Black-necked Grebe; Podiceps nigricollis
Not a good photo of this extremely beautiful bird. But it was rather difficult to take a picture of its black feathers against the bright morning sun and on the sparkling water.
My friend Matvey discovered this grebe on Vyrlitsa lake in Kiev, Ukraine and informed me. A few days later I visited the lake and saw it too - a pair of them, along with a lot of Great Crested Grebes.