1. An unmanned aerial vehicle (UAV) comprising: an article support configured to carry an article to a delivery destination; one or more sensors configured to detect an interactive object; a loudspeaker configured to produce audio output; one or more processors; one or more non-transitory computer-readable media storing computer-executable instructions that, when executed on the one or more processors, cause the UAV to perform actions comprising: detecting the interactive object at the delivery destination using the one or more sensors; determining whether the interactive object is within an unsafe distance of an article drop site at the delivery destination based on the detection; when it is determined that the interactive object is within an unsafe distance from the article drop site, producing a first output speech using the loudspeaker, wherein the first output speech requests that the interactive object move away from the article drop site; when it is determined that the interactive object is outside the unsafe distance from the article drop site, descending to the article drop site to deliver the article.