Which of these birds lacks highly distinctive immature plumage during its first year?

The American Kestrel is the bird that lacks highly distinctive immature plumage during its first year. In many bird species, juvenile plumage can be quite different from adult plumage, often featuring more muted colors and varying patterns that help to distinguish them from adults.

For the American Kestrel, however, the immature individuals maintain a level of similarity to adults in their general appearance, even though their coloration might be slightly less vibrant. This lack of highly distinctive immature plumage makes it challenging to differentiate their age solely based on plumage characteristics.

In contrast, other birds listed, such as the Goshawk, Red-tailed Hawk, and Peregrine, exhibit more pronounced differences in their immature plumage. These species often have unique markings or colorations in their juvenile stages that make them distinctly identifiable from adult individuals, which is not the case with the immature American Kestrel.