All well and good but RE "An ESU, or “evolutionarily significant unit”, is a population of organisms that is considered distinct for the purposes of conservation."- It is worth noting that this is nothing new or unusual. I submit that, regardless of so-called species, any parrot population can exist in wildly varying climate and weather conditions. As do Alexandrine parakeet existing for decades in such climate regions as Cologne, Germany, Stuttgart, Germany and parts of London, UK. These birds all have. been surviving winters in substantial numbers for decades - entirely due to the release of captives into the outdoors in the affected areas. So it is possible for all these cockatoos to do the same thing- survive outside their original range. A huge colony of conures has existed in San Francisco for decades as well. A mexican parrot species has existed in Pheonix, Ariz. and has become cactus nesting for the lack of trees. (wood peckers do the cavity excavation in their own nest building routines). Rock pigeons began as a Mediterranian species but are now international and intercontinental. Human beings are the agents of propagation in many cases. Tall buildings provide the preferred nesting areas.

Much has changed since the days of Darwin. So should we.