The necessity for having an efficient medium access control (MAC) protocol is highly obvious with the emergence of wireless sensor networks (WSNs). The MAC protocol has increasingly been significant in advancing the performance of WSNs. In this paper, a low duty cycle, energy-efficient and mobility-based Boarder Node Medium Access Control (BN-MAC) hybrid protocol is introduced for WSNs that controls overhearing, idle listening and congestion issues by preserving energy over the WSNs. Further, the BN-MAC hybrid protocol handles the scalability and mobility of nodes using the pheromone termite (PT) analytical model. BN-MAC leverages the features of contention and schedule-based MAC protocols. The contention encompasses the novel semi-synchronous approach that helps obtain faster access to the medium. The schedule-based part helps reduce the collision and overhearing problems. \n The idle listening control (ILC) model is embedded within the BN-MAC that administers the nodes to go to sleep after performing their tasks to saves additional energy. The least distance smart neighboring search (LDSNS) model is used to determine the shortest and most efficient path in a one-hop neighborhood. \nEvaluation of the BN-MAC is conducted using network simulator-2 (ns2), then compared its quality of service (QoS) parameters with other known hybrid MAC protocols including X-MAC, Zebra medium access control (Z-MAC), mobility-aware SMAC (MS-MAC), advertisement-based MAC (A-MAC), Adaptive Duty Cycle SMAC (ADC-SMAC) and Mobile Sensor (MobiSense) MAC protocols.