These will sighting refresh regularly, but the pool of animals available is fairly small.

As you level the role you will unlock a total of three active Legendary Animal Sightings you can choose from. Instead of taking the sample you will instead be killing and skinning the Legendary Animal to give its materials to Gus. During these missions you are tasked with finding and taking a sample from a certain Legendary Animal. The first way is a guaranteed but select pool that comes from the Legendary Animal Sightings Harriet gives you starting at Naturalist Level 5. There are a few ways to get Legendary Animals in Red Dead Online.