Yes, it is still taking a life. Unfortunately, one type of taking a life is bad, and the other is not bad.
A natural right, great. Why do they have this natural right?
No, I have a right to life because of my rationality, and because I can grasp the concept of mutual respect of rights.
They're not really rational, they're about as intelligent as a two year old, and they won't necessarily respect my rights, or each others.
Also, monkeys don't speak a language.
Your entire point seems to be based around, "They don't have a right to live because they don't respect my rights. They don't respect my rights because they were born that way." If this is the case, then the way they were born gives others the right to kill them.
Now THAT is ridiculous. That's like saying that if your child was born blind and deaf, it gave someone else the right to kill it. They do not respect that persons rights, because they can not understand them.
Which brings me to my question. What rights are you expecting a deer to respect, in order for it to be deemed worthy of living?
Surely, since a monkey isn't rational, and has the intelligence of barely a two year old, and therefore it would be no harm for one to simply die, then a two year old baby isn't rational, and has the intelligence of that his/her age, and therefore it would be no harm for one to simply die. Unless you decide to bring up the old, "Well, that baby can grow and learn to respect my rights, as a monkey cannot.".
This would not be a good argument on your part because it would mean that the time in between being an infant, and that which that baby can learn rationality, and learn to respect rights .. In between those two periods, it isn't worthy of living. <--Sorry, kind of an irregular runon sentence. Ah well.
Oh, and monkey's don't speak a language recognized by any human. One monkey can, in theory, communicate to another monkey. They don't use hand symbols, and it hasn't been proven that they can speak telepathically, so the only other option is a language.