We have a mated pair on our lake. We have been here 6 yrs, but the neighbor feeds them & thinks the female has been around for 20 yrs. The female has been alone for about 2 weeks. She would sleep in the shallow creek almost all day & night. She seldom comes in to feed anymore. She is now sleeping in the smaller part of the lake(lake is frozen). She can not stand well. She appears to be dizzy when she stands. She can not hold her head erect for very long ( a few seconds). The male has gone back to the larger part of the lake. Is this normal end of life behaviour? She is wild, so she would be extremely stressed if approached or captured. It is heart wrenching to see, but I do not want to interfere if this is the normal course of things.