What to look for in nature in Indiana this May

When is the peak of warbler migration at the Indiana Dunes in May?

• A mid-May tower morning

  Early to mid-May, from first light · The Longshore Tower at Indiana Dunes State Park, and the woods near the West Lot

  Indiana Audubon's report from a five-hour watch on May 13, 2025, shows what a good morning looks like: 99 species and 1,081 individual birds, with 19 kinds of warblers including Cape May, Wilson's, Bay-breasted and Blackburnian. Tennessee Warblers sang in the treetops, a pair of cuckoos passed through, a late Rusty Blackbird called near the tower, and the counters noted that more warblers went unidentified than were named, a sign the warbler movement was near its crest. The wind turned from south to northeast during that watch, and the observers said it slowed the flow. One year is a single sample, so treat the second week of May as the likeliest stretch and let the weather decide.

• Birds that pass in the dark

  Overnight, during the same weeks · Over the tower and the dunes

  Many songbirds migrate at night and are heard rather than seen. During the 2025 festival, Indiana Audubon placed a microphone at the tower for the first time that year to record nocturnal flight calls, and it picked up Swainson's Thrush, Indigo Bunting, Yellow-billed Cuckoo and American Bittern, along with a state-endangered Barn Owl calling as it flew over. Thin, high notes overhead after dark in May are probably the flight itself.

• What stays to nest

  Late May onward · Throughout Indiana Dunes National Park

  More than 350 bird species have been confirmed at Indiana Dunes, the National Park Service says, which ranks the park among the top five for recorded species. Its 2014 to 2018 breeding bird surveys found Yellow Warbler, Common Yellowthroat, Gray Catbird, Red-eyed Vireo, Eastern Towhee and House Wren among the most common detections. These are survey detections, not nest counts.

• The Indiana Dunes Birding Festival

  Annual, in May; the National Park Service lists it as the third weekend of the month · Several sites around the Dunes

  Indiana Audubon hosts a four-day festival with expert-led outings, a youth and family birding day and a gear marketplace. Its website listed a 2026 schedule and nothing yet for 2027, so watch that site for dates, field trip sites and registration.

Which warblers and tanagers settle into Indiana's big forests in May?

• The songbird wave at Big Oaks

  Around the second week of May, per the refuge · Big Oaks National Wildlife Refuge, a roughly 50,000-acre Globally Important Bird Area

  The refuge reports that its main wave of songbirds peaks around the second week of May, and that white-tailed fawns are typically seen by the end of the month. A public access permit costs $3 a day or $15 a year, with some exemptions.

• Cerulean warblers in the canopy

  Males reach the nesting grounds around the middle of May · Tall, mature hardwood forest along streams and in river valleys

  The sky-blue back of a male Cerulean Warbler is hard to see because he sings from the top of the leafy canopy. Audubon's field guide describes the song as a series of short buzzy notes ending in a higher buzz, lists the species as threatened with strongly declining numbers, and notes that nests fail more often in small forest patches, where cowbirds are more abundant.

• Scarlet Tanagers in the oaks

  Mid to late May · Large blocks of oak woodland

  Audubon says Scarlet Tanagers cross the Gulf of Mexico at night and, after a cold snap, may feed in the open along roads and in gardens. The song is a hurried, burry, repetitive warble, somewhat like an American Robin's, and the call is an emphatic, nasal chip-bang. Males, the only brilliant red birds with black wings and tail, forage slowly in tall oaks.

• Prothonotary Warblers on the boardwalk

  Late spring and early summer, the nesting season · Indiana Dunes State Park, near the Trail 8 boardwalk, per the Indiana Birding Trail

  This golden warbler nests in tree cavities over standing water, usually 5 to 10 feet up, according to Audubon, and the Indiana Birding Trail names the boardwalk on Trail 8 as a known place for them. The same page lists Prairie and Hooded Warblers, Worm-eating Warblers and Summer Tanagers among the breeding birds, and says Barred Owls and Whip-poor-wills call on the trails after dark.

Where can I hear Henslow's sparrows and see prairie birds in Indiana in May?

