How Do Birds Do That?

My hummingbirds vanished weeks ago. I miss them. The chipping sparrows that sang from tall pines near the pool parking lot all summer are gone. Most warblers left in September. As day length and temperatures change, leaves change color, and fall migration gets underway.

Chipping Sparrow

Chipping Sparrow

We think of the birds that nest here as “our birds,” but whose birds are they? Most migrants are here for less than half the year. Baltimore orioles spend more time in Costa Rica than they do in Maryland. The best looks I ever had at yellow-throated warblers were in Jamaica in January.

Many bird species migrate thousands of miles twice a year. Why do they do that? Because they can. It’s mostly about food, of course. They move north to find expanded breeding territories and plenty of insects to feed to babies. They return to southern climes for insects that prosper in those warmer winters. But how do birds know? How do they find their way?

Testing has shown that birds have many navigational tools. A biological GPS, a map sense, helps them navigate. Their inner compass helps them distinguish north from south. They can use the positions of stars and sun, the earth’s magnetic field, local scents, low-frequency sound detection, and even ocean wave patterns.

Flight plans vary. Some species, like robins, travel in flocks, stopping to rest and feed for a few days before moving on. In fact, robins may not even move very far south, if they find enough fruits and berries. Some species, like many shorebirds, do long non-stop flights. Weather affects the flights: cold fronts may hold up migration; winds may blow birds off-course.



But once they get as far south as they want to go, how do they know whether their favorite place is east or west of where they are? Perhaps it’s their own memory of places and routes. Not all questions are answered; scientists are still learning how birds do what they do so well.

With cold weather on its way, I’m feeling grateful for the birds that winter here with us. We have wonderful backyard birds who reside here year-round: cardinals, titmice, doves, and woodpeckers, to name a few stalwarts. House wrens migrate but Carolina wrens stay. Woodpeckers stay because they can pry insects from under winter bark; cardinals and other seed-eaters stay to hunt for crunchy seeds and freeload at our feeders. They are joined by a few species like white-throated sparrows and dark-eyed juncos that nest in the north but have moved south to share our milder winter. They’re familiar annual visitors who help us through the dark times.

Carolina Wren

A stalwart Carolina Wren

Now that twigs are rattling in our mostly leafless trees, I remind myself: our summer birds may have left town, but we still have avian bright spirits to bolster our courage against impending winter. The birds and the seasons are moving as they should.

Mourning Doves and friend

One of our six backyard feeders


What Makes It Really Spring?

Scientifically speaking, the first day of spring is the vernal equinox, when day and night are of equal length. However, a naturalist may have a more personal definition.

OLYMPUS DIGITAL CAMERA For some, spring officially starts when the streaky red hoods of skunk cabbage poke out of a bog. For others, it’s when catkins of bloom dangle from birches, or when chimes of spring peepers ring out, or when bluebells adorn moist woodlands. I’ve sometimes declared it to be spring when I found my first Jack-in-the-pulpits, or a jaunty display of Dutchmen’s breeches, or the pristine white petals of bloodroot.

For many birders, though, Official Spring is marked by the return of an eagerly awaited avian migrant. When a special bird reappears, we feel that the great cycle of life is continuing as it should. And if the birds fulfill their promise to come back, surely we have an added chance at life, too.

Some people claim that the essential requirement for spring is hearing the high-pitched twitters of a woodcock’s wings in courtship flight. That doesn’t work for me; woodcocks are too hard to find these days. I want my spring guaranteed.

My friend Diane declares that it’s not spring until she hears or sees a Louisiana waterthrush. One April day when I was at Paint Branch, I heard the sharp call notes of that very bird. The waterthrush song always makes me smile, with its three slurred “now hear this” introductory notes followed by a mix of conversational phrases. The bird was investigating a boggy area near the creek. He lifted to a tree near me, threw back his stripy head, and sang and sang. Okay, I conceded, who could doubt that it was spring?

Naturally, we all celebrate the return of Eastern phoebes with their bobbing tails and quirky voices; yellow-breasted chats whose eccentric vocalizations issue invisibly from thickets; and Baltimore orioles, fiery bright, tossing melodies from the treetops. Their renewed presence, their music and beauty mean so much after a cold dark winter.

One April when I was at Great Falls, my heart knew it was spring when I saw that the eagle’s nest on Conn Island seemed safe from failure. A majestic parent eagle stood on the huge nest feeding a small dark downy fledgling. The youngster gobbled the parent’s offerings, then struggled over to the high rim of the nest, rested its head as if on a pillow, and went to sleep. The parent, with white head up and yellow eyes watchful, stood guard, while the little one napped in the warm spring sun.

In some years, I’m likely to say spring has arrived with the first sibilant song of a blue-gray gnatcatcher. I love to watch these little bright-eyed charmers as they flit about, flashing their long white-edged tails. They further endear themselves to me by using the orange bud-scales of beeches, my favorite trees, when they build their small round nests.

On an April day when I head for Rock Creek, a day when it’s warm and not windy, bright with sun and a descant of bird song, it’s hard to say which first-of-season bird embodies the true beginning of spring. I can’t choose among delightful options: a northern parula with those over-the-top buzzy notes coming from his brilliant yellow throat, a white-eyed vireo caroling a series of “Chick bury-o chick” songs atop a multiflora rose tangle, and a silent palm warbler with that constantly pumping tail.

As you can see, the bird that “makes it spring” for me is a variable consequence of mood and serendipity. There’s no rule. Rightness is all.

imagesSometimes spring clicks into place for me in an unexpected but thoroughly satisfying way. One early April day while I was in our woods engaged in the ongoing battle with garlic mustard and honeysuckle, I heard a familiar, lively song. I laughed with pleasure. It was our first spring catbird! I hadn’t realized how much I’d missed him. Dapper in his gray suit and black cap, he sang cheerful encouragement while I pulled up invasive plants.

Then a downy woodpecker complained about our empty suet feeder, so I lugged my bagful of weeds to the garage and brought out some suet. The little downy hung back. The first bird to enjoy the feast was my blithe companion, the catbird.

“Welcome home,” I told him. “Now, it’s Officially Spring.”