Initiated by Hans Christian Cornelius Mortensen in 1899, the ringing of bir
ds unveiled some of the mysteries of avian migrations, notably routes and d
estinations in migratory species. Using a few case studies, the paper prese
nts an overview about the evaluation of migration routes. It exemplifies ho
w recoveries of ringed birds were used to delineate the species and populat
ion specific migration routes, differences in migratory behaviour between s
exes and age groups. Ringing also played a significant role in orientation
and navigational studies, and it helped to illuminate micro-evolutionary as
pects in avian migration. However, the analysis of recovery data is affecte
d by considerable biases and pitfalls owing to variation of reporting rates
in space and time. Proper statistical models are needed to analyse movemen
t patterns and their variations. Recently, new tools such as satellite tele
metry emerge enabling more sophisticated studies of migration. Nevertheless
, ringing of birds continues as a unique and essential method, even for mig
ration studies. More than ever before, however, ringing in bird migration s
tudies requires international collaboration and co-ordinated continent-wide
and long-term studies both for basic science as well as for the effective
protection of migratory birds.