To echo others: get a dome. To reinforce what Mike B said: keep it as far from fences and trees as you can.
Anti Squirrel Dome - I got mine from Amazon. One of the cheapest.
Metal pole - I used a metal clothes (wardrobe) hanging rail from a DIY chain; probably B&Q.
Garden clothes dryer spike - I think I bought one from Amazon, but DIY chains have them
This is mine, covered in starlings. I moved it twice. Originally it was 6 feet (1.8m) from a 1m high fence. Squirrels jumped the gap effortlessly. Moved the feeder out a foot. Squirrels just made the leap. The feeder is now about 9' (2.5m) from the fence.
An explanation about the Stalag fortifications. They were designed to keep Wood and Rock Pigeons off the feeder. Wood pigeons would stand on the dome and peck food out of my hanging feeders. The would land on the top feeder, shimmy down the supports, then empty the food in the top, flat in about 30 seconds. The fortifications allow in Jays, Magpies, Blackbirds, etc but keep the pigeons out. Thus food lasts a few days rather than half a minute or so.
We have three GSW visiting. Two parents and a fledgling. I make bird seed towers - your basic bird seed cake mixture, but formed into a tower. My mixture is finely diced (3mm-5mm) lightly toasted bread (by toasting the bread you stop it from squishing up when dicing it) and standard song bird de-husked seeds - sans wheat if possible. The whole lot molded into shape using an old shampoo bottle, cut lengthways (but not all the way through) and opened out. BTW Long Tail Tits love this mixture. They only feed in winter months.
The GSW starts here
It then shimmies down the vertical supports. It can feed from the top feeder at this point, if it chose.
It then transfers to the bird seed tower - in a suet feeder.
However, we have a stroppy, belligerent Starling, which took great exception to the GSW. They have many a ding-dong battle.
In this instance, the GSW loses its balance; though in reality they are finely matched.
GSW recovers its balance, and there is a truce.
90% luck, 5% field craft, 5% camera skills.
