Wikidata is a collaborative knowledge graph which has already drawn the attention of practitioners and researchers. It is the work of a community of volunteers, supported by policies, guidelines and automatic programs (bots) which perform a broad range of tasks, doing the lion's share of the work on the platform. In this paper, we highlight some of the most salient aspects of human-bot collaboration in Wikidata. We argue that the combination of automated and semi-automated work produces new challenges with respect to other online collaboration platforms.