Finally, a plethora of fine wild critters for Keitha's animal companion selection!
The animal companion is an animal which the ranger has raised since its infancy, and hence is difficult to replace. But in that animal the ranger finds a loyal servant who shares a special bond with her, and with whom the ranger can communicate more easily than she can with any other animal. (But still, a few ranks in the Animal Empathy skill couldn't hurt, especially if Keitha has any aspiration of drowning entire villages beneath a tide of ravenous beasts....
)
Keep in mind that a creature's size has a bearing on its effective Armor Class, as well as certain conditional outcomes of actions such as hiding, sneaking or fitting through narrow passages or apertures. Larger creatures tend to be physically formidalble yet easier to hit and easier to detect; the inverse is true of smaller creatures.
Also to be considered when choosing an animal companion and its role to Keitha is the animal's innocuity; people are more likely to react with fear or hostility to a menacing animal than they are to react negatively to a harmless one. Peasants might react to the sight of a wolf or a marsh viper roaming through their village by reaching for their pitchforks, while a toad, a crow or a small dog will probably be shooed away harmlessly or otherwise ignored.
Certain animals may even be welcomed or receive positive reactions under certain conditions; creatures like ravens, owls and monkeys may be seen as good omens in certain superstitious cultures, for example. However, superstition can be a two-edged sword; housecats were lauded and protected as messengers from the gods in ancient Egypt but were hunted and killed as servants of the Devil in numerous medieval European cultures.
(Note that I've omitted a number of animals listed in the Monster Manual who wouldn't qualify, either because they have too many Hit Dice to be animal companions (ie. brown bears and horses), they're native to remote or exotic locations (ie. cheetahs) or they're incapable of surviving on land (ie. squids).)
BadgerSize: Tiny
Hit Dice: 1d8 +2 (10 HP)
Speed: 30', burrowing 10'
AC: 15 (+2 size, +3 Dex)
Attacks: 2 claws (1d2-1 Damage), 1 bite (1d3-1 Dam)
Abilities: Str , Dex , Con , Int , Wis , Cha
Skills: Escape Artist +7, Listen +4, Spot +4
Special: Weapon Finesse Feats (claw and bite), Rage (similar to Barbarian Rage; +4 Str, +4 Con and -2 AC when wounded), Scent (keen sense of smell can substitute for vision when making Spot checks)
BatSize: Diminutive
Hit Dice: 1/4 d8 (2 HP)
Speed: 5', 40' flying (Good maneuverability)
AC: 16 (+4 size, +2 Dex)
Attacks: --
Abilities: Str 1, Dex 15, Con 10, Int 2, Wis 14, Cha 4
Skills: Listen +9, Move Silently +6, Spot +9
Special: Blindsight (the ability to see even in perfect darkness); +4 bonus to Spot and Listen checks if Blindsight is active. A bat's Blindsight is, of course, echolocation, and hence can be negated by effects such as a Silence spell.
