During natural visual exploration, both head and eye movements can be used to redirect gaze to new points of interest. In order to better understand the role of head movements in this process, we recorded subjects' head orientations while they explored a set of natural images from five different categories using virtual reality head-mounted displays. While head movements are likely influenced by image content or image saliency, here we focus on their stereotyped patterns, which have a consistent relationship between the amplitude, duration, and peak velocity of movements. We find that most head movements occur along the cardinal directions, and furthermore, the head position and head velocity distributions are similar across image categories. Our results provide greater insight into the kinematics of head movements during visual exploration in virtual reality environments.