Verifiable endangerment of a species or ecosystem that is part of the commons of a community is aggression against any non-consenting member of that community. Persons must refrain from inflicting intentional cruelty on sensate beings, and respect their freedom in proportion to the cognitive capacity of their kind.
Prop 2 just passed in California, giving farmers until 2015 to eliminate the confinement of "pregnant pigs, calves raised for veal, and egg-laying hens in a manner that does not allow them to turn around freely, lie down, stand up, and fully extend their limbs." The LPCA ExCom had approved a motion opposing the measure, over my lone dissenting vote of "neigh". The LP ought to get ahead of the curve here, but we aren't yet institutionally capable of thinking in the shades of gray required by franchise issues like animal rights. We barely have a handle on children's rights, and have never coherently addressed the rights of the unborn.
Last year Spain became the first nation to extend some individual rights beyond humans. It did so by adopting provisions of the 1993 Declaration on Great Apes: www.greatapeproject.org/declaration.php
For a summary of various declarations of individual rights throughout history, see libertarianmajority.net/bills-of-rights-archive