Hey Mike, I have ran into this same issue as well. What I did was set up a game camera on a t-post (I have my feeder on locked private land where no one can steal it) and put the sensitivity on high, as I suspected birds as well. Once I was able to confirm it was birds and not any other sort of varmints, I saw where they were landing on the pvc feeder and I installed some very small makeshift spikes out of finishing nails. I made sure that they were short enough that if the deer stuck there nose or mouth in the opening it wouldn’t stab them. The nails were there just to deter the birds from landing on the opening making it very inconvenient for them and their supposedly free meal. I left the camera there for a week afterwards and I was shocked at how well it worked.

I hope that helps a little for you!

Chris

I have made two PVC deer feeders and attached them to trees.
High enough to discourage raccoons, low enough for deer.
The corn is going down in the fill tube. But I believe its birds!
No deer tracks under feeder.
Can’t figure out how to deter the birds with this feeder.
Thought about putting flap over feeding oriface.
But doubt deer are savvy enough to lift it to feed.
Any ideas?