He’s simply an enterprising trapper who would prefer it if you just killed and skinned the animals and sold the pelts and parts to him for special garments and trinkets. Gus is not a quest-giver, and working for him won’t give you any Naturalist XP. There’s a reason for that! When you meet Davenport you’ll also be introduced to Gus MacMillan, the less animal-friendly secondary vendor introduced in this update. Harriet will provide the player with a field guide for cataloguing all of the animals in Red Dead Online, but you can’t complete each entry without killing and skinning every animal. This will also allow you to buy Sedative Ammo from Harriet, which enables you to tranquilise and sample animals, starting your career as a Naturalist.
You can find Davenport at the Welcome Center in Strawberry once you’ve updated the game, where you can pay 25 Gold Bars to access the Naturalist Sample Kit.