A method for tracking location of passive identification tags, the method comprising: assigning, with a monitoring device, at least one passive identification tag to an active identification tag, by storing, with the monitoring device in a computer memory, associations between the active identification tag and the at least one passive identification tag, the active identification tag having a power source and an antenna; receiving, with the monitoring device, one or more signals indicative of location of the active identification tag; tracking, with the monitoring device based on received one or more signals, location of the active identification tag as the active identification tag moves in an active tracking area; and tracking, with the monitoring device, location of the at least one passive identification tags, assigned to the active identification tag, based on i) the tracked location of the active identification tag and ii) the association between the active identification tag and the assigned passive identification tag, wherein assigning a passive identification tag, of the at least one passive identification tags, to the active identification tag comprises: assigning the passive identification tag to the active identification tag in response to detecting that the active identification tag is in proximity with the passive identification tag; characterized by after assigning the passive identification tag to the active identification tag, determining, with the monitoring device, that the passive identification tag is present in a prescribed area associated with the passive identification tag, and in response to determining that the passive identification tag is present in the prescribed area, deassigning, with the monitoring device, the passive identification tag from the active identification tag. assigning, with a monitoring device, at least one passive identification tag to an active identification tag, by storing, with the monitoring device in a computer memory, associations between the active identification tag and the at least one passive identification tag, the active identification tag having a power source and an antenna; receiving, with the monitoring device, one or more signals indicative of location of the active identification tag; tracking, with the monitoring device based on received one or more signals, location of the active identification tag as the active identification tag moves in an active tracking area; and tracking, with the monitoring device, location of the at least one passive identification tags, assigned to the active identification tag, based on i) the tracked location of the active identification tag and ii) the association between the active identification tag and the assigned passive identification tag, wherein assigning a passive identification tag, of the at least one passive identification tags, to the active identification tag comprises: assigning the passive identification tag to the active identification tag in response to detecting that the active identification tag is in proximity with the passive identification tag; characterized by after assigning the passive identification tag to the active identification tag, determining, with the monitoring device, that the passive identification tag is present in a prescribed area associated with the passive identification tag, and in response to determining that the passive identification tag is present in the prescribed area, deassigning, with the monitoring device, the passive identification tag from the active identification tag. assigning the passive identification tag to the active identification tag in response to detecting that the active identification tag is in proximity with the passive identification tag; characterized by after assigning the passive identification tag to the active identification tag, determining, with the monitoring device, that the passive identification tag is present in a prescribed area associated with the passive identification tag, and in response to determining that the passive identification tag is present in the prescribed area, deassigning, with the monitoring device, the passive identification tag from the active identification tag.