What to look for in nature in Wyoming this May

When are elk, pronghorn and moose calves and fawns born in Wyoming, and how close can you go?

• Bison calving reaches its peak

  May; the Yellowstone herd calves from late April · Lamar and Hayden valleys and the Madison corridor, Yellowstone

  Teton Science Schools’ wildlife calendar says bison usually hit the peak of calving in May, earlier than most hooved animals, and the National Park Service puts Yellowstone’s calf arrivals between late April and May. Calves are reddish tan at first, so a scan of a herd for small orange shapes beside the dark cows pays off. Visitors are asked to stay 25 yards or more from bison.

• Elk calves arrive from May into late June

  May to late June, with the exact timing set by green-up · Elk summer range in Yellowstone, the Tetons and the Bighorn and Wind River mountains

  The park service says a single elk calf is born from May to late June, timed to coincide with the most nutritious plant growth. Migratory cows leave the winter range when snow melts and the grass greens up, so a late spring delays them and an early one pulls them uphill sooner. The same page warns that newborn calves are vulnerable, and that bears, mountain lions and other predators depend on elk, so a calf’s first weeks are a risky time.

• Pronghorn and deer fawns, and the moose calf

  Born in May and into June · Open sagebrush, river bottoms and willow thickets; Seedskadee National Wildlife Refuge is one good place

  Seedskadee National Wildlife Refuge says pronghorn fawns, mule deer and white-tailed deer fawns and moose calves are all born there in May and into June. Yellowstone’s page on mule deer gives late May to early August for fawns. Before a moose cow calves she drives off last year’s young and seeks out a thicket, says Grand Teton National Park, and the calf weighs only about 25 to 35 pounds yet walks within hours. The park calls cows with calves unpredictable, noting that they have chased people.

• One long pronghorn commute

  Spring, as the snow lets go · Between the upper Green River basin and Grand Teton National Park

  Teton Science Schools describes a western Wyoming pronghorn herd that travels about 100 miles south to the upper Green River basin each autumn and returns the following spring along the same corridor. Other pronghorn populations in the state move far less, from 5 to 30 miles or not at all. A pronghorn doe on the sagebrush flats in late May may be either a long-distance traveler or a homebody that never left.

• Let the young animals be

  All of May and June · Anywhere newborns are on the ground

  Teton Science Schools says many young hooved animals are orange, a camouflage that works because most mammal predators are red-green color blind, and that nearly all hooved animals reach the peak of birthing in June. A newborn’s best protection is not being noticed, so take your picture from a distance and move on. The park’s rules are 25 yards from elk and other hooved animals and a much larger 100 yards away from any bear, wolf or cougar.

Can you pick up shed antlers in Wyoming in May, and are bighorn lambs out?

• Shed antler season west of the Continental Divide

  Closed January 1 until early May; confirm the current dates · Public land west of the Divide, including national forest, BLM and state land

  Game and Fish’s notices show the winter closure ending at 6 a.m. on May 1 each year. A January 2024 notice listed residents at May 1 and nonresidents at May 8, while a January 2023 notice gave May 1 without that split. The rules may have changed since, so check the department’s page for the current dates and map. The closure also includes searching for or possessing shed antlers during the closed period, and you need the owner’s permission to enter private land at any time. Violations can cost fines, the antlers and hunting and fishing privileges.

• New antlers are already growing

  Bulls start in April or May; growth ends around August · Elk, moose and mule deer on their spring range

  Yellowstone says most of its bulls lose their antlers in March or April and then regrow a new set, over about 90 days for yearlings and up to about 140 days for healthy mature bulls. Velvet-covered knobs show up on moose in April or May according to Grand Teton, and mule deer bucks begin in April or May and keep going until August or September. Look for the fuzzy, swollen tines on a summer-range bull at a distance.

• Bighorn lambs in the canyon country

  Lambs arrive in May or June · Gardner Canyon, Dunraven Pass and Mount Washburn in Yellowstone; Whiskey Basin near Dubois

  Yellowstone says its bighorn ewes lamb in May or June, with one or two lambs each, and most sheep move to higher ground between May and October. Game and Fish says the Whiskey Mountain herd near Dubois numbers about 750 now, down from an estimated 2,500, with poor lamb survival that it thinks is due to lamb pneumonia. Watch lambs from a distance and use binoculars.

What are Yellowstone’s wolves and grizzlies doing in May?

• Wolf dens come alive

  Pups born in mid-April, by the park’s account; dens stay busy for weeks · Northern range and Lamar Valley, Yellowstone

  Yellowstone’s wolf page says the average litter is five pups born in mid-April, that pups come above ground at 10 to 14 days of age and that a pack may stay at its den for three to ten weeks unless disturbed. Wolf numbers in the park have generally fluctuated between 83 and 123 since 2009, per the same page. It calls the northern range one of the best places in the world to watch wolves, and they are most active at dawn and dusk. Bring a spotting scope, park only in pullouts and stay 100 yards from any wolf that comes near.

