TV's Frink said: Probably something about people who hunt but oppose any kind of abortion in any situation, but I don't remember now.
Just to be clear, I don't hunt.
As for those that do, their rational is probably this:
human > deer
human embryo = human fetus = human
therefore:
human embryo > deer
human fetus > deer
therefore:
it is ok to hunt deer, but not abort human fetuses or human embryos.
Just to play devils advocate:
those that hunt might question the logic of those that complain about those that hunt and yet have no problem eating meat.