Due to the mild weather there seems to be far fewer birds visiting my feeders this year. I'm usually onto my 2nd sack of sunflower hearts by this time, & if you look at the shrubs in your area you'll probably see they're full of berries.
I bought one on Sunday and about 15mins after putting it up saw a cheeky little Blue Tit on it. I was pleased as punch but unfortunately haven't seen a single birdie on it since. Must admit I was amazed when I saw the Blue Tit on it so soon, but gutted since.
Is it a brightly coloured bird feeder. ?Birds in my garden will eat from the dark green feeders but won't go near the bright red one. Or it could be the reflection from the window that is putting them off from using it.
Excel, I have two window feeders, one was visited after about 10 days and the other in a different room with a different aspect took nearly 3 weeks. Both now regularly visited.