• Henslow's sparrows at Big Oaks

  Spring and summer · The refuge's larger grasslands; a guided tour is the best way in

  The refuge reports more than 400 pairs of Henslow's Sparrow, which it calls one of the world's largest populations. The refuge says the birds sing in its larger grasslands in spring and summer, and that a guided bird tour is the best way to see one. Ask the refuge office about tour dates; the refuge site named none.

• Kankakee Sands

  Spring for migrants and early flowers; summer for the prairie in full color · The welcome area on U.S. 41; free and open daily, sunrise to sunset

  The Nature Conservancy describes 8,400 acres of restored prairie and wetland with more than 240 bird species recorded, including Henslow's Sparrow, Northern Harrier and Least Bittern, and it says the bison grazing keeps vegetation short enough to suit Upland Sandpipers. About 100 bison graze roughly 1,100 acres; stay out of the pasture and use the viewing area instead. The Meadowlark and Wet Prairie trails are closed while the bison are in the north pasture, so call the office on 219-285-2184 for current trail status.

Which frogs and toads call in Indiana in May?

• Fowler's toads

  Calling begins in late April or early May and runs into early July, per the Indiana Herp Atlas · Sandy open ground, floodplains and temporary pools, most common in the southern half and the northwestern sand prairies

  The call is a trill like the American Toad's but lower, nasal and harsher. Heavy rain filling a ditch or a field puddle can set off breeding at nearly any point in spring or early summer.

• Green frogs

  Males typically begin calling in May and breed sporadically through summer · Pond edges, creek pools and marshes

  The Herp Atlas likens the single low note to a loose banjo string plucked at irregular intervals, so it sounds more like an instrument than an animal.

• American bullfrogs

  Breeding runs from late May to early August · Permanent water only, because the tadpoles take one to three years to develop

  The deep, resonant "jug-o-rum" repeats at intervals of several minutes, and males defend territories by day and night. The Herp Atlas says one egg mass can hold up to 10,000 eggs.

What wildflowers bloom in Indiana in May?

• Mayapple and wild geranium

  Both open in early May, per the DNR brochure · Shaded woodland slopes in state parks

  Mayapples first appear like small umbrellas, with a waxy six-to-nine-petaled flower hidden beneath the big lobed leaves. Wild geranium opens in early May with five petals, and its name refers to a seed case shaped like a crane's bill.

• Wild columbine and Jack-in-the-pulpit

  Spring, into May · Rocky slopes and cliffs for columbine; wooded areas for Jack-in-the-pulpit

  Columbine's orange and yellow flowers hang from individual stalks and are pollinated by hummingbirds, moths and butterflies, according to the brochure. Jack-in-the-pulpit is easy to miss, a green hooded flower with a preacher inside, often with a single deeply divided leaf.

• Lupine and the lost Karner blue

  Late spring · Miller Woods and other sand ridges at Indiana Dunes National Park

  The National Park Service shows wild lupine growing on a vegetated sand ridge under oaks in Miller Woods and says it is the only food of Karner blue caterpillars. That butterfly is federally endangered, and a federal species page calls the Indiana Dunes population likely extirpated, so a lupine bloom here is a plant to admire, not a butterfly to expect. The Dunes shelter some 1,100 native vascular plants, among them the federally threatened Pitcher's thistle. Stay on marked trails in the savanna, since clearing and prescribed burns can weaken oaks and leave dead limbs overhead.

• Late-spring flowers at the Dunes

  Late spring · Trail 3 at Indiana Dunes State Park

  The state park's trail guide lists Trail 3 as a moderate three-quarter-mile walk for late-spring wildflowers, including prickly pear cactus. On the National Park Service side, the Heron Rookery Trail's wildflowers peak from late April through mid-May before the trees leaf out, and the herons that gave the trail its name have moved to new nesting grounds. Wild hyacinth in the Deam Wilderness blooms into early May.

What should I do if I find a fawn, a box turtle or a bat in May?

• Fawns

  Big Oaks says fawns are typically seen by the end of May · Fields and woodland edges statewide

  The DNR says fawns often hide alone and stay still for their first few weeks while the mother feeds, and asks people to leave them alone. Signs of trouble include a mother known to be dead, an obvious injury, many insects on the fawn or frequent crying. In LaGrange, Steuben, Noble, Allen, Whitley or DeKalb counties, a fawn can go only to a permitted rehabilitator in those same counties because of chronic wasting disease rules.

