at 5:29 a.m. on May 6, so set up around 4:30.

• The Flower Moon, a seasonal Blue Moon

  Full at 6:59 a.m. on Thursday, May 20; best on the evenings of May 19 and 20 · Rising in the east-southeast at Dover at 7:54 p.m. on May 19 and 8:58 p.m. on May 20

  The Moon, 99 percent lit on May 19, rises at Dover about 18 minutes before the 8:12 p.m. sunset. Counting from the March one, this spring has four full moons: the Worm Moon, the Pink Moon, this Flower Moon and the Strawberry Moon (the evening of June 18 in Delaware), and the older seasonal rule gives the name Blue Moon to the third of a four-moon season. Sea and Sky uses that rule here. Under the newer calendar-month rule, which wants two full moons in one month, 2027 has none.

• Mercury in the evening

  Best on the evenings of May 27 and 28; greatest elongation May 28 · Low in the west-northwest, roughly 45 to 90 minutes after sunset

  On May 28 the innermost planet stands farthest from the Sun in the evening sky, about 23 degrees, which makes late May the year’s finest dusk look at Mercury from the northern states. Dover’s sunset on May 27 is 8:19 p.m. and civil twilight ends at 8:50 p.m., so the planet should show between roughly 9:05 and 9:50 p.m. Find a clear northwest horizon. The time window is our own conversion, so allow a few minutes either way.

• Venus and Saturn at dawn

  Mornings of May 6, 7 and 8 · Very low in the east before sunrise

  Venus and Saturn come within roughly 0.6 degrees on May 7 (about a degree apart on the mornings either side). Venus lifts off the horizon barely an hour before sunrise, so both planets sit just a few degrees high in the glow of dawn; take binoculars and find a clean eastern horizon. Treat it as a bonus for early risers.

• Jupiter and the Moon

  Evening of May 12 · High in the southwest after dark

  A half Moon passes close to Jupiter on May 12; the nearest approach comes in the late afternoon, still daylight, so go out after dark and look for the bright pair high in the southwest, with Jupiter the steadier, whiter dot.

What can families do outdoors in Delaware in May 2027?

Safety notes for May in Delaware