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 Nov.,1911 DUCKS OF THE BARR LAKE REGION, COLORADO 193 The finest nest of this species which came to our attention was found June 15, 1907, in a dense cat-tail swamp between two small rush-encircled lakes. It was a beautifully built structure of dead cat-tail blades, mostly broken into small pieces, well built up above the surface of the water (which at this spot was only a few inches deep), deeply cupped, plentifully lined with down, and well concealed in the dense cat-tail growth. This set hatched on or about June 30. A photo of this nest appeared in the July, 1909, CONX)OR. Within about fifty yards of the nest found May 31, on June 8 we found one built in the midst of a solitary clump of cat-tails, containing two eggs of the Red- head and four of the Ruddy Duck. This was made entirely of dead cat-tails, and built in such a manner that the cat-tail clump entirely surrounded and covered it, Fig. 65. I'EST AI'D EGGS OF RUDDY IN BURROW IN SIDE OF MUSKRAT HOUSE affording good concealment. A week later this nest contained two Redhead's eggs and six eggs of the Ruddy, and on June 22, it contained five eggs of each. Whether this nest belonged to a brooding Redhead or a Ruddy the most careful stalking did not reveal, as the bird invariably skulked off through the dense cover before we were able to identify it. The peculiar manner in which eggs of more than one species were deposited in the same nest was a feature of special interest to us, and we tried persistently to unravel the mystery; but although we tried many different methods, we were un- able except in one instance, to flush the parent bird from any of the nests contain- ing mixed sets. In fact we did not flush any Ruddys or Redheads from nests ex- cept in the one case mentioned above.