A B S T R A C TTemperature and head movement are relevant parameters when analyzing the farrowing behavior of sows. Obtaining these body parameters in a way that is nonintrusive to animals is a major challenge in the harsh farrowing pen environment. Due to the presence of large amounts of metal as well as the unpredictable behavior of animals, such environments are not ideal for wired communication platforms. Intrusive measuring equipment may cause animals to deviate from their normal behavioral patterns invalidating gathered sensor data. Using lightweight, highly mobile and wireless sensor equipment is thus essential for unobtrusive measurements. This article discusses the challenges involved in developing a lightweight and flexible wireless sensor network infrastructure platform used in the analysis of sow behavior during farrowing. The platform is based on the customizable wireless sensor platform Shimmer and the open source software frameworks TinyOS and SPINE. Embedded in hot melt adhesive, the Shimmer modules were used as ear tags providing biologists with head movement and temperature data throughout six months. Focus is on the technical aspects of developing a system faced with mutually exclusive and changing requirements in an iterative and progressive research project, drawing upon the experiences from several stages of live experiments with farrowing sows.