Bird brain is a misnomer
The study contrasted its white noise which interferes with birds’ ability to hear critical signals with the previous deterrents (loud noises, predator sounds, fake hawks, alarm calls). Bird brain is a misnomer, for ornithologists have shown that their subjects are quite good at learning. Over time, in true Pavlovian fashion, the fact that the “predator sounds” do not correlate with threats results in the birds’ ignoring that sound. Since the W&M system continuously negates hearing, its strength as a “net” does not appear to diminish over time.