A simple solution is to screw a standard suet cage on the underside of
a square of plywood, about 6 inches to a foot bigger all around than
the suet cage, suspended from the corners so that it hangs
horizontally, and the only access to the suet is upside down.
"Store-bought" versions exist which have gable roofs, with the suet
being accessible through a wire mesh on the underside. Woodpeckers,
nuthatches, and chickadees all master it instantly. Starlings are not
good at getting, or hanging, upside down. They can do it if there is a
branch below that they can use as a springboard. Same with crows. I do
have a couple of STJA which have figured out how to get upside down
(one first, then the others), using the springboard approach. It works
best if it hangs freely so they have to fly up to it and turn upside
down.I was also surprised to see a DEJU and a SPTO learn how to do it.
Last note - sometimes the desirable birds find it more quickly if it is
hung on an angle, then lowered to horizontal when they find it, to
deter the riff-raff. Contact me off-list if you would like to see a
photo.

Bruce Whittington
Victoria BC
Mailto: fieldnat at pacificcoast.net