Some birds, such as robins or grackles, winter in large flocks in the Gulf States. Some of these little birds fly nonstop across the Gulf of Mexico (up to 600 miles). The Ruby-throated Hummingbird nests from the southern United States up into Canada and winters as far south as Panama. Clark's Nutcracker, for example, of the Rocky Mountains nests in the summer high in the mountains then winters in the lower forests. In mountainous areas, birds, mammals and others move just a few miles from upper zones where they breed to the foothills or plains during seasons when the weather is severe and unfavorable. The distance may be a few miles or thousands of miles. Migration usually involves latitudinal or altitudinal travel. Some small songbirds migrate 500-600 miles across the Gulf of Mexico. Some routes cross oceans or huge bodies of water.
The majority of migrants travels along broad airways within these flyways changing their flight direction in response to the direction and force of the wind. Geographic factors, ecological conditions and meteorological conditions determine such routes. These routes run north to south and include the Atlantic oceanic route, the Atlantic Flyway, the Mississippi Flyway, the Central Flyway, the Pacific Flyway, and the Pacific oceanic route (see Section 2). The shape of the continent determines the main routes of migration. Do birds follow established migratory routes? The migratory flights of many migrating birds follow specific routes, sometimes quite well-defined, over long distances. The principal wintering area for Neotropical Migrants extends through Mexico and Central America to Panama it has the highest density of winter bird residents in the world. More than 300 species of birds that nest in the United States and Canada migrate to the West Indies or Central and South America. Where do migrating birds go? Many nesting birds in Canada and the northern United States fly south to the tier of states along the Gulf of Mexico where the winter climate is more favorable and food is abundant.
Summertime at northern latitudes also means more daylight hours to seek food for themselves and their nestlings. In the spring, these birds fly north to habitats where spring and summer provide more food production and less competition for food and nesting sites than in their winter habitat. In winter they migrate to the warmer, southern regions of the United States, Caribbean, Mexico, Central America and South America where food is abundant. North American birds must endure the hazards of winter or migrate to more friendly climates. Adequate food is not available throughout the year in most regions. Most birds require a rich, abundant supply of food at frequent intervals because of their high metabolic rate. These enhance the chances of survival of a bird and its brood. (1) Birds migrate to areas where food is more abundant, (2) there is less competition for nesting space, (3) the climate is milder, or (4) the daylight hours are longer. Why do birds migrate? There are a number of explanations for migration. Migratory birds usually have longer, more pointed wings and weigh less than related non-migratory birds. Migratory birds can build fat stores as an energy source for long flights. Those that do migrate have adaptations not seen in their non-migratory relatives. Two-thirds of bird species found in the United States migrate, some only short distances to more southern states. The more severe the climate of an area, the greater percentage of nesting birds migrate. Do all birds migrate? Not all birds migrate. The migration of most birds is a yearly cycle. It is most evident among birds, which have a highly efficient means for traveling swiftly over long distances.
Migration is often annual and is closely linked with the cyclic pattern of the seasons. What is migration? Migration is the cyclic or periodic travel of an animal as it returns eventually to its original place of departure. What exactly is a Nearctic-Neotropical Migrant?.Why is there an interest in migratory birds in Texas?.How are migratory birds important to man?.How does migration affect the bird life of Texas?.
How does migration benefit birds and the environment?.Do most migrants return after the winter?.What are some human caused hazards for migrants?.How do human activities affect migratory birds?.How is migration coordinated with the seasons?.Are there any ecological implications with migration?.Why do birds fly to specific locations in the spring and fall?.What external factors affect time of migration?.What external factors prepare birds to migrate?.What do birds use for orientation and navigation?.Do birds follow established migratory routes?.
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