I don't agree with sending animals away, or closing exhibits for financial reasons. I believe costs should first be cut in other areas, such as management, administration, fundraising, conservation, education, somewhat in that order.
I don't particularly like the idea of moving animals around for breeding purposes, either, unless there is definite, imminent danger of their species becoming extinct, and there is absolutely no other way to restore the population.
Of course, I don't object to sending animals to other zoos IF the animals are not doing well and another zoo could provide a place where they would do well, or if the home zoo has an excess of one kind of animal and another zoo has none, etc.
You also stated "the majority of this money [spent on conservation] comes from research grants that cannot be spent on operating costs, this money would be given to ther scientific research if it wasn't used for animal research." I am very much in favor of using grant money or donated money to conduct on-site animal behavior research, particularly research that zoo visitors can observe and learn from. I am NOT in favor of any of the zoo's money going to off-site research or conservation projects.
So the Philadelphia Zoo is the best. At least that's my opinion.
Wow. Where to even start. First off, the world financial situation has resulted in the Bronx Zoo laying off or accepting early retirement of nearly 200 people, including management. The cost of keeping animals, per se, is only a fraction of the cost of operating a zoo--the vast majority goes to pay people. Some of whom care for the animals or maintain their facilities. So when you lose more people than many zoos employ in total, something has to give--i.e. exhibits need to close.
Many donors to zoos give money ONLY because zoos are engaged in conservation. If zoos stop funding that work, many of those donors will stop giving. But beyond that, zoos can and must provide expertise needed to help manage declining wild populations, which more and more are like zoo populations, requiring veterinary care and other "zoo-like" management. Who better to provide this than zoos?
But most curious of all is your continued insistence that the Philadelphia Zoo is "the best" (or even good). The tile bathrooms of the "Rare Animal" building, the Auschwitz-looking hotwire barriers in "Bear Country," the ancient rhino, elephant and hippo yards, the brutal rockwork lumps of "Carnivore Canyon," the ridiculous "logging camp recovered by nature" theme of the Primate House--it all adds up to me as a confused and space-challenged old zoo fighting to barely stay afloat. And at $18 dollars a head, one of the worst values of any major zoo in the country.