How do birds identify food?

I would point out that humans, also, primarily find their food using visual clues. And that works pretty well for us

I know a guy (on line) who trains birds to ignore the berries on his berry bushes by hanging fake, inedible berries on them throughout the growing season. He has beads that look like raspberries and blueberries, iirc. Others have asked him how convincing the fake berries need to be, and his answer is that they should fool a human looking at the bush.

Emphasis added. Worth noting that while this can be strictly true (for example certain owls at least seem to have enhanced UV sensitivity at night), it tends to be a little exaggerated as a meme. In particular there is popular idea that owls are near-blind during the day which is absolutely not true. Even excluding almost entirely diurnal species like Burrowing Owls or Snowy Owls, many more nocturnal species can and will occasionally be fully active hunters in the daytime like Barn Owls and Short-eared Owls. Since they also have superb hearing, super-acute vision in the daytime is not as necessary as it would be to an eagle, but they can still see okay in full light.

Yes, there’s nothing like a giant barn owl buzzing your head in the late morning to wake you up. I don’t mean to suggest that they’re blind as well, a bat (who have okay vision as well). But among other things, they have a higher rod:cone ratio than other birds, or diurnal mammals.

There was an article or thread around here regarding how birds “find” food - such that when you put out a bird feeder where there was none prior, within a few minutes birds have found it and are chowing-down.

I do wonder about the question of this thread, tho - how do they “identify” what’s edible. If you watch a barnyard chicken, or our local wild turkeys, they seem to be pecking at bare ground or gravel, and I wonder what they managed to identify that seemed like food to them. I can understand the turkeys scratching at ground-cover like bark and locating insects or what-not, but sometimes they are pecking at the concrete gutter, or even in the middle of the street, and I have gone over to where they were to see what it may have been - nothing there. Seeds of some sort, I suppose.

I ran into that bit of advice years ago in a farming discussion; but ran into the problem when I went to try it out that I couldn’t find convincing looking fake fruit made out of anything that would stand up for any significant length of time in the weather, at least for any remotely reasonable price if you wanted more than a couple of samples.

A friend told me it took a couple of months for birds to find her new bird feeder. But when she added another, in a place where there had been a feeder several years ago, they found it right away.

Sure, but birds can’t google “good sushi restaurant in Soho” on their phone.

Birds wander around looking for food sources, especially seed and fruit eating birds where new sources may become available and old sources become exhausted. And once one or a few birds find it the activity attracts more.

A woodpecker pecked a hole in a wall at my employer’s building. I’m not sure what the material is, something resembling fiberglass or greenboard. No food in there but a nice place for a nest. It took blocking the hole time & again before Woody got the message and moved on.

I don’t know about chicken specifically, but many birds peck at gravel because they are eating gravel. Many but not all species have a crop and gizzard. They pass gravel and grit into the gizzard and use it to grind their food.

Either eminent domain or one of those easements.