Owls aren't the only birds that make pellets.  Almost any bird that eats animals with bones or exoskeletons will make a pellet after their meal.  Before dissecting this pellet, guess what you think this gull ate?  Will you find fish bones, shells, insect parts, rodent bones, or reptile bones? Go ahead and take a guess - we'll see how well you did after you finish dissecting this pellet.