Despite what Disney and PETA would like you to believe, the wild is not all fun and games, and those that live there are not sweet, innocent, or nice by any means. While a human may stay his hand, animals have no sense of mercy. If they have the desire and ability to kill you, they will.

Animals in real life are far from their romanticized versions. The oh-so-noble eagle will steal food from other birds, and has no qualms about eating carrion. Dolphins will kill for pleasure. Wolves will gang up on and kill coyotes and even other wolves. Horses treat their females like crap. Watch some PBS or BBC. They tell it like it is. Give an animal like that intelligence and the ability to talk, and you have a predator that is not only faster and stronger, but just as smart (or smarter). Research your target animal's behavior and then build its personality off of that. A trapdoor spider would likely be very patient and calculating, while a dragonfly would probably be more fun-loving, hyper, and confident (but still extremely vicious).

Now, there's nothing wrong with an animal being human-like. If a talking wolf has become revered by humans, accepted into their society, and (most importantly) fed, then that wolf may lose its animal instincts and become part of human society. Even so, it should retain some of its old characteristics. If it gets injured badly enough or doesn't get fed, it would probably revert back to its old ways.

Sometimes, talking animals (especially if they're some kind of companion to the hero) are used to pound in a poorly-constructed and blatant message about environmentalism or "acceptance". Fine. I can live with that. But, on the topic of acceptance, talking animals in fantasy seem to fall into the trap of charismatic megafauna. The gift of speech only seems to be granted to "majestic" or "cute" animals, like wolves, bears, birds of prey, snakes (very rarely, and most of the time they're evil), horses, songbirds, dogs, and cats.

Why not less glamorous animals? I don't think I've ever seen a talking dung beetle, or a talking wild boar. Heck, there are a lot of interesting animals out there, but not many of them are ever given page-time, or a speaking role. 

1. Shrikes. These guys are the Ozzy Osbournes of songbirds. They don't just kill and eat insects, smaller birds, and small mammals. They impale them on thorns and come back later when they're hungry. Imagine how telepathic conversations with those would unfold.

Generic Fantasy Hero: I'm not sure how to do this. I love Kassandra, but I think that she might be falling for that jerk Hardin.

Shrike: Just kill him.

Generic Fantasy Hero: What?

Shrike: You heard me, moron. Just slit his throat in his sleep. That or shove a spear through his body and leave it there for a few days. I see no problem with that.

2. Ants. An ant could rally an army better than any king or general. Ants will fight to the death for the sake of their hill. They could inspire people to rebuild after a disaster or siege, since they, you know, do it all the time.

3. Leeches/maggots. A group of leeches or maggots could be much more useful than an adorable kitty cat in case of injury. Maggots could be useful for other purposes too. Look at this situation.

The hero is a retainer for the prestigious King Phalox of Argentia, who is attending a feast at the palace of another equally powerful king. The retainer knows that the other king intends to take over Argentia and kill King Phalox, but Phalox trusts the other king wholeheartedly. As the main course, an enormous roast cow, is revealed, the hero sends his maggot friends to burrow into King Phalox's steak, and... I think it would be easy to tell what happens next. 

Can you do that with a wolf or a falcon? Heck no.