The night sky in spring may seem serene, where nothing is going on. But in fact, it is bustling with energy and activity.
Why do birds migrate? First, to take advantage of a plentiful food source at their destination. Most birds in forest habitats feed on caterpillars and other invertebrates, fruits, and nectar. All are abundant during the warmer months. Also, there is less competition for nesting territories than in the tropics. During the day, most migrants land to rest and feed. Warblers—small, colorful “butterflies of the bird world”—flit from branch to branch to feed on the caterpillar and other insect “hatches” that they depend on as they migrate north.
Most people don’t look up to notice them in the trees or realize they are even there. Nor do they hear their songs, a combination of trills and buzzes. As long as there are the right native trees, shrubs, and other plants with insects feeding on leaves, you will find warblers and other migrants passing through even in cities.
It’s not easy being a migrant. Many species of neotropical migrants are experiencing long-term population decline due to habitat loss at both their breeding and wintering grounds, not to mention their re-fueling stops. And there are other threats. Birds collide with skyscrapers, attracted by bright lights at night or fooled by reflections in the glass during the day. Millions are killed every year by predators, such as free-roaming cats. Climate change may make the availability of food out of sync with the birds’ arrival.
What can you do? Actually, you can help birds greatly by providing critical stopover habitat in your own yard or neighborhood. Plant native trees such as willows, oaks, cherries, and birches. For planting information in your area, go to the National Audubon Society’s Plants for Birds or the National Wildlife Federation’s Native Plant Finder. Consider converting your lawn for birds. Our lawns are actually biological deserts and we are a turf nation. The amount of turf in the United States equals the size of New England. Imagine if each year we committed to taking out just some of the grass in our yards, lots, and parks and planted native trees, shrubs, and wildflowers. We would increase our local biodiversity and those warblers might just stop by.