These are my incomplete ramblings on an idea I intend to come back to soon.
Anti-speciesism exists as a rejection of the specific dominant morality that suggests humans are “higher” or more important than other animals, or at least that's my understanding of it.
It seems that many of the arguments in favor of speciesism center around who should be a part of the “moral community”.
This wikipedia entry is pretty interesting and lays out more of the debate. In the entry Paola Cavalieri directly aligns species membership with moral membership and points out that even for seemingly human animals species membership is often conditional. Likewise, the many critiques of humanism can be drawn into this discussion and perhaps anarchists would do well to familiarize themselves with them.
Still, even for those of is who oppose a speciesism, it makes no sense to extend an entirely human derived morality outwards to critters that have no interest in it, and who are inherently incompatible with the interests of morality. Killing is a common occurrence in wild nature, and does not fit into human morality without coding behavior along species lines and saying something like “killing is fine if wolves do it” which just returns us back to square one.
So, if we want to interact with all critters the same as we do each other I think we instead have to make individualistic valuations based on our own needs instead. That last part was the egoist in me, but perhaps there's different answers out there.
Basically cats don't want to wear pants and bears will kill you but there is no generalizable “right” or “wrong” in how they act, and the same goes for human animals. I'll wear pants if it's cold but otherwise maybe I won't, not because morality says so.