There were still quite a few juvenile Yellow-bellied Sapsuckers at Hasty Brook last weekend but I didn't see a single adult. Are the adults moving south all ready? This young one spent quite a bit of time on the thistle sock. I've never seen a sapsucker on any kind of feeder before, seed or suet. Quoting Sibley:
"Sapsuckers mainly eat the inner bark of trees, lap sap that oozes from small wells that the birds drill in a tree trunk, eat invertebrate's trapped in the sap produced at these "sapsucker wells," and also flycatch invertebrates."
When this bird first inspected the thistle sock, he (she?) seemed to give it a few whacks, burying its bill deep into the seed.
After some time it would probe the seed without the force, gently bringing out thistle, which it proceeded to eat. It occurred to me that the bird might be probing for insects, but I had just filled this sock with fresh seed an hour before so I'm certain it wasn't swallowing insects.
I was glad to have the type of sock with the bigger holes or I'm sure he would have enlarged the holes, tearing it.
Has anyone seen this foraging behavior in Yellow-bellied Sapsuckers before?