Number of hummingbirds PIT tagged at Sites 1 and 2 in Northern California and Site 3 in Southern California.

Open feeders are defined as feeders that did not have radiofrequency identification equipment. Feeding stations are defined as those equipped with radiofrequency identification equipment to detect passive integrated transponders.开放式投喂器（Open feeders）系指未配备射频识别（radiofrequency identification）设备的投喂器；投喂站（Feeding stations）系指配备有射频识别设备以检测被动集成应答器（passive integrated transponders）的装置。