A method of performing an animal related action on an animal by means of a robot arm is disclosed. The method includes carrying out measurements on the animal by means of a sensor for locating at least one animal part, generating, on the basis of the measurements, a list of data each corresponding to a possible animal part, comparing the data on the list with historical data regarding at least one animal part, assigning to each of the data on the list, on the basis of the comparison, a probability value for actual correspondence with at least one animal part, selecting as target position that possible target position that corresponds to the data on the list having the highest probability value and moving the robot arm to the target position which corresponds to the animal part found and performing there the animal related action.