This may sound nuts but I saw a gbh swimming to the bank and go into some really thick brush along the shoreline. I have never seen them swim and I have spent a lot of time on the water. There is no way the bird was walking in the water because its close to 6 foot deep where I first saw him. And I attempted to roust him from the thick brush by my side by side and then by boat but was not able to find him or her, so where do they have their nest? Do they nest in thick brush or in the nearby trees? Was this a ghost gbh, it did disappear in the thick brush? I have two or three at the pond most everyday.
