A bird is likely to "preen" when it is...

Preening is a natural behavior in birds that serves several important purposes. After a bird takes a bath, it tends to preen to restore the order of its feathers, remove any remaining water, and ensure that the feathers are aligned properly for optimal insulation and flight. This behavior helps maintain the health and functionality of their plumage, which is critical for their survival.

Additionally, when birds are content and feeling safe in their environment, they often engage in preening. It can be a comforting activity that reinforces their well-being and promotes bonding in social species. Preening in a relaxed state signifies that the bird is comfortable and can afford the time to groom, indicating overall good health and low stress levels.

Thus, both situations stated in the options lead to preening, confirming that the correct answer encapsulates the association of preening with both following a bath and being content.