Bird Migration

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Nearly everyone, especially birders know many bird species migrate.  How much do you really know about migration? Some bird migration facts are surprizing. The word migration comes from the Latin migratus that means “to change” and refers to how birds change their geographic locations seasonally. Ten interestin gfacts about bird migration in Wisconsin.

 

1. Migration peaks in spring and fall, but birds in Wisconsin are migrating over 330 days a year. The actual dates of when birds migrate depends on many factors, including bird species, migration distance, travel speed, route, climate and more.

2. Before migrating, many birds enter a state of hyperphagia, where hormone levels compel them to drastically increase their body weight to store fat to use as energy while traveling. Some bird species may as much as double their body weight in the weeks leading up to migration.

3. The time it takes a single bird to complete its one way migration can range from a few weeks to up to four months. Birds migrating late in the season typically travel faster than earlier migrants of the same species.

4. Hawks, swifts, swallows and waterfowl migrate primarily during the day, while many songbirds migrate at night, in part to avoid the attention of migrating predators such as raptors.

5. The cooler, calmer air at night also makes migration more efficient for many species, while those that migrate during the day most often take advantage of solar-heated thermal currents for easy soaring.

6. Migrating birds use the stars for navigation, as well as the sun, wind patterns and landforms, all of which help guide them to the same locations each year. The earth's magnetic field also plays a part in how birds migrate.

7. Birds may fly from 15-600 miles or more per day during migration, depending on when they are migrating, how far they have to go and the conditions they face along the route, including the availability of suitable stopovers.

8. Many migratory birds have longer, more pointed wings than nonmigratory species or birds with shorter migrations. This wing structure is more aerodynamic with less air resistance and allows for more efficient, easier flight.

9. Migrating birds travel at speeds ranging from 15-50 miles per hour depending on the species, flight pattern and prevailing winds with most species in wisconsin flying lower than 2,000 feet.

10. The ruby-throated hummingbird migrates from the Yucatan peninsula of Mexico to the southeastern United States every spring, a journey of 500-600 miles over the Caribbean Sea that takes 24 hours without a break.

 

Important migratory bird habitat seldom visted by birders includes:

• Dune systems along Lake Michigan - LeConte's Sparrow are regular vistors to Chiwaukee Prairie in Kensoha County.

• Short-grass habitat in Lafayette and Grant Counties - Sandpiper species, such a American Golden Plover, Pectoral Sandpiper, Baird's Sandpiper, Upland Sandpiper and formerly, Long-billed Curlew use these surrogate prairie habitats much more than mudflats.

• Bluff praires along the Mississippi. lower Wisconsin and Lower Chippewa Rivers are magnates for migrating warblers. Spring hatches of insects, combined with the early morning warmth of these peaks are a draw for migrants needing that breakfast pick-me-up.

• Large river floodplains have the most food availability and thus the highest number of migrants. Interior access to vast floodplains is a daunting proposition for many birders, but for those few who can navigate the wild, the rewards are outstanding.

• Large sedge meadows with natural vegetation (not reed canary grass) can harbor migratory numbers of Yellow Rail. A visit from between 2 to 4am provides the birder with the best opportunity to hear these secretive rails.

• Open barrens and dry sandy prairies harbor surprising numbers of sparrows and many species more commonly found in western United States find refuge there. 

• Deep water portions of the Great Lakes can occasionally amass great concentrations of species such as Long-tailed Duck, Red-throated Loon and scoters.