Fiqh-us-Sunnah Volume 5, Hajj and ‘Umrah, Fiqh 5.061A.

If a group of people participated in killing a game intentionally, they are to pay one penalty only, because Allah says “the compensation is an offering of a domestic animal.” Ibn ‘Umar was asked about a group of people who had jointly killed a hyena while they were in the state of ihram. Ibn ‘Umar told them, “Slaughter a ram.” They asked, “Should we slaughter a ram for each person of our group?” He said, “No. Slaughter only one ram on behalf of all of you.”