By Sam Archibald, Lead Field Educator

The first sign of spring is a flash of blue.

Mountain bluebirds

Long before the snowpack begins to shrink, typically in the first week of March, Mountain Bluebirds appear in Yellowstone, launching a new year’s wave of spring migration. I saw my first bluebird around Mammoth on March 10 this year, an exciting moment that foreshadows all the phenological firsts throughout the year: the first grizzly of the year (4/1 for me), the first bison calf (4/8), the first wildflowers (Sagebrush Buttercups 4/9), and countless other moments worth celebrating as Yellowstone comes alive and tilts back toward summer.

Early spring is often a time of yearning. The first warm days after months of freezing ignite a desire for cookouts, camping, and all the adventures we associate with summer, even though snow remains throughout much of the park through May and even longer in the high country. Spring in the Northern Rockies can bring all four seasons in a day; the only guarantee is mud. So, in this interlude between skiing and hiking seasons, I count each new bird species as a promise of things to come.

Sandhill cranes

Our earliest birds show up in March. First the Mountain Bluebirds, then American Robins soon after. This year, they appeared in Gardiner a day later (3/11), and then slowly spread up into the park over the next few days. By March 18, Red-winged Blackbirds and Sandhill Cranes had returned, their unmistakable calls echoing across the still-snowy Blacktail Plateau. Western Meadowlarks, an icon of spring in the west as the state bird of both Montana and Wyoming, joined them in growing chorus the following week.

And the choir grows even more throughout April. Just as each day brings a few more minutes of daylight, so too do more bird species seemingly appear each new day in the park. After a few isolated sightings in February and March, Red-Tailed Hawks began showing up in droves throughout the first week in April, with other raptors (Peregrine Falcons and Osprey on 4/5, Turkey Vultures on 4/6, and Sharp-shinned Hawks on 4/9) in close pursuit. On April 18, there were 9 different duck species at Slough Creek including wigeons, gadwalls, and Yellowstone’s three types of teals. Many species, like the American Kestrels that showed up on March 18, are returning home to the territories where they were born. Others, like the brilliantly colored Wood Duck swimming around Blacktail Pond earlier this week, are just stopping by on their way to more northern breeding territories. And some of the migrations are actually departures. Many of the Golden Eagles that overwinter in Yellowstone, for example, migrate up to Canada and Alaska in the spring, though their departures are harder to record than the waves of new arrivals.

Osprey with brown trout

There are many reasons to pay attention to avian phenology. Birds are an indicator species, meaning that they are especially sensitive to environmental changes and provide an early gauge to assess the ecological ramifications of climate disruptions and natural or anthropogenic disasters. They are not only the first migratory animals to arrive in the park, they also must travel the furthest, in some cases migrating from Central and South America. This means that they must begin their migrations weeks in advance with no knowledge of the conditions in Yellowstone. Paying attention to when birds appear can help us assess how climate change is already affecting ecosystems across the hemisphere, as well as the integrity of migration corridors and the health of these cosmopolitan populations.

But the truth is that I would pay attention regardless. Finding your first bluebird of the year is like meeting an old friend you haven’t seen for a while. It brings joy, encourages observation, and makes familiar landscapes new again. This past week I saw my first Harlequin Ducks, Yellow Warblers, Lesser Yellowlegs, Northern Shovelers, Yellow-headed Blackbirds, Redheads, and Eared Grebes. I have yet to see a Western Tanager, but I’m looking forward to it.

Cover Image: Harlequin Duck, LeHardy Rapids

All images by YF / Matt Ludin