The Perils of Migration
The birds are heading south! The fall migration in on. Animals basically have three ways to respond to the upcoming winter: migrate, hibernate, or stay and endure it. For the majority of our birds, heading for more suitable climates is the best option.
Migrating is an exhausting and uncertain business. The risks can be categorized into four areas: predation, collisions, extreme weather and climate, and habitat loss and degradation. Not all of the birds will make it to their winter destination, but most of them will. And by doing so, they can take advantage of the geographic variations in seasonal abundance of foods such as seeds, fruits, and insects.
Some among us may have the impression that the birds are flying non-stop to their winter destinations, but that is not always the case. Some birds do fly non-stop, but most will make several stops along the way to rest and refuel. Think of them, not as long non-stop flights, but as puddle jumpers. The stops may last for several days for every few days of flight. And even though some birds may lose body weight during migration, they appear to make it to their destination without becoming exhausted in the process.
It might surprise you, but these stops are not random. Some are even quite specific (A good example would be the sandhill cranes congregating on the Platte River in Nebraska in the spring). As a result, land use changes in some of these areas can have a significant impact on the birds ability to make it to their destinations. Scientists are trying to identify these important stopover areas and protect them. It has been estimated that around one half of the priority stopover areas are in human dominated landscapes and less than 10% are protected.
In addition to the potential detrimental effects of habitat loss and degradation in stopover areas, other risk factors to consider include our changing climate and associated extreme weather events. Predation is always a factor. And it is still not well understood, but lit-up skyscrapers, along with many other lit-up landscapes are causing birds to get disoriented which increases bird collisions.
The trip is indeed a risky one. And it is getting riskier. Here is wishing safe travels to our feathered friends.