• Eastern box turtles

  Mating has been seen from late April through May and beyond · Woodlands, and unfortunately roads

  The DNR lists the eastern box turtle as a species of special concern, with slow maturity, few young and road deaths all hurting its numbers; individuals can live more than 60 years. On a busy road, the DNR says you may move one to the other side, still facing its original heading. Taking wild box turtles has been illegal since 2004, and nests should be left alone.

• Indiana bats

  They leave their caves and spread to summer roosts in spring; pups come in midsummer · Behind loose bark of trees near streams and rivers

  The DNR says females form maternity colonies of up to 100 bats and have a single pup in midsummer, which can fly within a month. White-nose syndrome has been found in 38 Indiana caves, and the DNR says the state's Indiana bat population has fallen 27 percent since it was first detected in 2010. The Forest Service's cave closure order for the Hoosier National Forest, which exists to protect hibernating bats, ends on May 14, so the caves open again on the 15th. If you find a sick or dead bat, report it and do not handle it.

What is May weather like in Indiana, and what should I watch for?

When is the last spring freeze in Indiana?

How much daylight does Indiana gain in May?

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

• The Eta Aquariid meteors, a good year

  Peak night May 5 to 6; try predawn on May 5, 6 and 7 · In the eastern sky before sunrise

  These meteors are grains shed by Halley's comet, and they trickle in from late April to late May. With the Moon a sliver on the 6th, the sky stays dark, and SeaSky rates 2027 an excellent year for the shower. The American Meteor Society puts typical rates at 10 to 30 per hour in the last stretch before dawn for observers from the equator northward. Indiana sits far enough north that the radiant, in Aquarius, comes up just one to two hours before the Sun, so the count here runs lower than in the Deep South.

• Moon, Jupiter and Mars

  Evenings of Wednesday, May 12 and Thursday, May 13 · In the south and southwest once the sky is dark

  Our own sky calculations put a half-lit Moon a little over a degree from Jupiter on May 12, with Jupiter high in the south after dark. One night later the Moon has slid east, to roughly three degrees from reddish Mars. Both are evening planets all month, and Jupiter should set roughly seven hours past sundown in early May. Treat those figures as calculated rather than published.

• Venus and Saturn at dawn

  Mornings around May 7 · Very low in the east, just before sunrise, with a flat horizon

  Our figures have the two planets about a degree apart on May 6 and again on May 8, and closest, at about six-tenths of a degree, during daylight on the 7th. Thirty minutes before sunrise both hang just a few degrees up. Bring binoculars and a flat eastern horizon, and treat it as a curiosity.

• The Flower Moon, a seasonal Blue Moon

  Full at 6:59 a.m. Eastern on Thursday, May 20 (5:59 a.m. Central); watch on the evening of May 19 · Rising low in the east around sunset

  Because the Moon turns full just before sunrise on the 20th, the evening of the 19th shows it at its roundest, rising about when the Sun sets. SeaSky labels it a Blue Moon for an older seasonal reason: it ranks third among the four full moons of astronomical spring. By the newer rule, which wants two full moons within one calendar month, no Blue Moon occurs from March to September. It is not a supermoon.

• Mercury at its best evening

  Widest at May 28; a good view from mid-May to early June · Low in the west-northwest, within about 45 to 90 minutes of sunset

  Mercury reaches its widest angle east of the Sun, 22.9 degrees per SeaSky, on May 28. For the northern United States it is the best evening appearance of the year, with the evenings of the 27th and 28th both close to the best. The 45-to-90-minute window is our own estimate, so allow extra time. Find an open western horizon and use binoculars as twilight fades.

• The Milky Way before dawn

  The first half of May and the last week · Low in the south in the small hours, from a dark site

  At 40 degrees north, our own arithmetic finds as much as 3.8 hours when the Moon is down, the sky is fully dark and the galactic core sits above the horizon. May through August are the best months for the Milky Way.

What can Indiana families do outdoors in May 2027?

Safety notes for May in Indiana