A. Birds can hear well.
B. Many single-lens reflex digital cameras make a loud sound (noise) immediately after the shutter release is pushed.
C. See photos below.
The cardinal, a female, was sitting on a feeder post on our deck before prior to snow seed foraging. I was inside, a double pane of glass between us, like 10 feet. I took four or five photos, bird on the post, bird with seed. On shot number six the bird became very alert, crest upright, eyes snapped toward me. You can see what happened as I took photo seven.
This isn’t the first time this has happened to me. Hardly. I should have kept all the before/after pairs of photos. Before the bird heard the camera, looking at whatever kept its attention. After the bird heard me, saw me, and left me.
You probably know this: Single-lens reflex 35mm cameras allow you, the photographer, to see your subject with a mirror placed just behind the lens. The mirror shows you what the lens sees. When you press the shutter release, the mirror snaps up, allowing light to reach the digital sensor (i.e. film). And then the mirror returns to position with, in my case, a loud and annoying clack.
I work with a newer model Nikon digital camera that I considered expensive when I bought it. I knew about the clack. I was unwilling to spend twice as much or more for a high-high-end model that made far less noise. You’d think that camera manufacturers could find an inexpensive way to solve this problem.
Some birds either don’t hear the noise or don’t mind. This cardinal heard and cared. I was impressed. Small benefit: I really do like that snapped-to crest.