|A Common Grackle loaded with caterpillars for its young.|
Many birds are now nesting in our area. Many others are continuing their journey North but make important pit stops here to gather strength and gas-up on food for their long journey. The first couple of weeks of May are often considered the peak of migration for the DC metropolitan region. The reason for this has to do with the emergence of insect food to sustain them. Indeed, some 96% of terrestrial birds feed on insects and other invertebrates. It could be said that we owe the phenomenon of migration to the insects emerging this time of year.
Even some birds that we normally think of as feeding on other things provide insects to their young for the protein they need to grow, including hummingbirds. Other birds, such as warblers, are almost exclusively insect gleaners. No insect group provides more of this food than the caterpillars of moths and butterflies. Their abundance this time of year is the primary reason for our richness in bird life during this season. The vast majority of caterpillars born end up as food for birds and other animals. In fact, all our bats eat insects, and the moths that most caterpillars turn into are their favorites.
So the next time you see a caterpillar or bump into one dangling from a silken thread, remember all the animals that depend on it. Of course the caterpillars do not want to be eaten and have a myriad of ways to protect themselves, but that is food for another Blog...