May in Yellowstone

Seasonal Phenology Notes from the Greater Yellowstone Area

On this page you’ll find May phenology notes for Yellowstone and surrounding areas (mainly Cody, WY). If you’re wondering what it’s like in Yellowstone in May – browse through to get an idea.

Blog Post: What May like in Yellowstone?

May 1

  • 2015: Cody | North Fork – A Grizzly Bear sow and cub were seen just above Newton Spring at Newton Spring Picnic Area.

May 2

  • 2014: Yellowstone | Upper Geyser Basin – Marsh Marigolds and Spring Beauties blooming on the section of the path leading from the bridge over the Firehole River to Geyser Hill. Also spied some Yellow Fritillaria blooming in the Grand Geyser area and Yellow Monkey Flowers and Fringed Gentian blooming in the Chinese Spring area.

May 4

  • 2014: Cody | In Town – the first apple blossoms are blooming at my mom’s house as are other flowering trees and shrubs in town – just starting to open (and a call for snow in the forecast, of course).
  • 2015: Yellowstone | Fishing Bridge – Ice Out today.
  • 2015: Yellowstone | Sylvan Pass – 3 Bison that wintered on the North Fork of the Shoshone were seen moving over Sylvan Pass.
  • 2019: Yellowstone | Yellowstone Lake – Other than small areas of open water near thermal areas, the lake is completely frozen and snow covered. Ice out is a long ways away.

May 5

  • 2015: Cody | Wapiti – Good steady rain moved in this evening and through at least part of the night. Total of 0.27″ on the rain guage. Blooming: Locoweed, Death Camus, Yellow Violas, Larkspur, Arrowleaf Balsamroot.

May 10

  • 2014: Cody | In Town – Huge snowflakes coming down this morning that accounted for about an inch of snow that quickly melted. (Last snowfall)
  • 2015: Cody | Wapiti – A pair of Chukars circled our house and the neighbor’s house through the day – looking for a nest site?
  • 2015: Cody | Beck Lake and Alkali Lake – Quite an early evening friends had May 10th at Beck and Alkali Lakes south of the Greybull highway (US 14-16-20)!  Many of each species although only 2 Sandhill Cranes and one hawk:

Northern Shoveler, Mallard, Bufflehead, Canvasback, Western Grebe, Eared Grebe, Marbled Godwit, Wilson’s Phalarope, Sandhill Crane, Coot, Avocet, Tree Swallow, Cliff Swallow, Ravens, Red winged Blackbird, Meadowlark, Red Tailed Hawk

May 11

  • 2015: Yellowstone | Mary Bay – A pair of Ravens were spotted, each with a tuft of bison fur in their beaks. Assuming they are nest building.

May 13

  • 1937: Yellowstone – For the second time this season a nest of Clark’s Nutcracker (Nucifraga columbiana) was seen and photographed. In company with Dr. Bauer and District Ranger David Condon, I discovered the nest while taking movies of a Hairy Woodpecker (Dryobates villosus). After we had observed the nest and had taken pictures from the ground, I climbed a nearby tree for more movies.These birds were very bountiful in their offering, for while we watched and photographed them, the female cleaned out her nest and then the male came in. The female soon departed and the male proceeded to feed three and perhaps four yawning mouths which were thrust up from the depths of the nest. This task complete, he settled down on the nest for his turn with the little family. -W.E. Kearns (from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)

May 14

  • 2015: Cody | Wapiti – Indian Paintbrush blooming as are Evening Primroses, and Larkspur. Nearly all of the Arrowleaf Balsamroot have been nipped off by, I’m guessing, the deer, though we’ve not seen them for the past two or three days. The rains we have received – mostly showers moving through each day – also let the first mushrooms to be found.

May 15

  • 1937: Yellowstone | Tower Falls – The first elk calf (Cervus canadensis) of the season was seen today by Dr. Murie and Mr. Russell Grater about a mile northeast of Tower Falls Ranger Station. -W.E. Kearns (from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)
  • 2014: Sunlight Basin | Swamp Lake – Trip Report for the visit to Swamp Lake

May 16

  • 1938: Yellowstone | Madison River Valley – At 2:10 p.m. on May 16, 1938, Mr. Jack E. Haynes, Mr. E. B. Ballard and myself noted a solitary elk cow on a small island in the Madison River, a mile or two below Madison Junction. On the downstream tip of the island a pair of Canada geese (Branta canadensis canadensis) were apparently building a nest. As we watched, the elk moved down the island toward the geese. As the elk approached within a few feet the geese rose into the air and diving at it launched a first-class attack on the elk. As far as we could see, the geese were striking at the elk with both beaks and bodies. The elk, displaying much discomfiture, dashed into the river, plunged perhaps 50 feet down the stream and then, turning, dashed toward the right bank. The geese continued their attack until the elk, on the dead run and shaking her head, reached the fringe of the timber. The geese then returned to the point at which they were first observed. – Edmund B. Rogers (from Yellowstone Nature Notes Vol XV, Nos. 5-6 | Leaves from our Diaries)
  • 2014: Cody | North Fork – Trip Report for the Owl Prowl with Spring into Yellowstone.

