You’re going to be hearing a lot about the Passenger Pigeon in the coming months. September will mark the 100th anniversary of the death of Martha, the last Passenger Pigeon. The extinction of this species, which went from numbers in the billions to total extinction in just a few decades, is a cautionary tale that we should never forget. While the extinction of the Passenger Pigeon is a warning about the toll that oblivious humans can take on nature, it has particular resonance for us here in California. Historically, there were three species of birds in North America that bred in huge colonies: the Passenger Pigeon, the Carolina Parakeet, and the Tricolored Blackbird. All three of these birds used to exist in such large numbers that it was unfathomable that they could ever disappear entirely from the landscape. And yet two of these species did, entirely. The one that remains, the Tricolored Blackbird, lives almost entirely in California, and is under grave threat.