Zoologist Trophy in Red Dead Redemption 2
Study every animal across all states in Story Mode.
How to unlock ZoologistIn your inventory is a pair of binoculars and equipping them will allow you to study animals (as long as they're mostly visible) by holding down . You can actually study many animals if you're close enough to them when you're aiming at them; the binoculars just make it easier. You can check your progress on this via Progress => Compendium => Animals. If the picture of the animal has a full white bar under it, you've done everything you can with that animal – i.e. studied it, tracked it, killed it and skinned it. If there's not a full white bar, select the pictured animal and see if "studied" says "yes" under it. Although you will ultimately want to have a full white bar under the animal, due to Skin Deep.
NOTE: Any animal that is unique to Guarma Island, visited in Chapter 5, doesn't count towards this trophy – this includes the Carolina Parakeet, the Blue and Yellow Macaw, the Green Macaw, the Scarlet Macaw, the Red-footed Booby, the Red Boa, the Rainbow Boa, the Sunglow Boa and the Fer-de-Lance Rattlesnake. Also not required are Rufus the dog (found in the Epilogue) and all Legendary animals.
[Credit to themindisacity]