Species which breed west of the Rocky Mountains spend the winter in northern and western Mexico. Some eastern species travel to the islands of the West Indies and the Caribbean. A few migratory birds fly straight to South America without stopping. The rest, or approximately one-third of the total, migrate to the Yucatan Peninsula, the southern Mexican state of Chiapus and the Peten region of Guatemala. A quick look at a map of the Western Hemisphere should reveal a clue to this question.
Migration is hard work.
It s no wonder that birds which fly over the Gulf of Mexico seek out the closest possible destination to land. While it is not an airport, the north coast of the Yucatan Peninsula does serve as one large arrival terminal for huge numbers of birds moving over the Gulf each autumn. Energy to Burn Birds migrating over land from eastern and central regions of Canada and the U.S. to southern Mexico will eventually hit a big hurdle, the Gulf of Mexico. The Gulf covers over 1,000 square km. and has only a few scattered, tiny islands. Upon reaching the Gulf, birds must decide whether to fly around the Gulf, stopping at wood lots along the way, or fly straight over it.