My GSP has suddenly taken on the habit of jumping our 4 ft 1/2 ft fence that encloses our backyard.He does thisat night when he is let out even for a very short time. He doesn't go far and he does come back very quickly when called. But this is a worrisome problem because there is coyotes around and they are very previantly this time of year.What might I do to solve this problem?

I did this (reinforced a fixed fence w/electric) -- works great.  I was concearned when we picked up our puppy we saw his dad jump (on command) a 4 foot fence and clear it by about 8 - 10 inches.  If you are going with a fixed fence I would go with 6 feet -- anything less is tempting fate.  You COULD train them not to do it with a remote trainer, but it would be easier to do an electric fence.