European vulture populations are closely monitored with several methods:

• Rings with different colours and / or codes are used to identify an individual
• Griffon Vultures are additionally equipped with plastic wingtags
• • see details here>>
    
• Some birds are equipped with transmitters, which provided very specific and useful information on their behaviour
• • see details here>>
    
• Each released bird gets some feathers bleached so that it is individually identifiable from far away
• Especially the reintroduced Alpine bearded vulture population is closely followed by an extensive network called International Bearded Vulture Monitoring (IBM).

With all this data, it becomes clear how a population evolves, how successful breeding pairs are, where they forage and what they eat.