In this paper, we propose adaptation mechanisms for sensor networks. The existing researches on security for sensor networks have mostly concerned with confidentiality, integrity and authentication based on cryptographic mechanisms. These aspects of security are important but not enough to provide survivability of sensor networks. In this paper, we employ the software rejuvenation and reconfiguration methodology to increase the survivability of sensor nodes in sensor networks. The model uses global or local intrusion detection systems and performs 4 strategies to extend the availability of sensor nodes in sensor networks. We propose a general framework and its methodology and the security analysis and evaluation results show the feasibility of our approach.