THOUGH I AM HAPPY to exclude deer from my garden, my approach to birds is quite another story. The place is basically theirs: I design and plant for them, provide year-round water for them, and most important use no chemical fertilizers, herbicides or pesticides that interrupt the food chain and their well-being. More than 60 kinds have visited me right here in the back yard over the years; most of those are repeat annual visitors.

The winter of 2008, I was treated to a newcomer, as were many lucky birders in the northern states. One of the so-called winter finches, the pine grosbeak, traveled farther south than normal in what is termed an irruption, or abnormal pattern of wintertime travel. 

Contrary to what might seem like good motivation to people, the birds don’t necessarily travel to escape unusual cold. They follow the food—meaning when supplies are scarce where they normally winter, they move on in search of a good supply. The reason my place looked good enough for a flock to spend not a day but three months with me: crabapples, of which I have perhaps 10 trees representing five varieties. I was glad to be the accidental host to these friendly birds, and watched them share the feast with robins and cedar waxwings (the usual recipients) all winter long.

Learn more about where they, and many other irruptive species in the winter of 2007-08, had traveled from: the boreal forest of Canada.