How & why

Why are spoonbills being ringed?

Spoonbills in particular have been color-ringed in the Dutch breeding colonies for over 40 years. The reading of the color rings is done by more than a thousand dedicated volunteers. Data on these color-ringed spoonbills are stored in a database, in which data is managed by the working group since 1972. The Dutch Spoonbill Working Group also manages data on spoonbills ringed in Belgium and Germany and collaborates with other ringing groups within Europe and out there. In addition, part of the spoonbill young of the subspecies balsaci in Mauritania is color-ringed.

After a number of years, we were able to start calculating with these data. For example, it appears that survival depends on population size. The reason for this is probably competition for food. Survival clearly decreases as spoonbill numbers increase. Moreover, survival strongly differed between adults and juveniles. Survival of juveniles is the lowest, with most juvenile mortality occurring after the breeding season, on their first journey southward. Adults experience highest mortality on the way back from West Africa to the Netherlands. Resightings in winter showed that there is a shift going on from wintering in West Africa to the Iberian Peninsula, and survival of spoonbills wintering in Europe is higher than of birds wintering in Africa.

Sometimes people wonder whether further research is still necessary, for example with the argument “we already know everything”. First of all, there is a lot we still don't know, but also the current situation may change, an example of this being the recent shift of the wintering distribution from Africa to Europe. Long-term colour-ring research provides invaluable data on, among other things, (changes in) survival, age structure, migration strategies and habitat choice.

How we ring the spoonbills

Studio Brandaris made two videos in which it’s explained how we ring spoonbills.