This is not too tough to get since there is nobody shooting at you. However, it does take a bit of time and patience. Your biggest threats here are eagles and long drops. The snakes are easy to spot and kill since they don't move. The eagles can be avoided by crouching and keeping close to the side of the mountain. If you know when they appear, you can just trigger them and back off to easily avoid them. When you get to the nest, watch the eagle's flight pattern and go for the feather when it's flying away from the mountain. On your way down, just take it slow and use your whip to help you down long drops, so that you don't take falling damage. If you do take damage from anything, simply walk off the edge to your death in order to restart from the latest checkpoint, rather than restarting the entire episode.