A monitoring system that is configured to monitor a property is disclosed. The monitoring system includes a passive infrared (PIR) sensor configured to generate reference PIR data that represents motion within an area of the property; an auxiliary sensor configured to generate auxiliary sensor data that represents an attribute of the area of the property; and a motion sensor device. The motion sensor device is configured to: obtain the reference PIR data; determine that a first set of motion detection criteria is satisfied by the reference PIR data; in response to determining that the first set of motion detection criteria is satisfied by the reference PIR data, obtain the auxiliary sensor data; obtain a second set of motion detection criteria based on the reference PIR data and the auxiliary sensor data; and determine whether the second set of motion detection criteria is satisfied by additional PIR data.