Earl was a DHARMA Initiative ornithologist, who was a new recruit in 1973. He may have been killed along with other members of the DHARMA Initiative in the Purge, or he may have been evacuated off the island sometime between 1977 and The Purge.
On the Island
Earl appeared in the Barracks video
After arrived on the island, Earl was welcomed by Casey, June and Mike, then he went to the Processing Center along with the other new recruits. Inside the center, Earl was standing in front of the television, and watching the Barracks video next to Robert. ("The Man Behind the Curtain")