Some birds are partial migrants, because only a portion of their species will migrate in the winter. There are also irruptive migrants who travel occassionally but not every year, and some birds don’t migrate at all.

Preparing for a long journey

Taking such a long journey requires a lot of energy, so birds eat an abundance of food to gain weight. The fat becomes fuel for flight, keeps them from starving and also insulates them from the cold.

Finding the way

Year after year many birds use the same migratory pathways. In addition to a compass-like instinct, they use many guides to find their way. These guides include: topography, geography, the direction of the wind, the position of the sun, stars and moon. Certain sites can act as barriers, such as bodies of water, deserts and mountain ranges,or sometimes as leading pathways.

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