Untitled Sighting

It was late afternoon/ early evening in September and we were sitting on our pier watching our dog, Sofie, swim and retrieve tennis balls. I had my binoculars to look for loons when we heard what sounded like a large tree branch or a large animal stepping on a downed tree across the lake from where we were sitting,  approximately 450 feet. I was excited because I thought I was finally going to see a bear. Next there was a loud splash in the water that sounded like a very large animal or something large being thrown in the water. I looked across the lake with my binoculars but didn’t see anything, so I assumed the activity was in the marsh beyond the tree line. During this time my dog got out of the water and sat at the end of the pier next to us. She appeared nervous and kept staring across the lake toward the sound. Over the next several minutes we heard three separate wood knocks like someone was hitting a baseball bat against a tree. At this point it was dusk and our dog was visibly upset; she left the pier and headed back to our campsite so we followed her. Of note the land across the lake is state land, undeveloped and predominantly heavily wooded with a large marsh area beyond the trees lining the lake. Just wanted to share because I don’t know of any animal that knocks and I’ve never witnessed my dog that upset.