May 17

  • 1937: Yellowstone | Likely the Cooke City Ranger Station area – We were awakened this morning by a Ruffed Grouse (Bonasa umbellus) drumming near our window at 4:30 a.m. He apparently did not see us and we watched his antics with a great deal of interest. The two pair of Hairy Woodpeckers which have been seen during the winter are still with us as, they were all seen again today. – Marguerite L. Arnold(from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)
  • 1937: Yellowstone | Swan Lake – Swan Lake has become the breeding ground for many wildfowl since Dr. Harlow B. Mills had the small dam placed to hold back sufficient water to protect the nesting Trumpeter Swan (Cygnus buccinator.) The area, now more than double the size of the original lake and rich in natural food found in the grasses and reeds, is also a favorite resting place for migratory waterfowl.It is no wonder then that the rarely observed Wilson Phalaropes (Steganopus tricolor) should choose such a fine habitat for a visit and perhaps for a home site. This evening five females and three males of this interesting species were seen and were observed for over an hour. With this species, the females are the aggressors and are more brightly colored. After the eggs are laid, the males take care of the incubation of the eggs while the females enjoy their freedom in little groups, disporting themselves in a most carefree manner. – W.E. Kearns (from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)

May 18

  • 1937: Yellowstone | Mammoth – A Badger (Taxidea taxus) which has been living between the Museum and the Chapel was busily engaged digging up Grounds Squirrels (Citellus armatus) during the past week. He was eating the small ones and killing the large ones and then burying them. This morning a fine close-up photograph in Kodachrome was taken of him. – C. Max Bauer (from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)
  • 2014: Cody | North Fork, In Town, Belfry Highway – Trip Report for Raptors of the North Fork with Spring into Yellowstone.

May 19

  • 1937: Yellowstone – Three Wilson Phalaropes two female and one male, were seen this afternoon at Beach Spring. This is but the second time in three years that I have had the pleasure of observing these casual visitors, or secretive summer residents, whichever they may be. – W.E. Kearns (from Yellowstone Nature Notes Vol XIV, No 5 | Leaves from our Diaries)
  • 2014: Cody | East on the Graybull Highway – The Sandhill Cranes took their colts out for a stroll. Fox kits were still near the den. Great Horned Owls still in the nest as was the Red-tailed Hawk. Watched a Northern Harrier float over the grass.

May 20

  • 1938: Yellowstone | Mud Volcano Area – On May 20, 1938, about 3:35 p.m., Mr. Jack E. Haynes, Mr. Joe Joffe and myself observed an immature moose grazing in an open meadow a hundred yards to the west of the highway, a short distance south of the Mud Volcano. When first seen, the animal was moving along slowly in a standing position. In a few moments it got down on its front “knees” and continued to graze, moving a considerable distance in this position. (Mr. Haynes took a moving picture of it.) – Edmund B. Rogers (from Yellowstone Nature Notes Vol XV, Nos. 5-6 | Leaves from our Diaries)
  • 2014: Yellowstone | West Thumb Geyser Basin – Barrow’s Goldeneye exhibiting some breeding behavior.
  • 2014: Cody | Pahaska – Grizzly Bears seen on the hillside above. A sow with two older cubs. (JW)
  • 2019: Yellowstone – Yellowstone Tour Guides saw their first elk calf today!

May 24

  • 2014: Cody | In Town – Cody received about 1/2″ of rain in the afternoon. Petals from the apple blossoms dropping all over town, and the lilacs are starting to bloom. Driving by the Great Horned Owl nest by the old Sage Creek Schoolhouse, we noticed it was empty. (JW)
  • 2014: Cody | McCullough Peaks – Every small pond was rich with the sound of Boreal Chorus Frogs. Blooming along the McCullough Peaks Road: Arrowleaf Balsamroot, Purple Phlox (starting to fade), Shooting stars, Bluebells, a type of yellow yarrow (??). (JW)

May 25

  • 2014: Beartooth Highway | Between Beartooth Lake and the Sunlight Basin Road junction – First report of an Elk calf seen. It was born minutes before being observed. (RH & MJ)
  • 2014: Sunlight Basin | Swamp Lake – Sandhill Crane still incubating on a nest there (first seen on 16 May incubating). Found in bloom: Pasque Flowers, Bluebells, Bistort, Oregon Grape, King’s Crown Sedum (I think King’s Crown – close to blooming. We didn’t walk into the Fen, but stayed along the road side. American Coots breeding. 57° F at the top of Dead Indian Hill at 3:30 PM – partly cloudy.

May 27

  • 1938: Yellowstone – While talking over the telephone this afternoon about 5:00 p.m., I noticed that we had visitors in our yard. Two huge grizzlies (Ursus horribilus imperator) were investigating the Weather Checking Station at a distance of about 40 feet from the Ranger Station. Apparently satisfied with their examination, the huge beasts moved down toward the road. When they reached the footpath leading from the ranger station to the checking station, they stopped suddenly and cautiously sniffed the trail over which I had passed but a few minutes before. My fresh tracks seemed objectionable to them, and they turned back up hill, woofing and slapping at each other in a carefree mood. After a short period of scuffling, they disappeared in the timber above the station. – E. L. Arnold (from Yellowstone Nature Notes Vol XV, Nos. 5-6 | Leaves from our Diaries)

May 28

  • 2014: Cody | Near Town – A report came in that three baby Pronghorn were spotted today.

May 30

  • 1966: GTNP | Togwotee Pass – J & W. O. fished Birthday Lake [Brooks Lake]. Worms – thru ice (melted spot) – [caught] limit. Jim and Ben up to Clear Lake – frozen over. D & L walked circle – flower hunting – Shooting StarsOrchids. (Lyndall’s Journal)

May 31

  • 1966: GTNP | Togwotee Pass  – Fishermen to Birthday Lake [Brooks Lake] again. Not limit. Fish fry at noon. (Lyndall’s Journal)
  • 2014: Cody | In Town – A heavy thunderstorm moved through quickly this afternoon leaving 3/4″ in that time. (JW)