The thing that is not quite clear to me for this scenario is if there is coordination or not. It’s clearly not a realistic scenario in the first place, but what are the rules exactly? Did the aliens provide coordination between the animals beyond saying “go kill humans?” In the extreme, all animals would be used as remote controlled weapons by the aliens, which I don’t see humans surviving especially if that extends to microscopic life.
From the OP:
Edit: love the username/topic combo.
Oh well never mind then. I should learn to read one of these days.
Well, yes. But if they all decide at the same time that their primary food (or for herbivores, enemy) are humans, isn’t there just a constant and universal attack going on throughout their waking hours either for the full 31 days or until the unsuccessful ones die of hunger?
So no, there’s no General directing strategic initiatives (like the squirrel/corn example) but there would certainly be a group attack at any time by any animals in the neighborhood.
By assigning humans as threats or meals, what’s meant? Almost every wild animal already regards humans as a threat and/or as a meal. A squirrel sees us as a threat; a shark sees us as a meal; a mosquito sees us as both. Is the change only occurring with domestic animals?
If the idea is that animals regard humans with suicidal hatred, that might change things. Otherwise, I’m thinking that we get a lot of deaths from dogs and cats, we get mass euthanasia units, pets are outlawed for the foreseeable future, and we start building up our space defense network.
I guess to make it work you gotta add “suicidal hatred” to the mix.
So no co-ordination, but lots of anger and unwise-from-an-evolutionary-POV attacks - every rat you see (or rather, that sees you) wants a piece of you, but they aren’t acting in concert, that kind of thing.
I predict that this will only make a seriously noticable difference as you go up the chain of complexity to higher animals. Micro-organisms either already want a piece of you, or don’t have the capacity to really notice you; insects are in more or less the same boat - even if a colony of ants hated you with passion undying, without a directing force they are unlikely to be able to find/follow you. Bees and wasps would be a pain, and would get a few; going outside would risk clouds of flies.
You’d get mobbed by birds if you went out, and of course rodent attacks, but comming at you individually. Larger animals would do some damage, but other than pets, there just aren’t many of 'em where people mostly live.
I would bet that it would seriously deplete the world’s population of zoophiles. 
Pet owners would be a hard hit subgroup of early victims due to proximity. Most of the time, I am pretty sure my cats are one missed meal away from eating me as it is.
Otherwise, most concentrations of humans are pretty far removed from really dangerous animal populations. Adding in the arachnids and reptile would complicate things most, especially in areas that are already high in venonmous populations. Sorry, Aussie dopers. 
I seem to remember participating in that thread…and I just have one thing to say…
I think all you people with big dogs would be the first up against the wall. Me and my gecko will be safe, I think.