Black Bear, YoungSize: Medium
Hit Dice: 2d8 +4 (18 HP)
Speed: 40'
AC: 13 (+1 Dex, +2 natural)
Attacks: 2 claws (1d4+2 Dam), bite (1d6+1)
Abilities: Str 17, Dex 13, Con 15, Int 2, Wis 12, Cha 6
Skills: Climb +6, Listen +4, Spot +7, Swim +8
Special: Scent
Boar, YoungSize: Medium
Hit Dice: 2d8+7 (21 HP)
Speed: 40'
AC: 16 (+6 natural)
Attacks: Gore (1d8+2 Dam)
Abilities: Str 14, Dex 10, Con 16, Int 2, Wis 12, Cha 4
Skills: Listen +7, Spot +5
Special: Scent, Ferocity (can continue to fight without penalty even while disabled or dying)
Cat (common housecat)
Size: Tiny
Hit Dice: 1/2 d8 (4 HP)
Speed: 30'
AC: 14 (+2 size, +2 Dex)
Attacks: 2 claws (1d2-4), bite (1d3-4)
Abilities: Str 3, Dex 15, Con 10, Int 2, Wis 12, Cha 7
Skills: Balance +10, Climb +5, Hide +7 (+8 in tall grass or similar), Listen +4, Move Silently +9, Spot +4
Special: Weapon Finesse (claw and bite), +4 racial bonus to all Hide and Move Silently checks, +8 racial bonus to all Balance checks
Crocodile, YoungSize: Medium
Hit Dice: 2d8+8 (22 HP)
Speed: 20', swimming 30'
AC: 15 (+1 Dex, +4 natural)
Attacks: Bite (1d8+4 Dam) or tail slap (1d12+4 Dam)
Abilities: Str 17, Dex 12, Con 16, Int 2, Wis 12, Cha 2
Skills: Hide +7, Listen +5, Spot +5
Special: Improved Grab (if it hits a Medium-sized or smaller creature with its bite, it may drag the creature into deeper water; in addition to drowning (if applicable), the prey takes automatic bite damage each round until it either dies or breaks the hold), +12 racial bonus to Hide checks while submerged
Dog(includes small dogs, terriers and similarly sized canines, such as coyotes)
Size: Small
Hit Dice: 1d8 +2 (10 HP)
Speed: 40'
AC: 15 (+1 size, +3 Dex, +1 natural)
Attacks: Bite (1d4+1 Dam)
Abilities: Str 13, Dex 17, Con 15, Int 2, Wis 12, Cha 6
Skills: Listen +5, Spot +5, Swim +5, Wilderness Lore +1
Special: Scent
Dog, Riding(includes larger working dogs, such as St. Bernards, Collies and Rottweilers; so named because humanoids like halflings often train such dogs for use as mounts)
Size: Medium
Hit Dice: 2d8+4 (18 HP)
Speed: 40'
AC: 16 (+2 Dex, +4 natural)
Attacks: Bite (1d6+3 Dam)
Abilities: Str 15, Dex 15, Con 15, Int 2, Wis 12, Cha 6
Skills: Listen +5, Spot +5, Swim +5, Wilderness Lore +1
Special: Scent
DonkeySize: Medium
Hit Dice: 2d8+2 (16 HP)
Speed: 30'
AC: 13 (+1 Dex, +2 natural)
Attacks: Bite (1d2 Dam) or hoof (1d4 Dam)
Abilities: Str 10, Dex 13, Con 12, Int 1, Wis 11, Cha 4
Skills: Balance +3, Listen +5, Spot +5
Special: Scent
EagleSize: Small
Hit Dice: 1d8+1 (9 HP)
Speed: 10', flying 80' (Average)
AC: 14 (+1 size, +2 Dex, +1 natural)
Attacks: 2 claws (1d3 Dam), bite (1d4 Dam)
Abilities: Str 10, Dex 15, Con 12, Int 2, Wis 14, Cha 6
Skills: Listen +6, Spot +6
Special: +8 racial bonus to Spot checks in daylight
HawkSize: Tiny
Hit Dice: 1d8 (8 HP)
Speed: 10', flying 60' (Average)
AC: 17 (+2 size, +3 Dex, +2 natural)
Attacks: Claws (1d4-2)
Abilities: Str 6, Dex 17, Con 10, Int 2, Wis 14, Cha 6
Skills: Listen +6, Spot +6
