This guide will let you know where to find the squirrels In Horizon Forbidden West; Go through the guide, and follow the simple instructions.
To find squirrels, you will need to go to the campfire southeast of the quarry and press and hold the R3 button. You will see a source of the spirit energy of the animals so that you can track them from there. Walk around the area and find the squirrel; you also have to kill raccoons and balls to get ingredients.
After hunting the squirrels and killing them, you have to kill more than two and then head back to the campfire. Then go back to the town from the campfire.
From the main town, head back to the campfire and go back to the area, and you will find two more squirrels again, so you have to kill them and do the same process a few more times, and you will be able to get all the squirrels you require as shown in the image below.