per Craig Hendee – In the case of the Peregrine only, the males are called Tiercels. Throughout history if you said Tiercel, it meant male Peregrine. The female is called the falcon. If you said falcon, it meant and was understood to be a female Peregrine. Nowdays only the purists or those with great knowledge of the history of falconry and its language would understand it as such.
When the gentleman commented on the photo as “nice tiercel” he was saying nice male Peregrine, and meant to be understood as such. I know that he did it intentionally so that we would know of his level of knowledge. Very few falconers have a good understanding of the old terms and meanings. You technically should say male Prairie falcon, but many people would say tiercel Prairie falcon which is incorrect. There are intense epic battles over language on the internet which I love to see.
Under no circumstances should a female raptor be called a hen, such as saying hen red-tail. That will bring down the wrath of many falconers who hate it. It would be female red-tail. There are numerous other names such as a male sparrowhawk which is a musket and the female which is called the spar or sparrowhawk, or the male merlin which is called a Jack, and the male Hobby called a Robin. You just have to learn them.