• Grizzlies and black bears are on the move

  Spring, with sightings that peak in April by Teton Science Schools’ account · Open meadows, burn slopes and the road corridors of Yellowstone and Grand Teton

  Game and Fish’s spring notice tells people that bears have left their dens and gives the usual advice: keep garbage, pet food and birdseed out of reach, and carry bear spray that you can grab quickly. A grizzly will defend a carcass, so avoid any place with a carcass or a gathering of scavenging birds. Yellowstone adds that 91 percent of the people hurt by its bears were alone or in a party of two, and recommends groups of three or more, making noise and hiking in daylight.

• Hunting and fishing in bear country

  Spring black bear and turkey seasons · National forest and public land

  Game and Fish’s hunting advice includes hunting with a partner, learning to read tracks, scat and digging, and knowing where seasonal food is. It advises hanging quartered meat 10 to 15 feet off the ground, hauling out meat quickly and keeping a gut pile well away. Fish should be cleaned at a station or at home. Wyoming’s spring black bear seasons are set in Chapter 3 of its regulations, and they differ by area, so check the latest edition before heading out.

Which birds are passing through Wyoming in May, from warblers to harlequin ducks?

• Warblers in the cottonwoods

  May · Seedskadee National Wildlife Refuge, from headquarters to the base of Fontenelle Dam

  The refuge says secretive warblers arrive in May to rest and feed on insects in the new leaves of narrowleaf cottonwood, some from as far away as southern South America. The stretch between the headquarters and the base of Fontenelle Dam is one of Wyoming’s best places to see them in spring. The refuge also says birding is usually good along the river, and that wildlife viewing is best in the early morning or late evening.

• Harlequin ducks on whitewater

  A short visit, usually in May · Fast rivers in Yellowstone, such as Soda Butte Creek and LeHardy Rapids

  Teton Science Schools’ calendar says harlequin ducks make a brief visit, arriving from Pacific winter homes to feed and court in whitewater before they leave for the year. A Yellowstone Forever field note reports harlequins, yellow warblers, redheads, eared grebes, northern shovelers, lesser yellowlegs and yellow-headed blackbirds all appearing for the first time in one mid-May week.

• Lakes, shorebirds and migrant traps

  Shorebirds peak from April into mid-May; songbirds through the month · Hutton Lake near Laramie, Keyhole State Park, Edness Kimball Wilkins State Park, Lions Park and the Wyoming Hereford Ranch in the southeast

  Audubon’s Wyoming birding guide singles out several places. Hutton Lake National Wildlife Refuge has logged nearly 30 shorebird species across spring and fall and more than 15 duck species in migration. Keyhole and Edness Kimball Wilkins draw ducks, loons, grebes, gulls, terns and shorebirds, and Cheyenne’s Lions Park and its Sloan Lake are described as a migrant oasis in spring. The Seedskadee page says shorebird passage runs from early April through mid-May, so late May belongs to the songbirds.

• Meadowlarks are on their nests

  Males sing in late April and early May to attract mates · Open grassland statewide

  A Game and Fish article calls the western meadowlark’s song an introductory declaration of Wyoming’s spring. The female builds in a ground depression and lays about five eggs, with the parents sharing feeding duties. Walk grassland edges slowly in May and you may flush one off a nest; step back the way you came.

Who is nesting in Wyoming in May: cranes, pelicans, swans, owls and falcons?

• Sandhill cranes and white pelicans in Yellowstone

  Nesting through the early summer; about 150 species nest in the park · Hayden Valley for cranes; the Molly Islands, in the southeast arm of Yellowstone Lake, for pelicans

  The park service says sandhill cranes nest in Yellowstone in summer, often in Hayden Valley, and that American white pelicans nest mainly on the Molly Islands. It suggests early morning walks from mid-May through early July. Pelicans can also be seen cruising the Yellowstone River in Hayden Valley.

• Trumpeter swans on the water

  Pairs sit on eggs in May; cygnets start hatching around mid-June at Seedskadee · Green River basin, Seedskadee, Yellowstone and Grand Teton

  Game and Fish flies three aerial surveys of western Wyoming swans, in May, July and September, counting occupied nests, hatchlings and survivors. The 2016 survey found 68 percent of the state’s adults nesting in the Green River basin, where swans were absent in the early 1990s. Audubon says eggs hatch in 32 to 37 days and clutches are usually four to six, so a May nest is almost always still on eggs. Keep your distance from nest sites.

