There is a very good organization, EARS (Emergency Animal Rescue Services) that I don't support directly (See below the fold for my support strategy). Why? The parent activism group, United Animal Nations, is too close to the animal-rights movement. What is the difference? There's a dedicated blogger that covers the excesses of the animal-rights movement, Brian O'Connor who writes at Animal Crackers.
Animal Rights is premised on a couple of beliefs: first, that the life of an animal and that of a human are of equal value. Second, that any exercise of control by humans over animals is sinful. In short, if it is immoral or unethical to do something to a human, it is likewise unethical or immoral to do it to an animal.
These considerations trump the survival of a species, or the health of a habitat. For example, Animal Rights activists believe it is morally preferable to allow an entire habitat to be destroyed by deer overpopulation than for humans to cull deer by shooting some of them, even if by leaving the deer population alone many of them starve to death, and cause the deaths of other animals whose habitat the deer destroy.
....Animal Rights activists define being kept in a zoo as cruel (animals and humans are of equal value, and if it's immoral to keep a human in a zoo, it is to keep an animal in a zoo . . .), and would prefer to see [zoo animals] .... released into the wild regardless of the consequences to the [animals] the survival of their species, or the consequences to habitat they might be released into.
It's a matter of ideological purity . . .
If any of you are interested in domestic terrorism, do follow Animal Crackers. Dr. O'Connor has the goods.