The warblers fed in silence. I am used to the constant calling of goldfinches and house finches, to the drone of hummingbird wings. The warblers surprised me. They hopped from branch to branch of the desert olives, weaving among them like dappled sunlight. In the stillness of a golden September afternoon they barely made the leaves move. They even squabbled in silence. And they fed.

They fed.

Their silence sang of purpose—of hunger, of need. They ignored me, sitting a few feet away from them on the patio, and darted from tree to tree as the afternoon opened out. I had time to observe their thin, sharp bills working over the leaves, the male’s black cap, the female’s gray-green back. They ignored me when I got up to fetch the bird book from the kitchen. They ignored me when I returned and sat back down, riffling through the pages. Dark feathers under the tails with no white trim; unspotted yellow breasts: Wilson’s warblers, migrants on their way south. They might have flown in from the Yukon; they might be headed to Honduras. New Mexico is halfway in between. No wonder they’re hungry.

The plague of caterpillars in my trees is a windfall to them, a chance to eat their fill and rest before taking up their journey again. Small beaks dart between the webbing that has glued the olives’ apple-green leaves together. They emerge with apple-green caterpillars. Again and again this happens. The warblers gorge themselves all afternoon. They’re back the next day and the following morning, feeding in the same silence, with the same determination. Then they’re gone.

* * * * *

When I call myself a laissez-faire gardener, what I mean is that I often don’t know what I’m doing. So—I often do nothing. I’ve never identified the moths that make such greedy use of my trees. The garden hosts several different species, all of them brown. Only when the leaves of the desert olives stop flowing in the breeze do I realize that the nuisance moths have arrived. They sandwich pairs of leaves tightly around an egg and seal them together. If you peel the leaves apart, a tiny caterpillar squirms in the sudden light, protesting the loss of shelter and food. Even if I were inclined to spray, a spray wouldn’t reach the larvae in their safe dens. I don’t know what else to do, so I leave them be.

The trees are tough little things, native to New Mexico’s high desert. Caterpillars are nothing to them compared to sun and wind, drought and heat. In times of environmental stress they shed leaves anyway and always come back strongly the next year. Their health is not at stake. But I must remind myself of that over and over. Half-eaten leaves dangle untidily from shreds of webbing. Blue sky blooms between the branches in ever-widening swaths. To see damage and not make a mental leap to doom—that takes effort.

So the warblers and their appetites delight me. Then, as time goes on and the feast continues, they fill me with awe. How many days have they gone without such a meal? How many days can they go? I don’t know the answers. I only know that they set out to cross the hemisphere without answers to a great many questions—where they would find food, water, shelter; whether they would survive the long journey south. Somehow they had faith that they would, that they could seek, and the world would provide for them.

Faith? Or instinct? Perhaps they are the same thing for birds. Perhaps faith was once a bird-like instinct of our own. Now it is something we must train ourselves to. Sometimes, suddenly, it leaps to life inside us, and we cast our fate to the winds, answering a visceral call home, trusting that we will find the nurture we need in odd places along the way.

* * * * *

The funny thing is, I planted the desert olives to feed the birds. A mature tree is covered all winter in tiny black fruit. But no birds have ever eaten the olives in my garden. Instead the leaves have fed caterpillars, and the caterpillars have fed migrants and strays. I meant to be generous, just not in this way. My generosity has been an accident born of uncertainty and bad gardening. What are the odds that a pair of tiny birds on a journey of thousands of miles would find my speck of an urban garden and its three small trees covered in pests? The confluence of accident and providence, of plague and feast, takes my breath away.

The day after the warblers leave, a flock of blue-gray gnatcatchers arrives. The gnatcatchers are round like little balls, and gray like days of soft rain. They do not feed in silence. The garden resounds with their dry chatter about safety and presence and food. From the patio chair I can almost reach out and touch one where it perches on a low branch. It regards me for a moment with a bright, interested eye. Then it turns away and hops to another branch, calling out to its kinfolk. One after another, apple-green caterpillars disappear into thin, sharp beaks. One after another, the hungry birds are fed.