Fascinating Facts About Migratory Birds

Fascinating Facts About Migratory Birds 

Arctic Terns

Bird Migration is a worldwide phenomenon that happens for many varied reasons.Temperature changes, seasonal fluctuations in food supplies, breeding needs, and territorial considerations all play a role in the why of migration.Routes vary from species to species, as well as from individual to individual. How routes are found and followed is a fascinating aspect of this yearly pilgrimage that scientists are exploring.

Birds are well-known for their migrations, but butterflies, salmon, turtles, toads,caribou, lemmings and whales are just some examples of other animals which make migrations with the seasons. These animals travel seasonally along specific routes and move to areas which are seasonally beneficial to them because of the inherent needs of the species (such as breeding ponds or mild weather and abundant food).

1. More than 200 species of neotropical migratory birds nest in North America. These birds breed north of the Tropic of Cancer during the North American summer and spend the North American winter in Mexico, Central America, South America or the Caribbean islands.


2. Prior to migration, birds transform themselves into "super birds." The secret is eating, eating and more eating. A bird can accumulate fat reserves up to 50% of body weight in preparation for departure. The blackpoll warbler (Dendroica striata) does not eat candy bars, but a candy bar containing 14 grams of fat has 1½ times the energy needed to fuel this bird's flight from the northeastern United States, over Barbados and on to South America.


3. Most migrant birds have longer, more pointed wings than non-migratory birds. This "pointed-edge" design helps to reduce air resistance during prolonged flights.


4. Ninety percent of birds fly an average of 25-70 kilometres per hour during migration. The flight speed depends on the species of bird; for example, songbirds fly at 15-50 km/hr and waterfowl at 50-80 km/hr.Tailwinds blowing in a bird's direction of flight increase air speed, while headwinds decrease air speed.


5. Most migrating birds fly at an altitude of 150-4,000 metres. Like airline pilots, birds choose a flight altitude based on the best wind conditions. A high-flying duck holds the record (posthumously) for the highest flight altitude for a bird in North America. It collided with an airplane at 6,400 metres.


6. MAGNETIC FIELD DETECTION:  Some birds use the Earth’s magnetic field to help them navigate during migration.


7. A built-in compass helps birds to navigate during migration. In addition to the sun, the stars and earth-based landmarks, a migratory bird's brain contains microscopic crystals of magnetite, an iron-based mineral. The ancient Chinese used magnetite to make the world's first compasses. This mineral enables birds to create a mental map of the flight route.


8. WEATHER & OCEAN CURRENTS:  Weather plays a huge role in bird migration.  Not only do storms bring accidental bird visitors to foreign shores where they never intended to go, but birds also use prevailing winds and rising thermals as migratory aids.


9. SMELL, SIGHT AND SOUND:  Birds also use smell and sound to help them migrate.  These may play a larger role when the bird arrives near its destination.Using its sight, hearing and sense of smell to find a specific location.  Sounds such as other bird calls, frogs, highways, surf, and wind can be important signals when a bird is searching for its nesting area.  The smells of salt marshes, certain plants, or the strong smell of guano of a bird colony can be unmistakable.  Landmarks such as tall trees, cliffs, buildings, steeples, highways, headlands, and beaches are also clues to finding a specific spot.


10. STAR COMPASS:  Many species of birds migrate after dark.  How do they find their way when the ground landforms are less evident?  Some may use magnetic field detection, or smells and sound.  Some may use stars.


11. Most migratory birds travel in flocks, a common English-language bird word, but the broad-winged hawk (Buteo platypterus) migrates in kettles. As these hawks soar on high-altitude thermal currents, their swirling or "boiling" .flight behavior is called kettling -- it resembles bubbles boiling in a teakettle. According to another kettle-name theory, the hawks' in-flight swirling is similar to chopped vegetables (carrots, some say) bobbing in a kettle of boiling soup. Most broad-winged hawks in the Caribbean islands are year-round residents, but migrants from North America supplement local birds.


12. The green-winged teal's is truly special. It is the only known species of migrating duck that scratches while in flight. This beautiful (and itchy) duck, Anas crecca, also scratches while feeding and resting at Graeme Hall Nature Sanctuary.