Main thing is getting him before he becomes food for the hungry predators or gets frozen in place and then becomes food. I rescued 3 drakes from our river down below but it was in summer. I spent about a week winning them over and they were hungry. I used cracked corn because most ducks love it and it's a surefire way of winning them over pretty quick. I set up a dog x pen at the river kept one side open the side facing the river. I started putting the cracked corn down before putting up the x pen once they were looking for me with food I waited till they were out in the water after eating an set up the pen then I started by putting the cracked corn outside of the pen on the ground and gradually over a few weeks moved it inside till it was clear at the back so they had to walk all the way in. [These drakes couldn't fly] Once I got them inside and eating I closed the open end and walked in and picked each one up placed them into a dog crate and brought them home. I rehomed.