As fall advances toward winter here in the northern hemisphere, we say a fond farewell to most of the birds we have enjoyed watching in our backyards, local parks, tree-lined streets and no-mow patches scattered across the landscape. We’ll have to wait, in some cases, eight or nine months for them to return. At the same time, many people might welcome a decline in the number of insects sharing their outdoor spaces. The timing of those changes is not a coincidence though. Insects are an essential energy source for migratory birds throughout the year, and the timing of migratory movements of many species have evolved to track seasonal changes in insect abundance across their ranges. Insects and other invertebrates are a main source of protein for many migratory landbirds. During the breeding season, female birds require protein to produce eggs, and parents feed insects to their young to provide protein for growth. During migration, birds need protein that insects provide to...