Different colour, same species #1

When considering fauna, particularly birds we are generally pretty good at recognising different genuses. For example we can tell that an Eastern Yellow Robin and a Scarlet Robin are obviously related because of their physical form and their general behaviour. They are of the genus Petroica , rock-dweller, from the Greek words petros for rock and oikos for dwelling place. This reflects the island where the type specimen originates. Furthermore we infer they are different species because of their colour.

But colour is not always a good indicator of species. Brown Falcons (Falco berigora) are found all over Australia and are a common raptor in our district. They come in three colour morphs – pale, intermediate and dark. Pictured above is a pale morph Brown Falcon. Pictured below is also a Brown Falcon but a darker morph. The further you go north the more prevalent is the latter although all colour morphs can exist in all of the range.  The head markings are obviously different as are the colourations on the undersides between the two pictures. But are they different species?

The answer is no. A species is described as a group of animals that can mate and produce viable, fertile offspring. The definition has nothing to do with size colour or shape of the animal. That is why dogs, despite the many and varies shapes and shapes are all one species…they can successfully mate with each other.

As can humans…