Migration Birds

Bird migration — the seasonal movement of birds between breeding and wintering grounds — is one of nature's most spectacular phenomena. An estimated 50 billion birds migrate annually; many fly extraordinary distances: the Arctic tern migrates from the Arctic to the Antarctic and back (70,000 km annually — the equivalent of 3 round trips to the Moon in a lifetime); the bar-tailed godwit flies 11,000 km non-stop from Alaska to New Zealand (the longest non-stop animal migration). Birds navigate using multiple systems: magnetic sense (detecting Earth's magnetic field through cryptochrome proteins in their eyes); star navigation (using the night sky); landmark recognition; and smell (albatrosses navigate by smell over featureless ocean). Climate change is disrupting migration timing (phenological mismatch) — birds arrive at breeding grounds to find peak food availability has shifted. Light pollution disrupts magnetic navigation; billions of birds die annually from building glass collisions.