The invention relates to a fringe capacitance sensor (10) for sensing objects, particularly, but not exclusively, pests, a sensor unit (100) comprising one or more fringe capacitance sensors, a system comprising a plurality of sensor units in a mesh topology or other wireless network and a method for intelligently detecting object activity, such as the presence of a pest, for example, a rodent or crawling, burrowing or flying insect. It can also be applied to the management of animals, whether in the wild or on farms. A preferred sensor (10) for detecting changes (Δ) in fringe capacitance (A) comprises an electrically conductive sensor conductor (12) and two electrically conductive un-grounded conductors (14a; 14b) disposed one on either side (16a; 16b) of the sensor conductor (12) to form a triplet (14a-12-14b). The conductors (12, 14a, 14b) are supported on an un-grounded conductive substrate (18) which is electrically isolated (20) from said conductors (12, 14a, 14b) and each conductor (14a,12;14b) is of a width (w), and thickness (t), and is spaced by a distance (d) from another such that the sensor is tuned to detect or identify a given animal.