It is unclear what your complaint is. As the second quote states, you only need a sample size of one to prove that a certain ability can exist. You just cant say much about how widespread the ability is.
Thanks for the clarification. That seems fair, I suppose the title of the article gave me the impression that they were claiming such an ability would be widespread in all crows (despite the study being done on two carrion crows), when in fact it seems the intention was to state that the ability can exist in any crow given that they proved it exists for those two specific crows.