More and more users or applications showed high interest in obtaining moving object locations from a wireless sensor network. However, a moving object usually updates its location very frequently, and thus, a great number of messages for updating the locations in the wireless sensor networks are incurred. In this paper, we propose an index structure, called the Gossip-enabled Spatial Index Tree (GSI-tree), to support efficient communication for location updates. Our idea is to utilize the gossip property of the sensor communication to let the neighboring paths of the GSI-tree share the transmitted message. In this way, the nodes managing a past location can deregister the object location independently by hearing the registration messages from the neighboring nodes.