Eared Grebe - Podiceps nigricollis

Right now (October 7, 2014) Eared Grebes are present in pretty good numbers, so I couldn't resist taking some shots of this one as it navigated around the Canada Geese and dabbling ducks at Las Gallinas ponds. When I got home I realized that the shots were interesting shots, as the 2 photos, taken 6 seconds apart, show how the features of a bird change with posture and activity.

First shot is a typical Eared Grebe posture, with a steeply sloped forehead, a peak of the crown above the eye, and the high-riding stern. 

Soon thereafter it began to swim faster, anticipating a dive, and the feathers became more streamlined. The forehead slope is now more shallow, like a Horned Grebe's, the peak of the crown a bit behind the eye, and the butt end is sleeker and low-riding.

I think this is young bird, molting into its "first basic" plumage. Note the amber/orange iris, as opposed to the redder iris characteristic of the adult Eared Grebe. The typical "first fall" birds are browner, but I imagine there is a fair amount of variation.