Strange question asked by my daughter this morning. She was looking for some bird food for the birds that visit her garden. She picked up some bird seed and asked 'how do birds know there's food out for them?' I couldn't answer her but thought someone on here could! So, do birds have a sense of smell or how else do they know where food is?
if you are talking about garden birds they garden hop and pick up what they find there.
In our old garden everyday twice a day there would be a huge flock of around 12-15 small birds like sparrows and some tits and you could see them coming up the road over the garden fences. It was quite amazing really.
Starlings are the same they send out a few scouts who then presumably report back to the main flock who then descend on any food available.
So they don't "know" there is food there but if you put out food regularly then your garden will get visited by the gang.
I think its a skill thats passed down through generations.
In my observations I'v seen parent birds accompanied my their young at places where food is available and as a result the young will learn from the adults.
I think that instinct plays some part in this too.
I have a robin who will take from my hand but usually I put his treats in the window box. I can actually give a special whistle and he will arrive and have also known him to hover outside an upstairs window at me as if to say come down and feed me. In answer to your general question, I believe birds have excellent eyesight.
It is learned behaviour over a period of time that gets passed down to the young.
Where we live we only feed wild birds occasionally otherwise they become dependent and forget how to forage for themselves.