I've gotten pretty far with the local jackdaws. Depositing items I leave on the platform is no longer a challenge for them, but they still haven't figured out that they can bring stuff to deposit on their own.

To try and bridge this gap I added a conditioning stage between 3 (deposit provided on platform) and 4 (no deposit provided), so there are now 6 stages.

The new stage calls for placing items for deposit near the platform to get the birds used to the idea that they can bring stuff to the platform. I've added a wooden arm to the stand  to hold a PVC cap with some bottlecaps and a few butts in it. It appears to be working - I've seen them bring these to the platform and deposit them a few times already.

After a week or so I will put another end cap with bottlecaps and butts on the ground near the vending machine. Hopefuly this will lead to some progress.

New list of stages is below.

Conditioning Stages
0 - Small amount of food in the area you will mount the vending machine to attract birds (~1 week)
1 - Food Provided, Timed Dispense, Deposit Provided (1-2 weeks)
2 - No Food Provided, Timed Dispense, Deposit Provided (2-3 weeks)
3 - No Food Provided, No Timed Dispense, Deposit Provided on the Platform (3-4 weeks)
4 - No Food Provided, No Timed Dispense, Deposit Provided Near The Platform (TBD)
5 - No Food Provided, No Timed Dispense, No Deposit Provided (GOAL!)