Birth of the Conservation Movement

 is a side-mission in the Red Dead Redemption Undead Nightmare DLC pack.

Story
Marston will come across a frightened frontiersman shooting randomly into the wilderness and yelling about Sasquatches. He will then task the player with killing Sasquatch in the Tall Trees area.

Mission Prerequisites
Before this mission becomes available, the player must complete:
 * "Curious Tales from Blackwater, USA"

Mission Objectives
To complete this mission the player must:
 * Speak with the Sasquatch Hunter in Tanner's Reach.
 * Hunt 6 Sasquatches in Tall Trees.
 * Speak to the last Sasquatch.

Mission Details
After beginning the mission, a Sasquatch's general location will be marked with a light-green circle on the world map. After the player has killed 5 Sasquatches, he will come across the last one, who will tell John a very sad story about how he is the last of his kind. Facing only loneliness, the Sasquatch pleads with Marston to end his life. After this the mission ends and the player having the choice of either killing the Sasquatch or leaving it be.

Trivia

 * Despite the hunter stating that the Sasquatch are dangerous, the creatures will not attack the player or anything else.
 * It is unknown why no infected Sasquatch are present ingame. It could be that they are immune to the virus, meaning that humanity may have been able to synthesize a cure from them.
 * In the opening cutscene, Ayauhteotl is found standing next to the frontiersman.
 * In the final cutscene, the Sasquatch says "Shoot me. I can't take it anymore. Make it stop!". However, if the player attempts to kill the Sasquatch, it will run away. It contradicts what it was saying in the cutscene. Whether this is accidental is unknown.