Sorensen 1
C.J. Sorensen
Mr. Sorensen
Language Arts 12
12-1-06
Bird Navigation
How much do scientists know aboutmigratory bird navigation?
How do birds know where to go?
How do birds orient themselves in theright direction?
How do the various “cues” work?
What references did you use?
How much do scientists know about migratory bird navigation?
According to the Smithsonian National Zoo Website, scientists know several ways that birds navigate but the results are not always clear. The site states that, “More than 50 years of research has explored many possible mechanisms of navigation from topographical maps to celestial navigation and detection of the earth's magnetic field. It is difficult to get a clear picture of navigation because experimental results for one species cannot reliably be extended to others. Much experimental work on navigation and orientation has concentrated on homing pigeons, a non-migratory species. Most birds probably employ a combination of systems. A bird that normally relies on celestial clues may orient by wind direction on an overcast night. There is still much work to be done in understanding avian navigation.”
How do birds know where to go?
The answer is different for different types of birds. Birds either learn from older birds (usually family members) or they are born with information in their genes that tells them in what direction to fly and how far. Birds such as geese, swan, and cranes move in family groups, and the young learn the route from their parents. Yet, songbirds make their first journey alone so they have to already know where to go. Some birds aren’t even reared by their own parents but still travel like their actual species. It makes sense then that the birds’ navigation is inherited instead of learned. However, once a bird has made a migration genetically it may use learned information as well. The zoo website further explains,“The first migration is completely under genetic control. As birds gain experience, they incorporate learned information. For instance, if they find a particular breeding or wintering location that is good, they mayreturn to this location in the future by relying on learned information” (“Birds”).
How do birds orient themselves in the right direction?
“Although the intricacies of how birds navigate remain a mystery, this much seems to hold true: all migratory birds use a variety of cues, and different species seem to rely on some cues more than others. This can vary according to the immediate circumstances, for example, if it is a cloudy night and the stars are obscured, a nocturnal migrant many[sic] rely more on other sources of information. Other cues used by migratory birds include: the earth’s magnetic fields, location of the setting sun (and the pattern of polarized light created), topographic features of the landscape (coastlines, rivers, mountain ranges, for example), and prevailing wind patterns (wind patterns are seasonal; during migration the wind tends to blow in roughly the appropriate direction for migration).”(Deinlein)
How do the various “cues” work?
Birds use three primary cues which Ornithology professor Margret Rubega calls compasses.
“Birds can use the sun, the stars and the Earth's magnetic field.
- Birds use the sun as a compass. They use the positions of the sun during the day to navigate. They also can use the setting sun as an indication of due west.
- Night flyers use celestial navigation, which means they find their way by knowing the patterns of the stars in the sky, and by knowing special stars like the North Star. In their first year of life, birds memorize the position of the constellations in relation to the North Star. These star patterns stay the same even though the Earth moves through space, making the constellations appear to move to different spots in the sky during the year.
- Birds have tiny grains of a mineral called magnetite just above their nostrils. This mineral may help them to navigate using the Earth's magnetic field, which tells the bird what direction is true north.”
What references did you use?
“Birds: Frequently Asked Questions.” Smithsonian National Zoo
Deinlein, Mary.“Neotropical Migratory Bird Basics.”Migratory BirdCenter: Smithsonian National Zoo. < default.cfm?fxsht=9
Rubega, Margreet.“Lecture 14: Navigation.” Lecture Notes.
Scanlan, Kerry, Vicki Piaskowski, Michelle Jacobi, and Steve Mahler. Bird Migration Facts. Zoological Society of Milwauke. ASF/Library/BirdMigrationFacts.php