Forest officials at Sanjay Gandhi National Park (SGNP), Borivali, conducted a manual census for 2013 Saturday. As many as 20 machaans (watch towers) were allocated to two forest officials each. Spread over 103 sq km, SGNP is home to animals such as spotted deer, sambhar, leopards, flying fox and langur, apart from a variety of reptiles and birds. A total of 40 people, including citizens, were part of the annual exercise. Prashant Ghadge (40), an officer on census duty, said a machaan, covered with leaves and branches, is built near an artificial water body at a height of around 20 ft. "We wait overnight and record the number of animals we spot," he said. Pug marks are recorded and sent to Wildlife Institute of India, Dehradun. "The institute matches each pug mark to check for duplication of samples," said S D Saste, assistant conservator of forest (ACF), adding that only samples of carnivores are sent for matching. "There is a large number of herbivores in the forest, so it is tough to determine an exact figure," he said. The manual method is, however, prone to errors and deemed a general "wildlife monitoring" drill, Saste said. "Manual census is a traditional method. The department follows it for monitoring and control purposes to record the variety of species present in the forest. We, however, do not call it the actual census," he said. The actual census, conducted in June last year, comprised cameras mounted at strategic locations and transit points. "The cameras were placed near water bodies frequented by leopards. Later, a count of 21 leopards was confirmed," Saste said. The camera method was adopted around four-five years ago and continues to be the official method of census at the national park. Saste added, "In summers particularly, when forest fires are common, we allocate a forest protection squad for night patrols. There are four control rooms and whenever a fire is detected, an alert is sent to all the rooms," he said, adding that there were fewer forest fires this year.