What is your definition of "species"? What is the transitive closure of your definition. Is "species" a property of an individual entity?
That's the question that the authors need to answer. As it stands now they say balcks and whites are different species. See my point? sloppy work or sloppy writing. Something needs to be fixed
Species...the usual, can interbreed with one another to create fertile offspring.
Different species...cannot interbreed and create fertile offspring.
I'm sure there are some biologists that can tighten this up a bit, but it is fairly clear.
Since the Goatsbeard observation, this one won't be a first observation of actual speciation. But it does appear to depend on the easier "prefer not to reproduce with" standard which creationists love to laugh at.
DK