The official state bird of Delaware is the Blue Hen chicken. This bird was named the state bird of Delaware in 1939, but the bird itself is not actually a separate species. Instead, this bird is named as such because of the blue color of its feathers. Delaware has a variety of these Blue Hen chickens, and they were adopted as the state bird because of their visibility.
The idea of the Blue Hen chicken as the state bird of Delaware dates back to the time of the American Revolutionary War. At that time, a group of soldiers from Delaware gathered a reputation for having a tremendous amount of courage, and they were called the Blue Hen's Chickens, thus the name. After that, the nickname stuck with the group, and it became a term of endearment to be called the son of the "Blue Hens." The Blue Hen became used throughout publications in the region, and became a popular symbol during the Civil War as well.
Of note, the Blue Hen chicken was also bred because it was a good fighter, thus the tie to the fighting men who served in the Revolution. While the Blue Hen chicken was popular for use in cockfights during the time of the revolution, that is now illegal, as it is considered to be cruel to animals. The Blue Hen chicken is no longer used for cockfights, or any other bird for that matter.
The Blue Hen chicken is so popular throughout the state of Delaware that it was adopted by the local university as well. The sports teams for the University of Delaware are called the Blue Hens, and the university even maintains a flock of Blue Hen chickens that can be seen around campus from time to time. The group of chickens was donated by a local organization in the 1960s, and the flock is maintained by the local state veterinary college. The name of the Blue Hen chicken mascot is called YoUDee, which is the colloquial name given to the school, U.D., which stands for the University of Delaware.
In addition, the Blue Hen chicken is the mascot of the local airlift squadron in Delaware. The 166th airlift wing and the 142nd airlift squadron are both stationed in Delaware, and they use the bird as their mascot.
The Blue Hen chicken has been cross-bred with another bird, the Blue Andalusian breed, which is from Spain. As a result, the character traits of the Blue Hen chicken have changed significantly during the past few years. Now, the Blue Hen chicken looks a bit more like the bird from the Mediterranean area and does not look as much like a chicken anymore. Regardless, the Blue Hen chicken is still the state bird, and it still holds an important place in the lore of local citizens.