Hey Kathy your Hawk may be standing on a somewhat collectable antique power line insulator, although this exact type is fairly plentiful. The rarer and highly sought after ones either screw into wooden pegs or are made of clear or tinted glass. This one looks like a more available (~$10) ceramic type with a steel peg.
No doubt there are some (many) of the glass insulators around here. I've probably shoved them to the back of a cupboard downstairs with all the other stuff I have no idea what to do with.