Found this survey ( from 2015 ) on the web and think it may be of intrest. It includes 183 public and 140 privat collections : http://www.wildwaterfowl.org/assets/2015_iwwa_survey.pdf
I find the number of Steller's Eider rather intriguing - just a pity they are nowhere near as common over on this side of the puddle. In point of fact, I am not sure there are any in European private collections at all - there are certainly none in public collections.
Pity that nowhere public is interested in bringing some in, then I have a massive soft spot for sea ducks, to the point that Steller's Eider is one of the few species that I (generally casual in my approach to birding) would actively twitch if one popped up within travelling distance of me.
For several years I lived about 6 miles away from a Steller's eider (Blackbrook). I never made an effort to go and see him.
I didn't know there were any Hawaiian Ducks in captivity. The number of Swan and Greylag Geese seems kind of low.
Lived for about 2 year less then 50 meters from a pair, saw them and took care for them but didn't make pictures of them ( at Pairi Daiza in the mid-1990-ties ).
