"Tam/WB2TT" wrote in
:

....
Heliax or semirigid coax might cause them to give up. Especially the
latter. 75 Ohm stuff would be fine for the 4:1 balun, because you
actually would want it to be 100 Ohms.

Birds attack Heliax at this location, but less so than vinyl covered
coax.

Sulphur crests are a particular problem:
http://en.wikipedia.org/wiki/Sulphur-crested_Cockatoo

Nevertheless, Heliax is pretty much unaffected as they usually rip small
holes in the vinyl sheath which doesn't affect the cable due to the solid
external conductor, and even when they punch through the copper shield,
water will not soak throught the cable due to the closed cell foam that
is bonded to the shield with adhesive.

There might be more creative solutions Alan. I stopped feeding birds when
Sulphur Crests starting congretating en-masse and before they started
eating the house.

Owen