True to form
To receive this quest, you need to accept Hiravias into the party. He is in Stormwall Gorge, to the right of mysterious ruins, close to the corpse of a dead animal (M28,3). After he joins you, talk to him and ask him about his animal form. You are going to need 12 Perception, 14 Power or 14 Intellect to convince Hiravias to talk to you.
You learn that his faunal form is the Autumn Staelgar which is why he is not accepted by the rest of the tribesmen. He wants to learn more about his form and for this, you need to go to the Twin Elms. There, find Tamwrn, who is close to The Golden Grove in Elms' Reach (M37,5). Let Hiravias talk to him. He tells nothing of importance, however, and advises you to go searching for more information in Blood Sands (M38), in the Northern part of Elms' Reach.
While in Blood Sands, you need to find four stone tablets. They are not hidden and they are, usually, in bigger rooms. There is no way to miss them, while exploring the location. If you have any problems finding them, take a look at the map of this location (M38). After you click on the magnifying glass, Hiravias will talk to you.
After you find all four stone tablets, Hiravias tells you that he would like to go to the Burial Isle (M56). Go to the Grotto of Echoes (M56,4). There, you find Scathden, whose faunal form is also the Autumn Staelgar, just like Hiravias's. He will strive for a fight, but Hiravias does not want it. To avoid the fight, you are going to need 12 of Resolution for the first dialogue option. For the second one, you are going to need one of the following: 14 of Power, 14 of Resolution or 14 of Dexterity.
If you do not meet these requirements, you will have to fight Scathden and 4 staelgars. What is important is that you deal with the druid in the first place. After the fight, talk to Hiravias and loot the opponent's corpse for a very good halberd.