The grackles, blackbirds, crows, cardinals all learned very quickly to eat the seeds.  They put one foot on the dipper and the other foot in the seed hole.  Therefore only half their weight is on the dipper level.....so it doesn't dip and flip them off.  And the little birds were being chased away by the bigger birds.
  My solution was I returned the Droll Yankee Dipper Feeder and got a wide diameter cage and put my tube feeder inside this.  The small birds hop in an out and eat .....while the grackles at first would go round and round the cage trying to figure where they can get their head through and get to the seed, but to no avail as their head can't reach in far enough....and they give up and pick up any ground droppings.
The grackles, blackbirds, crows, cardinals all learned very quickly to eat the seeds. They put one foot on the dipper and the other foot in the seed hole. Therefore only half their weight is on the dipper level.... . so it doesn't dip and flip them off. And the little birds were being chased away by the bigger birds. My solution was I returned the Droll Yankee Dipper Feeder and got a wide diameter cage and put my tube feeder inside this. The small birds hop in an out and eat.... . while the grackles at first would go round and round the cage trying to figure where they can get their head through and get to the seed, but to no avail as their head can't reach in far enough.... and they give up and pick up any ground droppings.