From an evolutionary perspective - there are no arbitrary barriers between organisms. If I got all living things together in a room and pointed at one of them I could, in principle, point to something else that is the same species as that one. Then I could point to something else that was the same species as the second one. And I could keep pointing at things which are the same species as the last one moving from one organism to the next until I've moved from an ostrich to an orchid.
This is because all are related to each other. It is only the fact that most animals that have lived are now dead that means we can't do this so easily on earth.
But nobody makes any claims about what a species is or is not capable of so an absolute definition of it is less important.
Creationists do make claims about 'kinds' but are unable to determine what is or what is not a 'kind'.
Am I a different 'kind' than my father?
Is a mule a different kind than a donkey?
Is Drosophila paulistorum (fruitfly) a different kind than Drosophila melanogaster (fruitfly)?
If we observe one population coming from another and the 'daughter' population is unable to interbreed with the 'parent' population: does that mean a new kind has been created?