This is a remix. In the original feeder sunflower seeds stuck because the neck of the bottle is too narrow. I used a bottle with wider neck - outer diameter 36mm (measured without thread), you can see it on the pictures.
Use milk bottle thread d36.stl for checking that this feeder will meet your requirements.
Update
v2 (bird feeder v2 d36.stl) - stronger version. Heavy birds like three doves at once can break a normal feeder. So I strengthened it.
bird_feeder_d36.stl | 1.0MB | |
bird_feeder_v2_d36.stl | 2.0MB | |
milk_bottle_thread_d36.stl | 274.7KB |