• Burrowing owls move into the prairie dog towns

  Eggs and young in late spring and early summer · Eastern Wyoming grasslands, most abundantly

  Game and Fish says burrowing owls nest underground, often in tunnels excavated by prairie dogs or ground squirrels, and that females lay 6 to 12 eggs on average with incubation of about 28 to 30 days. The agency calls them most abundant in eastern grasslands. Watch from your vehicle and let the birds decide how close the encounter will be.

• Prairie falcons and swifts on the Tower

  Nesting season; call for dates · Devils Tower National Monument

  The park’s bird checklist marks the prairie falcon and white-throated swift as breeding species, and Audubon points birders to the Tower for nesting prairie falcons. The checklist does not give nesting dates, so call the monument at 307-467-5283 extension 635 before you plan a trip around them.

Is the Wyoming toad out yet, and what is blooming at the snowline in May?

• The Wyoming toad wakes up

  Adults emerge in May or June, once daytime highs reach 70 °F; eggs from mid-May to early June · Mortenson Lake National Wildlife Refuge, closed to the public

  The Fish and Wildlife Service says adults come out of hibernation in May or June after daytime highs reach 70 degrees Fahrenheit, that males call to draw females and that eggs are laid in gelatinous strings between mid-May and early June. The agency’s refuge page says Mortenson Lake is closed to public use to avoid harming the toad and points visitors to public access areas nearby, such as Meeboer Lake, Gelatt Lake and Twin Buttes. In 2023 the Service and partners acquired 1,078 acres near Hutton Lake for a Wyoming Toad Conservation Area.

• Buttercups, turkey peas and yellow bells

  Early flowers open as the snow retreats; yellow bells show up in late-spring lists · Gravelly slopes at the snowline, Jackson Hole

  A Teton Science Schools post written in mid-May describes sagebrush buttercup, turkey peas and steer’s head as some of the first blossoms to appear in the sagebrush as snow melts, on rocky soil at the snowline. Yellow bells are on the same author’s list of late-spring sightings. Mountain flowers bloom later at each step uphill, so a hike up a drainage in May can show spring, early summer and leftover snow in a few hours.

• The state’s native plant society meets late in May

  Usually the end of May; 2027 plans not posted · A different part of the state each year

  The Wyoming Native Plant Society’s 2026 annual meeting and Wildflower Weekend ran May 29 to 31 at Firehole Canyon Campground near Flaming Gorge, with guided hikes and registration due May 19. The society’s page had nothing about 2027, so watch wynps.org for the next announcement.

When is the last spring freeze in Wyoming?

How warm, wet and stormy is May in Wyoming?

How fast do the days lengthen in Wyoming in May?

What can you see in Wyoming’s night sky in May 2027?

• The Eta Aquariids, a very good year

  Active about April 19 to May 28; best mornings May 5, 6 and 7 before dawn · Low in the east, toward dawn, away from town lights

  The American Meteor Society’s calendar lists the shower’s peak as the night of May 5 into May 6, with almost no moonlight in the way because the moon is a 2 percent sliver and the new moon arrives on May 6. The tropics see the strongest show. The society’s figure for northern skies is 10 to 30 meteors every hour, counted in the final dark stretch ahead of sunrise, and good activity lasts about a week around the peak. Wyoming is near the northern edge, and Aquarius, the constellation the meteors seem to spring from, clears the horizon only shortly before sunrise here, so expect fewer. Dress warmly and lie back facing east.

• The Flower Moon, a seasonal Blue Moon

  Full at 4:59 a.m. MDT on Thursday, May 20; look the evening of Wednesday, May 19 · Any clear eastern horizon after sunset

  The moon is full in the early morning, so it looks full both the evening before and the evening after. By our calculations moonrise on May 19 falls near 8 p.m. in the southern part of the state, a little later farther north. May’s full moon is commonly called the Flower Moon. Four full moons crowd into the span between spring’s first day and summer’s, and an old almanac convention calls the third full moon in a season of four the Blue Moon. By that count May 20 qualifies; by the more familiar two-in-a-month count, no month of 2027 does.

• Mercury at its best evening

  Greatest elongation Friday, May 28; look May 12 to June 5, and especially May 27 and 28 · Low in the west-northwest, 45 to 90 minutes after sunset

  On May 28 Mercury reaches its farthest point from the Sun in the evening sky, roughly 23 degrees out; Thursday and Friday, May 27 and 28, give the best chances. By our calculations it sets barely 20 minutes behind the Sun early in the month, that lag has grown past 90 minutes by mid-month, and in June it dims rapidly. Seek an open western horizon and start looking while the sky is still fading.

• Jupiter, Mars and the first-quarter moon

  Evenings of May 12 and 13 · High in the south-southwest after dusk

  The first-quarter moon stands close to bright Jupiter on May 12, about 1 degree apart, and sits near Mars, roughly 3 degrees away, on May 13. Jupiter is easy to spot by its steady glare, while Mars is a modest, orange-tinted point.

