Migratory restlessness is a term used by scientists to describe the urge birds feel in the autumn and spring, calling them to migrate. It also refers to the fact that even when caged, birds of migratory species will display a restlessness during these periods. While life has seemed very local here lately for my family, between back-to-school preparations and enjoying the bounty of local produce, long-distance migrants are already passing through the area en route from Canada to their wintering grounds.
Scientists still agree that there are factors we haven’t yet guessed in the reasons birds migrate, but in general it is believed that birds that migrate long distances do so to access abundant food sources, helping to ensure greatest overall species fitness. Competition for nesting habitat is another important factor. As such, long-distance migratory birds leave behind their wintering grounds in the tropics, where there is a high concentration of local and migratory birds, to access the abundance of space and food that becomes available after winter in the north. Long-distance migratory birds return south in the autumn because lack of bountiful food during our colder months in the north can not support high concentrations of resident winter bird populations. In addition, there are other factors involved in the reasons birds migrate.
How birds know when it is time to go is also still a mystery scientists are trying to determine. If it is the issue of following food alone, why would the earliest migrants leave in July and August – I know the bugs are still buzzing at my house. Some bird species are quite particular in their diet and that preferred food may be in decline or moving on though to the casual observer it may seem there are insects aplenty. Don’t forget that plants are food sources that follow seasonal fluctuations as well. Migratory birds are also hard-wired with an internal clock that triggers the urge to move on, the migratory restlessness. Day length, daily temperature fluctuations, and local geographic changes may contribute to triggering the urge, but the reasons are still being debated.
Long-distance fliers need rest stops to refuel. One exceptional place to view migratory birds in the Finger Lakes is Montezuma National Wildlife Refuge. Other places to try would be wetlands, open fields for some grassland species, wildlife management areas with a range of habitats, and your backyard birdfeeder. I know I always have to be careful when observing migratory birds in the autumn because, though life seems so local in one way, I have a restless spirit that calls me to pack my bags and fly away too!
by Gabrielle L. Wheeler
