In a fighting conflict, animals may use their natural weapons such as claws, wings, musks or sharp beaks. In this type of conflict each action is represented in this way, for example, attacking is striking directly at your opponent, and manoeuvring could be flanking, or positioning yourself on high ground for example.
So, in a chase conflict against an owl, according to the rules, the owl could use its wings to gain +2 to manoeuvre in the fores , this would make it manoeuvre more easily…in the game says that you can use this weapons for OTHER conflicts, in a chase conflict the manoeuvre description would be “it’s a trip or a dirty trick” so the use of his wings would fit more with the attack for example: “head straight for your target”, as the wings would help him to go faster or even for a feint “a sudden change of direction or shortcut to get to your target”. This is just one example but many of the animal weapons would need an overhaul to apply to other types of conflicts…like also a journey for riding animals.
Another small example would be the following… in the game a fox appears that has lost its cub, the mice know where it is, the loremouse of the group succeeds in his test to communicate with the fox, so they start a negotiation conflict, the mice will tell the fox where its cub is, but the fox must move its den away from the nearby settlement and will also promise not to hunt any more mice in that area…The fox is a cunning animal, but this cannot be reflected in any way in the negotiation, the fox will simply roll 7 dice which is what its nature indicates, a moose in this situation would roll 12 dice, when the fox is supposed to be much more cunning than a moose something is wrong with this system and I can’t find a convincing solution.
I feel like I remember the rules saying somewhere that outside the mouse and the weasel families, other animals have basically no culture and very rudimentary communication ability. If I’m remembering that right, then a fox could be cunning in its actions, but would not be verbally cunning - something like, either a fox could not have a real verbal negotiation in the way you describe, or else its level 7 Nature would manifest as a non-verbal move in the conflict. Basically, sort of along the lines of, “Let the Wookie win.” Similarly with a moose, it gets to use its whole 12 nature because if the negotiation fails badly, the moose could potentially demolish several mouse settlements before anyone could do anything about it.
That, at least, is how I read/remember the rules. I could definitely be wrong.
Even if I am right, it would still be good for the game to give some more concrete ideas about how to interpret the different types of conflicts for the different types of animals (or for us to at least help each other with coming up with plausible options).
David Petersen mentioned that all the Animals are clever and reasonable in their way in Mouse Guard, if you read the comics, there is a comic called Piper the listener, in the comic the animals are intelligent, they behave according to their nature but they don´t have their own, civilised culture like weasels or mice.
The only solution I can see for this, is for each animal to receive bonuses depending on the type of conflict, and I think this is something Luke didn’t think of when he created the game, it’s normal because when you think of animals, you think of them as beasts you go to fight, but they also chase you, help you travel, you negotiate with them… so there should be a revision of the animal weapons for each conflict, or their descriptors should receive a bonus, as of today there is no rule for this. A squirrel should be faster than a crab, they both role nature to chase you, the squirrel rolls 5 dice, the crab rolls 6, I can’t make sense of this.
As for the first topic of animals’ natural weapons outside fights, I think you have latitude as a GM to include both narrative and mechanical value to those. Just be fair about letting a Loremouse test provide insights about those other applications. For non-fight confrontations, I’d say the animals have diminished special advantage, but that’s no rule.
As for the second topic, I suggest gauging whether you want a recurring NPC or a single-show cameo. If you want all the foxes of a setting to seem more cunning, you can certainly append the trait to all cameos of any fox; I don’t think that’s a problem. But, if you are planning a recurring NPC, give that fox a name, perhaps some background of confrontations with mice, and append one or more traits.
For a single cameo, learning the trait can be included in a Loremouse test outcome. For a recurring NPC maybe a Loremouse test can learn about the trait, or maybe it is simply common knowledge about that named animal.
as a caution, the NPCs cannot gain checks by playing traits against themselves, so it would only ever exist to gain a benefit. This might just feel like piling on for players that will never see that NPC embrace a detriment from having a trait or two. Still, if they get to know an animal as a recurring NPC, they can learn about the trait and look for ways to mitigate or nullify that benefit.