• Venus meets Saturn before dawn

  Morning of Friday, May 7; also nearby mornings · Low in the east before sunrise

  On May 7 Venus passes just 0.6 degrees from Saturn. Both hug the eastern horizon, with Venus rising barely an hour before sunrise, so go out early with binoculars and a clear view. Saturn is far fainter than its bright neighbor.

• Milky Way season is opening

  May 1 to 14 and May 25 to 31 near 40 degrees north; fewer hours in the north · Dark sites with a clear southern horizon, before dawn

  The galactic center, in Sagittarius, sits low in the south and only clears the ridgelines in the small hours. A sky calculation puts up to about 3.8 hours of dark core viewing on the best nights at 40 degrees north, and under two hours at 48 degrees north, because nights are short. Northern lights remain possible under clear, dark skies while the Sun is on the declining side of Solar Cycle 25, but check NOAA’s aurora forecast rather than counting on a display.

What can Wyoming families do outside in May 2027, and which park roads are open?

• Yellowstone’s interior roads open in stages

  Spring openings spread across April and May; 2027 dates had not been posted · Yellowstone National Park

  For 2026, the park projected April 17 for the West and North entrances and their main roads, May 1 for the East Entrance over Sylvan Pass and the Canyon to Bridge Bay road, May 8 for the South Entrance, West Thumb and Craig Pass, and May 22 for Dunraven Pass. The park’s April 2026 release shows a late-season storm pushed back that year’s first-day opening to noon, which is a reminder that all dates depend on weather. Spring means limited services and snow-covered trails. Call (307) 344-2117 or look at the live road map.

• The Beartooth Highway

  Typically the Friday of Memorial Day weekend; check · US 212 and the Chief Joseph Scenic Byway, WY 296

  The park service says the Beartooth Highway typically opens the Friday of Memorial Day weekend and may close early if winter weather returns. Monday, May 31 is Memorial Day this year, but the actual opening day will depend on the plow crews and the snow.

• Grand Teton’s roads, and a wildlife closure

  Teton Park Road open from May 1; Moose-Wilson Road mid-May by conditions; Willow Flats closed May 15 to July 15 · Grand Teton National Park

  The park says the Teton Park Road is closed from November 1 to April 30 and that keeps the Moose-Wilson Road shut until about mid-May, with conditions deciding. Willow Flats is closed to public entry from May 15 through July 15, or when posted, and the Grassy Lake Road in the Rockefeller Parkway stays closed through May 31 or later because of snow. Call (307) 739-3399 for current road status.

• Fishing in Yellowstone

  Usually the Saturday of Memorial Day weekend · Yellowstone National Park

  The park’s regulations say the general fishing season runs from the Saturday of Memorial Day weekend through October 31, which in 2027 would be May 29. Some stretches of the Firehole, Gibbon and Madison rivers get a head start on May 1, and the Gardner River and lower Madison are open all year. Check the park’s current regulations because streams can be closed for low water or heat.

• Global Big Day and World Migratory Bird Day

  Annual in May; 2026 was May 9 and the 2027 date had not been posted · Your backyard, a local park or a refuge

  The World Migratory Bird Day site lists its 2026 events on May 9 and October 10 and had no 2027 date when we looked. The Cheyenne chapter of Audubon listed Global Big Day and World Migratory Bird Day together on May 9, 2026. Count what you see for 15 minutes and enter it in eBird.

• Big Day bird counts

  Annual in May; check with the chapter · Cheyenne, Platte and Goshen counties, and the Sheridan area

  Cheyenne Audubon’s 2026 calendar had a Cheyenne Big Day Bird Count starting at Lions Park on May 16 and a Platte and Goshen counties count at Guernsey Fish Ponds on May 9. Bighorn Audubon in Sheridan lists a Spring Count, with the last date posted being May 10, 2025, and a monthly walk at The Brinton Museum on the third Saturday in its 2026 calendar. Neither chapter had posted 2027 plans, so write to them. The Casper chapter, Murie Audubon, meets the second Thursday of September through May.

• Join NestWatch

  Nest season, through June · A shrub, nest box or fence line near you

  Cornell’s NestWatch is open to anyone and asks you to read its Code of Conduct before you look for nests, then record what you see. The point is to watch from a distance and keep your visits short, never to peer into every nest.

• Become a weather watcher

  Any day · Your yard

  CoCoRaHS says it is the largest source of daily precipitation reports in North America, with more than 28,000 observers measuring rain, hail and snow, and that it takes about five minutes a day. A May hailstorm is just the kind of event it likes to map.

• Memorial Day weekend

  Monday, May 31, 2027 · National parks and state parks

  The long weekend is when Yellowstone fishing opens and the Beartooth Highway usually reopens, and parks will be crowded. Go early, carry bear spray, and plan for a road that is still closed.

Safety notes for May in Wyoming