Another important point is that determination of a genus or species is a matter of human categorization and definition.
We can continue defining sub-species, and sub-sub-species, etc., on the basis of the most arcane and trivial distinctions (i. e., this group of pigeons has a yellow rather than orange beak).
The same subjectivity applies to "eco-system" and "habitat" definition. We can arbitrarily define such "systems" and "habitats" around anything at all (i. e., "this pigeon is native only to the 'eco-system' in Avatar's backyard"), and expand it geographically by whim (i. e., "we need to establish a ten-square-mile protective buffer zone for the pigeon's habitat around Avatar's backyard").
By this subjective means, those who want to stop human activity ANYWHERE can simply, arbitrarily define some new "threatened species" and "eco-system" or "habitat," to their hearts' content, to wit:
"WE FACE A THREAT TO OUR BIODIVERSITY. Due to [fill in the hated human activity], we're about to lose the Yellow-Beaked Ruffle-Feathered Chicago-Based Pigeon...leaving an unnatural 'imbalance' in the greater Chicago 'eco-system,' with a corresponding over-population of ORANGE-Beaked Ruffle-Feathered Chicago-Based Pigeons!
"THIS IS A NATIONAL CRISIS, WHICH THREATENS THE WHOLE DELICATE GLOBAL 'WEB OF LIFE'! WE MUST DO SOMETHING!
"Therefore, to protect the threatened [habitat, species, eco-system], we must immediately halt all [fill in your most disliked human activity]. So today, the [Sierra Club, Wilderness Society, EPA, National Park Service, or your preferred green entity] announces a [lawsuit, new regulation, tax, restraining order, or your other preferred means of coercion] in order to [remove, excise, curtail, slow, halt, obliterate, etc.] any trace of [human presence, or some nefarious human activity].
[Typical afterword for fundraising letters:]
"To help us fight this dire planetary threat, please send your highest donation to [name of green entity]. Thank you!
"(Signed),
"[Name of scientifically ignorant celebrity desiring the public cachet of moral significance]"
It's on the basis of this arbitrary criteria that the Endangered Species Act, and government regs about insuring "biodiversity" and "eco-systems," are being used to shut down businesses like farming, ranching, and logging, to confiscate private property, to order people to stop moving dirt in their own yards, etc., etc.
When are people going to wise up to the fact that they are being played for suckers? That this entire green enterprise is nothing more than a scam to grab power and control over everyone's lives and property?