Created by Free Flinker, take these as guidelines:
STR and CON should be mostly size dependant
AGI and DEX should depend upon the type of critter and it's habits
INT, WIS and CHA either need to be void or a special category "animal" if things like cunning, perception and morale are going to be tied to these stats. Don't want it to be too complex though.
If it's a carnivore I'd suggest expert attack with whatever means they have available.
Also, some sort of movement ability for all animals and where applicable tracking (via scent), hiding (camouflage) and sneaking (for relevant predators) at expert. I think only magical animals should get master in such skills.
And specifically with the examples asked for:
Armour: good - a layer of fat and muscle blunt the impact of many a blow
bite (a) - not the bear's primary mode of attack but their bite is extremely painful nevertheless
claw (e) - 4inch claws capable of slashing leather armour
hug (e) - a grappling attack capable of overbearing an opponent, pinning them and mauling them at the same time using the bear's considerable weight
tracking (a) - bears can scent quite well
running (e) - a bear can run faster than a human over open ground
climbing (e) - good at climbing trees and steep ground the bear can climb most things that will hold their weight
swimming (e) - excellent swimmers
Spider (6" to 1' leg span)
CON: average but capable of regenerating damage and even lost limbs given enough time
Armour: weak - chitinous body that is nevertheless quite weak compared to a well made or heavy weapon
bite (e) - primary attack mode capable of delivering venom that causes bluring of vision, lethargy, nausea and in some cases death from anaphalactic shock
jumping (e) - some species are capable of jumping up to 10x their body length
running (e) - spider are much faster than a human over short distances, capable of sprinting at a high velocity
climbing (m) - spiders are capable of adhering to almost any surface no matter the angle/incline
hiding (e) - used by species that spin webs and wait for their prey. They are adept at laying in wait, out of sight. This skill is also used to determine success at spotting catch webs too.
Beetle (large, 1' length)
Armour: good - a thick and smooth chitinous carapace protects the beetle from all but the strongest blows
pincer bite (e) - primary attack mode capable of inflicting extremely painful injuries that can pierce leather and even be felt through chain
running (e) - able to outrun a human over short distances
swimming (a) - some species are more capable than others but all can negotiate their way through the water with some skill
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