Front Stoop Birding: Warblers Come to Us

On days like this, when we want to go birding, we just walk out to our front stoop, stand on the steps, and look up:

When we look up from our front stoop, we see the branches and opening leaves of our American Elms.

If we look carefully we’ll see tiny birds high above, flitting through the branches and picking at the opening leaves. When we look through our binoculars, we see things like this:

Cape May Warbler, only partly obscured by elm leaves. (I like this warbler more than most because it's named after a place on the New Jersey seashore where my family went when I was young.)

Warblers are small birds, often brightly colored, that spend the winter far south and then migrate north to breed. The Cape May Warbler is just one of the 35 different kinds that may pass through our neighborhood in the spring. So far this year we’ve seen and heard 14 different kinds of warblers on our block. Here’s the full list (as of 5 p.m. on Friday, May 8th):

Tennessee Warbler

Orange-crowned Warbler

Nashville Warbler

Yellow Warbler

Chestnut-sided Warbler

Cape May Warbler

Yellow-rumped Warbler

Black-throated Green Warbler

Pine Warbler

Palm Warbler

Black-and-White Warbler

Blackpoll Warbler

Northern Waterthrush

Wilson’s Warbler

While looking for warbler, we’ve also found Scarlet Tanagers, Baltimore Orioles, an Orchard Oriole, Blue-gray Gnatcatchers, Warbling Vireos, a Philadelphia Vireo, and Ruby-crowned and Golden-crowned Kinglets. As we described in earlier posts, a few of these species were hanging out in the street or on rooftops a week or so ago. But the birds we’re seeing now are mostly way high up — so high that our necks get sore looking at them (This bird-induced pain is called “warbler neck.”)

Why do all these birds come to our block? It’s the opening tree buds with their soft leaves, which make good food for insects like this caterpillar:

It's not just a tiny caterpillar on the weather-worn sidewalk -- it's warbler food!

There must be thousands of these caterpillars in our trees, eating leaves and in turn being eaten by birds. But these tiny, soft caterpillars are not defenseless. Aaron watched as the caterpillar in this photo descended from tree top to sidewalk on a silken thread. As near as we can tell, a bird was about to eat the caterpillar. Somehow it knew what was coming, and it “leapt” from its leaf. But it was attached to the tree by homemade silk — the same silk it will one day use to make a cocoon — so it descended slowly. Like a rock climber, it repelled from the heights rather than falling to its death.

Here’s what we think may happen next, based on evidence pieced together over several springs and summers. If the caterpillar avoids being eaten by ground-feeding Palm Warblers, it may find cover in the soil or perhaps under a rock. Then it may emerge at night to feed on elm leaves that have fallen to the ground. And, somehow, elm twigs have been falling for the past few days, even when there’s no wind and no rain. Why? We’re not sure, but we can’t help wondering if caterpillars still in the trees have something to do with it.

We’re still looking for field evidence and scientific references to support or refute our pieced-together story. If you can help, please do (using the comments section below).

So, we’ll continue watching birds — and bugs — from our front stoop. Go here to read the latest bird counts for our block.

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Updates:

On Thursday, May 14, this post won an award at the I and the Bird #100 blog carnival (as did eveyone else who participated). To read all about, please go here.

On Saturday morning, May 9th, we did a Spring Bird Count at Columbus Park, about a mile from our home. We found 25 different kinds of warblers in the Park in a bit more about five hours. We don’t have to travel far from our front stoop to see great birds. (That’s why we dedicated this blog to “neighborhood nature.”) Go here to read more about our Spring Bird Count.

On Tuesday, May 5th, the New York Times published an article describing how tree-bud opening, caterpillar hatching, and the migration of caterpillar-eating birds may no longer coincide because of climate change. Go here to read the article.

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Updates on the 2009 warbler list for our yard:

On Thursday morning, May 14, we saw the first American Redstart to visit our yard this year. That was year-yard-warbler number 18.

On Wednesday, May 13, we heard and saw the first Magnolia Warbler to visit our yard this year. That was year-yard-warbler number 17.

On Tuesday, May 12, we heard the first Common Yellowthroat to visit our yard this year. That was year-yard-warbler number 16.

On Friday, May 8th (later that same day), we saw the first Bay-breasted Warbler to visit our yard this year. That was year-yard-warbler number 15.