I don't mean to jump on anyone's case, but just thought I'd give my own input. In my opinion, Clfsean is correct. The different animals have very specific approaches to fighting, and it goes far beyond the type of hand strike they use. A Crane method is much more than simply using a cranebeak strike, and a Tiger method is much more than simply using tiger claws. In fact, the different animalized hand strikes can certainly be found within other animal methods. We use a tigerclaw in Tibetan White Crane system, for example.
I think what Clfsean is getting at is the approach used to create an effective animal method. The animal has characteristics. It has strengths and weaknesses, and a certain approach to fighting that is relatively unique, compared to the other animals. Training methods are used to develop the skills needed to take on this approach, and deliver the strikes appropriately. So for example, if you are using a Crane method, it really does not make sense to try to blend tiger with it. Of course you can switch from one to the other, but Crane method doesn't work if it is half tiger. If you are going to use tiger, then switch to tiger. Otherwise, keep doing crane.
I am a believer that in a real fight, chaos reigns and this often means your technique gets switched up and used differently from how you learn it and train it in the "ideal" phase. But if you are using a specific animal methodology, you stick to that methodology, regardless of how the individual techs get mixed up.
Here is another example: Tibetan White Crane is just about as different from Wing Chun as it is possible to get. I bring this up because Wing Chun was part of the initial post in this thread. Anyway, the power generation is entirely different, technique execution is entirely different, footwork and stancework are entirely different, approach to fighting is entirely different. I know this because I have studied both. If I used Wing Chun as a platform to fight from, but tried to mix in White Crane hand techs, it would fail miserably. It is the footwork and stancework and approach to fighting that White Crane uses, that makes its hand techniques effective. To try to graft those techs onto Wing Chun, takes them out of proper context, forces them into a context that doesn't make sense, and they would be worthless.
So getting back to the point: trying to force animal characteristics onto something that isn't animal, or onto something that is a different animal, just doesn't work well, and it doesn't suddenly make that non-animal thing into an animal thing. Simply using "animal" hand strikes doesn't make something an animal system. Substituting a tigerclaw for a punch doesn't make it tiger. Under the right circumstances, the substitution might be effective, but it remains just a substitution. It's not truly "tiger".
Hope this helps.