Wireless sensors networks (WSNs) have been widely deployed for habitat monitoring, structure monitoring, fire detection and object tracking applications. Although WSNs can provide continuous sensor readings, the battery, computation and communication resources are limited in wireless sensors. Recently, mobile phones have been suggested to be utilized as sensors in various participatory sensing campaigns. However, it is hard to guarantee the sensing quality due to the mobility and sensing quality of individual mobile participants. In this paper, we consider a collaborative sensing paradigm which utilizes both mobile phones and stationary sensors to perform sensing. It enables mobile phones and stationary sensors to complement each other in order to achieve better overall sensing quality and reduce the energy consumption of wireless sensors. We propose an adaptive collaborative sensing algorithm that can coordinate sensing among the available mobile users and the stationary sensors in the area of interest. Mobile phones are given higher priority to perform sensing, while stationary sensors will be enabled if the required sensing quality is not reached. Our algorithm is adaptive to the mobility and sensing quality of the mobile phones, as well as the unusual events in the environment. Simulations are conducted to evaluate the sensing quality, the number of mobile phones and stationary sensors enabled with our algorithm.