As part of Jurassic Park’s security measures, a very large number of motion-sensitive security cameras were placed throughout Isla Nublar in order to keep track of the park’s 238 dinosaurs. However, these cameras covered only 92% of Jurassic Park; the remaining 8% experienced too much interference from environmental motion to be used effectively, namely around the jungle river. In this way, an animal could theoretically travel across the island undetected simply by staying near the river where the cameras would not register their movements.
This security system was one of the reasons that the animals were able to continue breeding without being detected. In addition, animals such as the Othnielia, and the Microceratops were able to elude detection by the motion trackers by utilizing the treetops with which to travel. The reason that there was such a large undetected increase in Velociraptors was because they were hiding in the Waterworks, which had no motion trackers due to being outside of the paddock areas, and was considered a maintenance area. These oversights by the park staff proved to be compounding, as almost sixty additional animals were able to hide due to the disparity in the motion sensors.