In one embodiment, a method includes receiving, by a tracking server from a first computing device, a request to establish a search party to locate a tracking device associated with the tracking server. The method includes, until a threshold number of computing devices have been added to the search party: identifying one or more candidate second computing devices for addition to the search party, each candidate second computing device satisfying criteria for inclusion in the search party; adding one or more of the candidate second computing devices to the search party in response to receiving an acceptance of a request sent to the candidate second computing devices to join the search party; determining that a number of second computing devices added to the search party fails to satisfy the threshold number of computing devices; and modifying the criteria for inclusion in the search party.