(CNN) -- The U.S. Coast Guard and several California state agencies are investigating how five Brown Pelicans turned up partially covered in oil near Santa Barbara this week.
A seabird rehabilitation volunteer rescued the first two birds near Elwood Beach on Tuesday, the Coast Guard said in a statement.
Three other birds were spotted near East Beach on Wednesday, but only one was rescued.
A Coast Guard helicopter flew over the area just before dark Wednesday, and could not locate a spill or sheen. Another search is planned for Thursday.
Meanwhile, pollution investigators from Marine Safety Detachment Santa Barbara could not find a spill during searches of beaches where the pelicans were located.
Area offshore oil platforms have been contacted with all rigs reporting normal oil operations and levels, the Coast Guard said.
A rehabilitation specialist says the three pelicans will be transported Thursday to San Pedro, California, where a seabird specialist will clean them.
Responders from California's Department of Fish and Game are en route, and the California Emergency Operations Service and Emergency Management Agency have been notified, according to the Coast Guard.