194 
THE CONDOR 
Vol. XIII 
CANVASBACK {Mai'Ha valisinerici) 
Probabh^ the most important feature of our field work at Barr was that of 
establishing- beyond question, the Canvasback, as a Colorado breeder. Although 
we made a special effort throughout the three seasons to locate nests of this species, 
one was all that we discovered, and judging from the few ducks seen, as compared 
with the number of individuals of the other species, we were no doubt very fortu- 
nate in finding the one nest. 
On May 31, 1907 we found a fine set of ten Ruddy’s eggs in an excavation in 
the side of a large musk-rat house. Upon returning to this nest on June 8, we 
found another and newer nest in the same musk-rat house containing eight fresh 
eggs of the Canvasback. This was also an excavation in the side of the house, 
much deeper than that of the Ruddy (the eggs being fully eight inches from the 
Fig. 6 (>. NKST AND KGGS OK RUDDY IN K.XPOSED POSITION ON TOP OK MUSKRAT HOUSE 
entrance), and higher above the water line. The cavity was fairly well lined with 
white down, quite a quantity of which was also scattered about the entrance of the 
burrow. A week later (June 15) the full complement of fourteen eggs had been 
deposited, and covered with a thick layer of down. The female was surprised not 
far from the nest and afforded us a splendid opportunity for identification. These 
eggs hatched on or about July 6. 
RUDDY DUCK ( Erismaiio'd Janiaicoisis ) 
Judging from the numbers of Ruddy Ducks seen throughout the three sea.sons 
on all the smaller marshy lakes, we should have found them nesting in considerable 
numbers, but three nests and a mixed set was the best that we could do. 