Special: Weapon Finesse (claws), +8 racial bonus to Spot checks in daylight
Lizard(describes small, nonvenomous lizards of perhaps 1-2 feet in length, such as an iguana)
Size: Tiny
Hit Dice: 1/2 d8 (4 HP)
Speed: 20', climbing 20'
AC: 14 (+2 size, +2 Dex)
Attacks: Bite (1d4)
Abilities: Str 3, Dex 15, Con 10, Int 2, Wis 12, Cha 2
Skills: Balance +10, Climb +12, Hide +13, Listen +4, Spot +4
Special: Weapon Finesse (bite)
MonkeySize: Tiny
Hit Dice: 1d8 (8 HP)
Speed: 30', climbing 30'
AC: 14 (+2 size, +2 Dex)
Attacks: Bite (1d3-4 Dam)
Abilities: Str 3, Dex 15, Con 10, Int 2, Wis 12, Cha 5
Skills: Balance +10, Climb +13, Hide +13, Listen +4, Spot +4
Special: Weapon Finesse (bite), Dex modifier used for Climb checks, +8 racial modifier for Balance checks
OwlSize: Tiny
Hit Dice: 1d8 (8 HP)
Speed: 10', flying 40' (Average)
AC: 17 (+2 size, +3 Dex, +2 natural)
Attacks: Claws (1d2-2 Dam)
Abilities: Str 6, Dex 17, Con 10, Int 2, Wis 14, Cha 4
Skills: Listen +14, Move Silently +20, Spot +6
Special: Weapon Finesse (claws), Lowlight Vision, +8 racial bonus to Listen checks, +14 racial bonus to Move Silently while flying, +8 racial bonus to Spot checks in dusk and darkness
PonySize: Medium
Hit Dice: 2d8+2 (16 HP)
Speed: 40'
AC: 13 (+1 Dex, +2 natural)
Attacks: 2 hooves (1d3+1 Dam)
Abilities: Str 13, Dex 13, Con 12, Int 2, Wis 11, Cha 4
Skills: Listen +5, Spot +5
Special: Scent
RatSize: Tiny
Hit Dice: 1/4 d8 (2 HP)
Speed: 15', climbing 15'
AC: 14 (size +2, Dex +2)
Attacks: Bite (1d3-4)
Abilities: Str 2, Dex 15, Con 10, Int 2, Wis 12, Cha 2
Skills: Balance +10, Climb +12, Hide +18, Move Silently +10
Special: Scent, Weapon Finesse (bite), +4 racial bonus to Hide and Move Silently checks, +8 racial bonus to Balance checks, Dex modifier used for Climb checks
Raven(applies to similar nonpredatory birds, such as crows)
Size: Tiny
Hit Dice: 1/4 d8 (2 HP)
Speed: 10', flying 40' (Average)
AC: 14 (+2 size, +2 Dex)
Attacks: Claws (1d2-5 Dam)
Abilities: Str 1, Dex 15, Con 10, Int 2, Wis 14, Cha 6
Skills: Listen +6, Spot +6
Special: Weapon Finesse (claws)
Snake, Young ConstrictorSize: Medium
Hit Dice: 2d8+3 (17 HP)
Speed: 20', climbing 20', swimming 20'
AC: 15 (+3 Dex, +2 natural)
Attacks: Bite (1d3+4)
Abilities: Str 16, Dex 16, Con 12, Int 1, Wis 12, Cha 2
Skills: Balance +11, Climb +14, Hide +11, Listen +9, Spot +9
Special: Scent, Improved Grab (may Constrict if its bite attack hits), Constrict (the round following a successful bite, may continuously deal 1d3+3 damage to a Medium or smaller creature until either the hold is broken or the creature dies)
Snake, Tiny ViperSize: Tiny
Hit Dice: 1/4 d8 (2 HP)
Speed: 15', climb 15', swim 15'
AC: 17 (+2 size, +3 Dex, +2 natural)
Attacks: Bite (no Damage)
Abilities: Str 6, Dex 17, Con 11, Int 1, Wis 12, Cha 2
Skills: Balance +11, Climb +12, Hide +18, Listen +8, Spot +8
Special: Scent, Weapon Finesse (bite),
Poison (on successful bite, victim must pass Fortitude save at DC 11 or be poisoned (1d6 Constitution damage initial, 1d6 Con damage secondary))
