Some people, such as vets, may be a bit more familiar than visitors, but not as familiar as keepers. A keeper undertaking routine husbandry procedures might inadvertently send direct signals to the animal, to which the animal will then respond. Nature, frequency and type of these human–zoo‐animal interactions all provide fruitful opportunities for learning. Zoo keepers provide learning opportunities through permanent or temporary enclosure design and changes. Human–animal bonds have been reported to occur, by a number of zoo keepers; it is difficult to determine what if any emotional experience animals feel. The ability of agricultural animals to discriminate between different categories of people has been attributed to them learning to recognise the differences in peoples' behaviour and clothing. Zoos of course maintain many different species and so better understanding whether other taxa and species are able to discriminate between familiar and unfamiliar people is crucial.