I agree with Jelle it is a Dalmatian pelican on the picture.
But I do not agree it is necessary to have 5+ pairs for breeding. The Eastern Whites 4,3 in Prague bred naturaly this year 1 chick. And the Spot-billed 3,2 in Dvur Kralove bred this year 4 chicks (handreared).
I will check my PC - I think I have somewhere pics of unmature Spot-billed pelicans and I will load them to compare.
EDIT: pic