What is a common behavior of the American Kestrel when it is excited or agitated?

The behavior of tail pumping in the American Kestrel is a well-documented response when the bird is excited or agitated. This action involves the bird moving its tail up and down rapidly, creating a visible display. This behavior can signal various emotional states, such as agitation, excitement, or even an attempt to attract a mate.

Tail pumping is particularly notable in Kestrels because it is a distinctive visual cue and might be accompanied by vocalizations or other physical postures that indicate heightened emotional states. Such behaviors allow the bird to communicate its condition or intentions to other birds in the vicinity.

In contrast, purring is typically a sign of contentment, circling can be related to hunting or positioning rather than agitation, and a hunched posture usually indicates a defensive behavior rather than excitement. Thus, tail pumping is clearly linked to states of excitement or agitation in the American Kestrel, making it the correct and most appropriate choice in this context.