As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Friday, 14 September 2012

COLLINS: When do birds migrate for winter?

More than 300 bird species found in North America during the summer will make their way to Latin America or the Caribbean for our winter months, some covering distances of nearly 7,000 miles. Parks, backyards, and nature refuges across the country will host these winged visitors for the next few weeks as the birds make their way to their fall and winter destinations.

Migration is a fascinating feature of bird behavior. Besides the amount of daylight, it appears that age, sex, weather conditions, and the availability of food, water, and shelter are the major factors that influence migratory behavior.

While migration is still not completely understood, it appears that some birds orient themselves by the stars on clear nights while others seem to have a built-in magnetic compass. Some birds travel over large bodies of water, and in doing so lose one-fourth to one-half of their body weight. In order to survive this grueling trip, birds accumulate fat prior to migration. This physiological change helps the birds maintain their energy reserves.


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