I guess Plax this is mostly directed at YOU being as you appear to be our only real live Hyacinth owner.
Yes, luvmytooo also owns a Hy. Hers is a female named Stella.
I have several questions about Hys that you may be able to answer.
1. No question that a Hy has a more powerful beak than even other macaws, but does he use it, I mean does he destroy cages, toys, woodwork etc more than any other macaw?
All I can do is tell you how Zaf is concerning potential for cage damage because I've not spent much time with any Hys other than him.
Zaf has been in each of my 4 cages at one time or another. He has virtually destroyed 3 of them by stressing their bars until the welds popped. The Cal-Cage that Salsa is currently in served as a temporary cage for Zaf several years ago. It's has a one piece frame and it's fairly heavy. Zaf popped 17 of its welds during his last go at it. So instead of taking it to the welding shop, I put it in storage. Since I'm not wealthy, when Salsa's mom (my dear and treasured friend, Terrie) passed away in May, I decided to have the Cal-Cage repaired because I promised Terrie that I'd give Salsa a forever home as well as my unconditional love if she were ever no longer able to care for him.
So, yes, Zaf is hard on cages. One of the 3 he has ruined is a stainless steel cage. Thankfully the panels of the stainless steel cage and the one he's in now are able to be removed for easy repair. The cage he's in now is quite a bit larger than the SS one. So Jack, my B&G, is currently in the SS one. The only cage I have that Zaf can't destroy is my old wrought iron one, since its bars go through drilled holes in its frame. But it's way too small for him.
2. There are supposedly two subspecies of Hyacinths. The smaller ones live in caves in the side of cliffs somewhere in Brazil. The other subspecies is much larger and lives in the top of very tall trees in the Pantanal region of Brazil. Which is yours?
I've read that as well. I'm unsure to which of the two supposed subspecies Zaf may belong. He weighs barely over 1400 grams (empty). At 1570+ grams, Salsa outweighs Zaf by quite a bit. When I look at them together, though, they seem quite similar in size. In another thread, chadwick posted a link to an avian vet's statistical accounting of mean weight per species that shows the 20%-of-mean weight for Hyacinths to be 1170-1430 grams with an average weight of 1301 grams. It shows the heaviest individual of the Hys he has weighed to be 1624 grams. Here's the link to that pdf document:
http://scottemcdonald.com/pdfs/Average Weights.pdf
3. Does your Hy "play nice" with your other birds or does he dominate?
Well, he won't take any guff from them. He mostly tries to stay away from them when he can. Salsa is very jealous of Zaf and presses his buttons whenever he gets a chance. I'm not sure whether you saw the video clip of the fight between Zaf and Sals that I posted. If not, it's here:
http://www.parrotforums.com/macaws/22497-macaw-fight-unintentional-not-wanted-2.html#post184885
4. Do you have a stainless cage for him?
Already answered above.