Bird migration
Bird migration is a fascinating phenomenon observed in various species worldwide. It refers to the seasonal movement of birds from one region to another, typically covering long distances. Migration occurs in (1)___________ to changing environmental conditions such as temperature, food availability and breeding opportunities. Some species of migrating birds travel (2)___________ distances each year.
The Arctic tern is the seabird which holds the record for the longest migration route, travelling from its breeding grounds in the Arctic to its wintering grounds in the Antarctic. This round-trip journey (3)___________ over 44,000 miles, as these birds do not follow a straight course but take advantage of prevailing winds.
Ruby-throated hummingbirds, found in North America, are tiny creatures which (4)___________ a migration covering approximately 2,000 miles. What makes this journey impressive is that they navigate across the whole Gulf of Mexico in a non-stop flight.
However, the bar-tailed godwit, a wading bird which breeds in the Arctic, has the longest non-stop migration route of any bird species. (5)___________ some individuals fly over 7,000 miles from Alaska to New Zealand across the Pacific Ocean in a single flight that can last up to eight days.