Are gay marriage and homosexuality okay because there are gay animals?

The argument by gay rights supporters for the acceptance of homosexuality and same sex marriage is the following:

Gay rights reasoning:

Premise: Humans have a conscience.

 Premise: Wild animals do not have a conscience.

Premise: Immorality only can exist if a person has a conscience.

Inference: Animals (or at least most) do not have a conscience, therefore their behavior is morally neutral.

Conclusion: Therefore, a human mimicking animal behavior cannot be immoral, since the same behavior is not considered immoral when done by a wild animal.

and/or:

Premise: Only humans can be immoral.

Premise: Behavior observed by animals in their natural habitat cannot be morally objectionable

Premise: Homosexuality occurs in nature in several species. 

• Evidence: It has been observed in animal species. http://www.news-medical.net/news/2006/10/23/20718.aspx

Conclusion: Therefore, homosexuality among human beings is natural and gay marriage should likewise be accepted and legalized, since wild animals practice it and they cannot be immoral.

However, if these conclusions are to be accepted, likewise the following argument should be accepted.

Premise: Only humans can be immoral.

Premise: Behavior observed by animals in their natural habitat cannot be morally objectionable

Premise: Rape occurs in nature in several species. 

• Evidence: It has been observed in several animal species.http://news.bbc.co.uk/2/hi/science/nature/7379554.stm

Conclusion: Therefore, rape among human beings is natural and rape and rapists should likewise be accepted and legalized, since wild animals practice it and they cannot be immoral.

 The same argument and conclusion can be reached with infanticide, paedophilia (book by 'atheist' Richard Dawkins), war, kamikaze/suicide 'bombing', polygamy, cannibalism, and several other strange things.

Will supporters of homosexuality likewise support these behaviors? Of course not. The "because animals do it argument" falls on its face since they refuse to let the sword cut both ways.

However, they might rebut that you cannot compare them since homosexuality is between 2 consenting parties. To which it should be noted that incest, polygamy and sometimes suicide can also be done with consent. So, the argument should have nothing to do with animals what so ever.  Furthermore, why should more developed, more intelligent animals mimic behavior of lower animals? Isn't that NOT "forward thinking" and "backwards"?

NOTE: The video was TAKEN DOWN by youtube censors for 'hate speech' (several years later)!