Sometimes a gourd is strictly for the birds...
Use any large, fully-ripe hard-shell gourd (squash) that
is adequately dried - i.e., the seeds rattle around inside!
The pear-shaped ones are the best for bird feeders. They’re
often called "bottle gourds", because Southwest
Native Americans use them for water bottles. You can cut the
birds’ entry hole (or holes, perhaps, for a feeder) with a
knife before the gourd is dry, or you can carefully drill it
out with a Dremel tool or tiny saw afterward. Hollow it out
as best you can once it’s dry. Punch/drill 2 holes in the
top and loop a leather thong through it to hang it by.