Ask the Swan Specialist

Swan behavior, normal or worrisome?
Date: 10 October 2014

Kayak on the river and I'm familiar with lots of different words. Today there was a swan floating alone with his head resting on his back in the middle of the river. He didn't move when I paddled right up next to him but eventually he did reluctantly. He moved along slowly his stride sort of an even looking in the water. But most of all he was alone which I don't usually see on the river no other swans in sight. Could he be injured or sick?
Will send photo