2007-01-31 06:38:22 · 8 answers · asked by gorgeous 1 in Science & Mathematics ➔ Zoology
They know when to migrate because of instinct. They're born knowing all that stuff. Birds migrate in order to stay someplace warm for the winter. It's easier for them to find food and they don't have to be exposed to freezing temperatures. However, some birds do not migrate south. They stay put during the winter.
2007-01-31 06:42:30 · answer #1 · answered by true blue 6 · 0⤊ 0⤋
How about we get a bit more technical on this for you?
"How do they know when it's time to go? One cue they use is Photoperiodism - this is the lengthening and shortening of days in the spring and fall. Birds have special glands (the pineal and pituitary glands) that are affected by the change in the amount of daylight hours. When the days grow shorter in temperate areas, these glands secrete hormones that make the birds restless and want to migrate. This is called migratory restlessness. Other cues that birds may use to know when it's time to migrate are changes in temperature or rainfall."
2007-01-31 07:27:31 · answer #2 · answered by Yahzmin ♥♥ 4ever 7 · 0⤊ 0⤋
It's part of their instinct. Also you might find it interesting that the environment has alot to do with it. Many birds are flying south later than normal or have fewer mating places because of global warming.
2007-01-31 06:41:55 · answer #3 · answered by Anonymous · 0⤊ 0⤋
I think they see change in the weather patterns and temperature, and they migrate so they don't freeze in Winter or get boiled in Summer.
2007-01-31 07:27:37 · answer #4 · answered by Melody 2 · 0⤊ 0⤋
i dont know how but the reasons why are obvious for a warmer climate and food as the tempture drops the vegatiation and animales they eat are gone so they have to stay in the right climate to feed and breed
2007-01-31 06:43:02 · answer #5 · answered by Anonymous · 0⤊ 0⤋
The weather [heat].
They need pockets of warm air to fly, so when that warmth disppears, in order to stay flying[!!] they need to find heat pockets. Good look! =] =]
2007-01-31 06:46:27 · answer #6 · answered by rosiieish 2 · 1⤊ 1⤋
the weak one will die due to the changing of the weather and that would give clue to the rest to fly south.
2007-01-31 06:41:15 · answer #7 · answered by my alias 4 · 0⤊ 2⤋
It's all instinct, pure and simple.
2007-01-31 06:41:32 · answer #8 · answered by kj 7 · 0⤊ 0⤋