Summer World_ A Season of Bounty - Bernd Heinrich [20]
Temporary pools are a prime component of the wood frogs’ summer world, and I conclude that almost everything they do is highly evolved to take advantage of it. Their specific behavioral mechanisms blur the meaning of, or give new meaning to, our ideas of “cooperation” and “competition.”
4
The Early Birds
11 March 2006. IT’S ALMOST TIME FOR THE FIRST BIRDS to start coming back, and I’ve gone into a frenzy with handsaw, hammer, and nails, making nine birdhouses. I hung them around our house, thinking of wrens, tree swallows, and maybe bluebirds. My timing is right. By eight AM the first red-winged blackbirds arrive below in the beaver bog. I see four of them “on station” calling “oog-la-ee” from the tops of bushes and cattails. After an hour they fly up the hill to our house and land on our bird feeder. Last summer they fed here on sunflower seeds, which are not even visible from the outside and can be reached only through a little crack. These birds today act as though they are familiar with the feeder situation, and I suspect that some of them are the same bunch every summer. In the next several weeks they will come to the feeder every day, and they often come in small groups; they are still flock birds even though when they fly back down in the bog they spread themselves out. Down there they remain within visual and vocal contact of each other. Grackles also came back today—I saw three circle the bog. Later a relatively tame one came up to our house and perched on a big black cherry tree that shades the front of it. In hopes that it might be Crackle, whom we had rescued last summer from a nest that was crawling with mites and who became our friend and the favorite pet of the kids, I called “Crackle! Crackle!” He didn’t fly off. Instead, he wiped his bill on a twig as though he was distracted or undecided about what to do next.
EARLY BIRDS, THOSE THAT COME BACK WHEN SUMMER IS still only a promise, make me feel hopeful and rejuvenated. Like the wood frogs, they are a sign that life is off again to another great start. Through them I become aware of the risks and gambles that go with life, and appreciate the gift of living.
The first bird may get the worm, and a male bird also has a better chance for getting a good territory. But if being back early were easy, then all birds would do it. Necessarily, if some are early, then others are late, in the same way that there is no winning without losing. The benefits of being early have to be balanced by the costs, or all birds would be early. And there are great costs—the possibility of foul weather and lack of food, both of which kill.
As I’m starting to write this, again in mid-March but a year later (2007), it is time once more for the first migrants to return, but temperatures are dropping and the meteorologists predict twelve to eighteen inches of new snow over the next few days.
The forecast was correct. Then another snowstorm came shortly on the heels of that one. This year, many early birds would have starved. Flocks of dozens to hundreds of returning juncos were by the roadsides along the snowbanks in the Maine woods near my camp. I sank up to my thighs in the snow in the woods next to them where they would normally have been replenishing their spent fuel reserves. Later, in the summer, I saw none of these birds near where they are commonly summer residents.
The average timing of the different species necessarily differs. Bud-feeders and eaters of seeds and berries that stay on the trees can stay north all winter; but those, like the juncos, that feed on the bare ground must leave in the fall after the first snowfall and can return only after the snow melts. Those that feed on flying insects come next, and the caterpillar-hunters can’t risk coming back until after the trees have put on their leaves in late May or early June.
The Red-Winged Blackbirds. Flocks of red-winged blackbirds normally make their first probes into their northern breeding grounds