The English language has protocols and rules for when to capitalize and when not to. City names and our own names for instance are always supposed to be capitalized. Often scientific creature names have capitals and common names do not.
A capital letter is an honor bestowed. Where we decide on the proper placement of capital letters tends to leave out and thereby diminish creatures like birds by grouping them without capitals. Our capital letter protocols trend toward elevating ourselves (our proper names and also like, “the English, the French, etc.), what we have made (like names of cars: Ford Taurus), and scientific endeavors (like genus names). This is another way that we set ourselves apart from the natural world. To remedy this in a small way, I am changing my writing to capitalize the common names of birds, like Mute Swan instead of mute swan. It is going to take some effort to break the habit. Perhaps I will appreciate and honor these creatures a bit more.