As my thought has progressed and matured over the last few years, and the longer I have studied philosophy and law (specifically the nature of rights), I have become more and more convinced that all non-human animals have no rights. This is a near 180 from the position I held as a teenager and younger 20-something.
I found it difficult to specify why I oppose the notion of animal-rights without sounding unnecessarily cold-hearted, but this website I stumbled across does sum up a lot of how I feel:
http://www.aynrand.org/site/News2?page=NewsArticle&id=7987&news_iv_ctrl=1084 "We must wage a principled, intellectual war against the very notion of "animal rights"; we must condemn it as logically false and morally repugnant."
This site, too, I find agreement with:
http://www.objectivistcenter.org/cth--391-FAQ_Animal_Rights.aspx "The value a person receives from other people depends on their freedom from physical force. However, the value a person receives from animals depends on their lack of freedom from physical force. While a person receives food, clothing, and medical knowledge from other people by allowing other people to freely produce these things and trade them, a person receives food, clothing, and medical knowledge (through research) from animals only through force. Moreover, disputes with animals cannot be resolved with discussion or the threat of legal sanction, as they can be with other people, and so to prevent animals such as lions, rats, and cockroaches from attacking a person's person or invading a person's property, his only option is to initiate force against them. This is why a person should refrain from initiating physical force against other people but not against animals, and this is why people have rights and animals don't.
I find that a lot of people who advocate animal rights have little to no philosophical or legal training and do not understand what a right is in the first place or how important concepts such as rights really are.