Migratory Birds Are the Original Inventors of GPS Systems and Heads Up Displays
My Birds Are Coming Home Soon!
Spring is a wonderful time when the Earth begins to yawn and stretch. She turns over and hits the snooze button several times before getting up, and that's why March is such a crazy month here in the Northeast! One day it feels like spring has arrived, the next day we have 3" of snow covering the crocus. Soon, though, she will decide it is time to begin her morning. And that's when we'll start to see our birds arriving from their southerly homes.
I know they have flown thousands of miles to come stay with me for the summer. So I make sure my bird feeders are well stocked. They'll be hungry and tired, and searching for a meal is the last thing they need to do after that arduous journey.
Noting the date of each bird species' arrival helps me to determine when bird houses should be cleaned and in place ahead of time for this year's new generation. You can find birding festivals in your area, which are held at peak migration times. It's a fun family outing to attend a migration event. Make sure you bring your binoculars and or camera. You might be pleasantly surprised to see birds you've never observed before!
Completing Their Journey Takes Strategy
Birds fly high up in the atmosphere where there are no obstacles to distract them or slow them down; the air is thinner helping them to fly faster using less energy. They take advantage of updrafts and fly in the wake of another bird's air stream, much like race cars use ‘drafting’ off another car to increase their speed. This strategy allows birds to use less effort so they can coast at high speeds and actually rest while flying.
That's why geese take turns at the head of the 'v' formation; the leader does all the work for the flock that follows. After that bird becomes tired another takes over. In this way they can all work together, which uses up the least energy while propelling them all forward at a much faster rate than if they were traveling singly.
Bird Migration Across Chicagoland
How do birds find their way?
Birds use all their senses to navigate. Having a road map, or more accurately a terrain map in their heads, they take visual cues from the well-traveled migration routes established over time. Perhaps they followed in their parents' air stream when they were young. That memory is still ingrained in their brain, along with any smells and or sounds associated with the migration route.
So What Are These Built-in Bird GPS Systems and Heads Up Displays?
The latest findings indicate birds use not only the sun, moon and stars to navigate just as ancient mariners, but they have what corresponds to a navigational map that uses Earth's magnetic fields.
It seems that the eye and beak of a bird hold the secret to this navigational map. Their retinas contain pigment molecules, which when stimulated by light of a certain wavelength trigger a magnetic navigational mechanism. This generates a visual 'display' which is superimposed on their visual field. Birds can then use this to determine their direction based on that magnetic information system. It is in effect their own magnetic compass. This is not to be confused with our well-known compasses, which rely on polar magnetic fields. They can fluctuate often and therefore would not work well for birds' navigational purposes.
But there is still another magnetic mechanism that is motivated in response to the behavior of iron oxide, also known as magnetite, which can be found in the outside layer of a bird's beak.
According to Birdwatchingdaily.com, April 2012 issue, this substance helps them to orient themselves depending upon the strength or weakness of the magnetic fields generated by the Earth. When the intensity of the magnetic field changes, the magnetite moves, sending an impulse to a large facial nerve. This impulse is sent on to the brain stem where certain cells process the magnetic map information. The theory is that a bird uses this information to create and remember a 3D version of the space in which it lives and moves. Sounds like science fiction, but birds are amazing creatures we have yet to truly understand.
Scientists have long wanted to unlock this secret world of birds' ability to return to virtually the same spot every year after traveling thousands of miles. Homing pigeons are the most famous examples. Even when released in an area where they've never been before, they can still find their way back to their own dovecote. Now we are finally beginning to understand at least some of birds' internal GPS (global positioning secrets)!
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The Journey North Spring 2013
- Journey North Spring 2013
A wealth of information about birds, butterflies and other wildlife and when they migrate; plus many other facts and useful info about hummers, birds of prey, waterfowl, robins and more.