====== Bird Migration ======

Around 50% of birds migrate (i.e. undertake large-scale routine long distance travel for breeding / feeding).

The distances covered can be huge - e.g. //Manx Shearwaters// migrate 14,000 km (8,700 mi) each year. The time-triggers, and the methods of route navigation, have been widely investigated, but much of the detail is still unknown.

See: [[https://en.wikipedia.org/wiki/Bird_migration#Long-distance_migration|Wikipedia]]

It //is// known that birds use a variety of methods - magnetic fields, star positions, odours etc, and some species are 'taught' navigation routes by their parents and peers. But others, e.g. the [[https://en.wikipedia.org/wiki/Marsh_warbler|Marsh Warlbler]] are hatched with built-in mental 'maps' - and an acute 'diary' (i.e. timing) system. How these systems operate, and the way that this information is somehow encoded into their genes is entirely unknown.

A BBC audio discussion on the phenomenon can be found here : [[https://www.bbc.co.uk/programmes/b08wmk5j|In Our Time, June 2020]]

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Also see : [[content:life_sciences:zoology:pigeon_navigation|Pigeon navigation]]  and   [[content:life_sciences:zoology:turtle_migration|Marine Turtle Migration]]  and  [[content:life_sciences:zoology:monarch_migration]] and [[content:life_sciences:zoology:sardine_run]]