There are many different types of bird migration...

Seasonal This is a movement between breeding and non-breeding ranges. Summer visitors arrive from the south and winter from the north.

Latitudinal This is the migration from northern regions to southern, and vice versa.

Longitudinal Particularly common in continental Europe, this is the movement of birds between eastern and western regions.

Irruptions Irregular migrations are caused by a lack of food and water, resulting in large numbers of birds flying to unfamiliar areas.

Nomadic Like irruptions, these result from a lack of vital resources, but birds cover shorter distances and stay within a familiar range.

Altitudinal This is a movement from high to low ground during the colder months, usually over short distances. Skylarks do this.

Moult During moulting season – often a vulnerable time for birds – species such as shelducks head to safer grounds.

Drift On very rare occasions, migrating birds ‘drift’ away from their normal routes as a result of storms, for example bluethroats in Norfolk.

Reverse This is most frequently seen in autumn when young birds become confused, flying against their expected route.

Dispersal This occurs when juvenile birds are forced to leave fledging grounds to find new territory – it’s not a true migration.