This is Bailey when she was younger and I was building our addition I had these saw horses that were hollow tubing and the lizards loved to hide in the tubing. So Bailey with her sister Jessie who left us in 2001,also a golden retriever, would get on both sides of the saw horses when they saw a lizard inside and one or the other would blow thru the tubing to blow out the lizard and when they blew through it made a whistling sound. I heard this noise until I figured out where it was coming from. It was the dogs after the lizards. If the lizard didn't come out they would stand there until I helped them.