Managing wireless sensor networks in an energy-efficient manner is no mean feat. Management requests and responses create additional traffic in addition to the data issuing from the network's actual sensing application. Effective management therefore requires balancing the need for detailed oversight of the network against the energy consumption of the management system itself. This paper explores whether sending the management data and the sensing data together rather than separately can reduce the management system's energy footprint. From the results of our experiment using BMAC and DYMO on MICAz motes running on TinyOS, we find that our approach does indeed substantially reduce the communication costs of the management system. We discuss different models for coop- eration between the management system and the sensing application and estimate the potential trade-off between the number of packet transmissions and the delay of management data. To put the theoretical results into practice, we present a management framework for monitoring wireless sensor networks that is independent of the actual sensing application. This framework allows fine-grained control over the latency tolerated for management requests for the sake of reduced energy consumption. Measurements based on a prototype implementation of the framework in an experimental setup show that up to 61% of the energy previously needed for management requests can be saved.