Logic would tell us that birds are free to fly anywhere to find better food or cuter mates. It turns out that they operate within the same boundaries as many ground based animals. A Bird's Eye View on Freshare.net discusses research on flight patterns of Missouri's resident birds such as jays, woodpeckers and cardinals.
Dylan Kesler, assistant professor in fisheries and wildlife at the University of Missouri’s School of Natural Resources has radio-tagged red bellied woodpeckers, then tracked and plotted their movements with GPS. To quote:
Those studies provided preliminary confirmation of what has been suspected by conservationists since the 1990s – that birds make landscape-influenced flight decisions along paths where they can immediately dive into tree cover to escape predators and readily find food.
The research also revealed that the birds avoid large areas without trees. Such exposure can make them easy pickings for predators. These open habitat features include roads, rivers and forest gaps, as well as other man-made landscape features where there is no easy cover.
|Highway W- Click to enlarge|
This has important implications in our time of habitat fragmentation. We are steadily reducing their territory and fragmenting their populations. How small is too small? O nly time will tell.
I would encourage you to read A Birds Eye View and look at their maps.