The Trill of a Pine Warbler

On a cool morning in mid-April, two friends and I ambled down a gravel road toward their family cabin. What we’d planned as a quick drive to scout for black ash trees to harvest for basketmaking had turned into a longer trek because of a maple tree whose rotten base had unexpectedly given way and blocked the road. A walk through the spring woods was no hardship, though, and we identified six trees to harvest during the first week in June!

Black ashes like to grow in vernal pools that are wet in the springtime. Photo by Emily Stone.

(If you’d be willing to help April Ogimaakwe Stone, member of the Bad River Band of Lake Superior Chippewa, harvest and pound the trees into basket strips during the first week of June, check the Cable Natural History Museum website for details!)

Past the cheerful red cabin and through the deep green of a pine grove the cold water of Lake Namakagon glimmered. I imagined that the lake was shimmying with the relief of being released from the grip of rigid ice. The local loons were back, but not many other birds had returned to the Northwoods yet. We’d spooked a couple of hermit thrushes earlier, but they just bobbed their rusty tails and vanished into the woods without giving us the pleasure of their flute-like song.

Then a musical trill sounded from the treetops. Pine warbler! These hardy birds spend the winter in the southeast third of the United States instead of flying all the way to Central or South America like many warblers. Some pine warblers live year-round in the Southeast, welcoming their northern counterparts into large winter flocks, then nesting once the competition clears out. And they sing all year, even in winter and even on migration. Back in early March when I participated in Loon Camp in South Carolina, our morning bird walks were filled with the trills of pine warblers. I felt like I was hearing the voice of an old friend.

With such a short migration, pine warblers can start moving north as soon as the weather permits. Their bright yellow feathers arrive right along with early spring sunshine.

The gravity of the lake and the sloping bank pulled us down until we were standing on the shore. My companion gasped in the middle of a sentence as a pine warbler darted over my head and landed on rough spruce bark a few feet way. Pine warbler males are known to be territorial for most of the year. They will fly at many different intruders, not just other pine warblers. Was he warning us to stay away?

He swooped to a rock wall and paused mid-hop to belt out a trill. It was easy to identify the source of this song as we watched his stout beak open and his white wing bars vibrate with the effort, but chipping sparrows and dark-eyed juncos are two other early returning birds who sound very similar. To my ear, the variation of the speed and tone of the trill within each species is just as large as the variation between the three species. Juncos and sparrows tend to sing from lower branches, bushes, and even while on the ground, but so did this pine warbler!

In general, if I hear a trill coming from high in a pine tree, or especially from a whole cluster of pine trees, my first guess is pine warbler. They are aptly named, as they are rarely spotted anywhere but in pine trees. Like nuthatches, they forage by hopping slowly along trunks and branches to find insects.

A few days later a flash of yellow interrupted the usual succession of chickadees and nuthatches visiting the bird feeder at my kitchen window. Insects are pine warblers’ main food source during the breeding season, but because they are adapted to eating pine nuts in the winter, they are far more likely than other warblers to visit your bird feeder. Just like ruffed grouse, their gizzards grow larger when they need to digest a higher proportion of tough seeds.

The round, yellow, bundle of energy on my feeder flew briefly out of sight, but immediately returned—or was that another pine warbler taking turns? The bird cocked their head as if they had some questions for me, too!

Unlike many birds, pine warbler numbers have been increasing in recent years as some pine trees recover from logging and expand into previously deciduous forests. For at least a century there have been plenty of evergreen trees near this house, but this is the first time I’ve seen pine warblers at my bird feeders, and I’ve never observed them nesting here. Perhaps with their increasing population they’ll have to expand into my yard. What a trill that would be!

Emily’s third book, Natural Connections3: A Web Endlessly Woven, is available to purchase at www.cablemuseum.org/books and at your local independent bookstore, too.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Summer Calendar is open for registration! The Museum is closed until May 12 to allow for construction of our new exhibit, The Wetland Way. Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.