Please note, I am not any kind of expert on bird health, so don't take my word on anything with out researching further/ talking to vet.
Calcium requires D3 to be absorbed. Donovans bird, if I remember correctly, spends time in an aviary, so would be receiving suffiencent d3 over the summer months.
The calcium requirement for a male bird is very different from that of a hen in breeding season.
I believe it can be detrimental to give too much calcium.
This article may be helpful
http://www.multiscope.com/hotspot/health1.htm I haven't read the whole thing, but the bit about calcium follows what I have read elsewhere.