Snake, Small ViperSize: Small
Hit Dice: 1d8 (8 HP)
Speed: 20', climb 20', swim 20'
AC: 17 (+1 size, +3 Dex, +3 natural)
Attacks: Bite (1d2-2 Dam)
Abilities: Str 6, Dex 17, Con 11, Int 1, Wis 12, Cha 2
Skills: Balance +11, Climb +12, Hide +15, Listen +9, Spot +9
Special: Scent, Weapon Finesse (bite),
Poison (on successful bite, victim must pass Fortitude save at DC 11 or be poisoned (1d6 Constitution damage initial, 1d6 Con damage secondary))
Snake, Medium ViperSize: Medium
Hit Dice: 2d8 (14 HP)
Speed: 20', 20' climb, 20' swim
AC: 16 (+3 Dex, +3 natural)
Attacks: Bite (1d4-1 Dam)
Abilities: Str 8, Dex 17, Con 11, Int 1, Wis 12, Cha 2
Skills: Balance +11, Climb +11, Hide +12, Listen +9, Spot +9
Special: Scent, Weapon Finesse (bite),
Poison (on successful bite, victim must pass Fortitude save at DC 11 or be poisoned (1d6 Constitution damage initial, 1d6 Con damage secondary))
ToadSize: Diminutive
Hit Dice: 1/4 d8 (2 HP)
Speed: 5'
AC: 15 (+4 size, +1 Dex)
Attacks: --
Abilities: Str 1, Dex 12, Con 11, Int 1, Wis 14, Cha 4
Skills: Hide +21, Listen +5, Spot +5
Special: +4 racial bonus to Hide checks due to skin coloration
WeaselSize: Tiny
Hit Dice: 1/2 d8 (4 HP)
Speed: 20', climb 20'
AC: 14 (+2 size, +2 Dex)
Attacks: Bite (1d3-4 Dam)
Abilities: Str 3, Dex 15, Con 10, Int 2, Wis 12, Cha 5
Skills: Balance +10, Climb +11, Hide +13, Move Silently +9, Spot +4
Special: Weapon Finesse (bite), Scent, Attach (if its bite hits, the weasel's jaws latch on and do continuous damage; an attached weasel has AC 12), +4 racial bonus to Move Silently, +8 racial bonus to Balance, Dex modifier used for Climb checks
WolfSize: Medium
Hit Dice: 2d8+4 (18 HP)
Speed: 50'
AC: 14 (+2 Dex, +2 natural)
Attacks: Bite (1d6+1 Dam)
Abilities: Str 13, Dex 15, Con 15, Int 2, Wis 12, Cha 6
Skills: Hide +3, Listen +6, Move Silently +4, Spot +4, Wilderness Lore +1
Special: Scent, Trip (a wolf that hits with a bite may attempt to trip the victim as a free action automatically and without provoking an Attack of Opportunity; if the attempt fails, the victim cannot react to trip the wolf), +4 racial bonus to Wilderness Lore when tracking by scent
Wolverine, YoungSize: Medium
Hit Dice: 2d8+8 (22 HP)
Speed: 30', climb 10', burrow 10'
AC: 14 (+2 Dex, +2 natural)
Attacks: 2 claws (1d4+1), 1 bite (1d6+1)
Abilities: Str 13, Dex 14, Con 19, Int 1, Wis 12, Cha 10
Skills: Climb 15, Listen +6, Spot +6
Special: Scent, Rage (similar to a badger's Rage, but worse; a wounded wolverine cannot end its berserk fury voluntarily)
Speak with me if you wish to have any animal not listed above (a rabbit, for example) or if you wish to modify one of the animal templates above (ie. a medium viper who happens to be a king cobra would sacrifice some of its Hide in exchange for Intimidate and a minor increase in Charisma, which is the whole purpose of the cobra's hissing and hood-flaring when threatened or hostile; a rattlesnake would do a similar exchange with Move Silently and Intimidate).