Campus Mallard Nesting In Plain Sight

A mallard has been seen sitting in the same spot on campus for the last 10 days, under a bush on some ground raised a yard or so. First heard of it today, and went to see it. Turns out it was a male (I am told) that had been sitting there earlier, and it was a female, as shown in the picture, today. Judging by the down and the slight shaping of the ground just around her, she's probably nesting, aye? (Also, there was nary (a) reaction to the camera inches from her, other than a slight ruffling of feathers.)

If so, is it normal for male mallards to help warm the eggs also?