My grandson and I recently covered pine cones with peanut butter and birdseed and hung them with cotton string from a young oak tree. Several cardinals feasted from them on the first day. Later, after a heavy rain, I noticed a rwb was not able to reach the pine cone from the branch; the string had lengthened after being wet, I suppose. I was astonished as I watched the rwb bend his head down and pull the string up. He then held the string with his feet and reached again and pulled it up two more times. Each time, he would step on the string with his feet. It only took him a few seconds to do that, and then he ate his fill and flew away. I thought it was really neat how he handled his problem.