
38 
Nesting 
The nesting season began in late April and early May and was uninter- 
rupted by weather this year, except in the southern areas as noted above. No nest 
data of value was collected from either Area lor1I, but in the parkland areas a 
total of 203 nest histories were kept, 
One hundred and thirty-two nests were located on Area III. Seventy- 
seven or nearly 60 percent of these were mallard and scaup nests. The average 
clutch size increased in 1955 as did the nest success. Nest losses dropped 
appreciably raising the nest success to 45 percent as compared to 31 percent in 
1954, This condition seems to have been general throughout the Province, if the 
superior hatch from a population equal to or slightly below that of last year is any 
criterion. On Area III, the eggs in the various clutches were tested for incubation 
by the floatation method. After establishing the date of hatching, no further visits 
were made to the nests until the predetermined hatching date. In nearly all cases 
this method proved its accuracy and the observers confined themselves to two 
visits to each nest; one, when it was found, the second, when the eggs were hatch- 
ing. There is no way as yet of learning of the effect this may have had upon the 
hatching success of these nests, but it undoubtedly would work to their advantage, 
Of the known causes for nest predation, mammals (coyotes, ground squirrels and 
skunks) accounted for the largest number, crows and magpies, second and 
desertion, third. The preatest number were destroyed by causes unknown to the 
observer and usually took the form of'a total disappearance of the eggs, with or 
without any visible disturbance to the nest. Where several nests of a species were 
located scaup were by far the most successful (59 percent), with blue-winged teal 
(50 percent}, mallard (37 percent) and canvasback (36 percent) following in that 
order. 
On Area lV, 71 nests were located. It was much more difficult to 
find nests this year in this area than has previously been the case. This, in spite 
of the fact that the crew added one more man and two additional young dogs to the 
regular crew of two men and one dog. 
Mallard and canvasback nests comprised the greatest number located 
and the over-all nest success rose well above last year, 40 percent in 1955, as 
compared to 28 percent in 1954. The average clutch size declined somewhat from 
last year (7.2 in 1955 as compared to &.5 in 1954). Avian predation led in numbers 
of nests destroyed, (12), while mammalian predation and desertion accounted for 
the second largest number (eight each), Human interference resulted in the loss 
of five nests and may have been partially due to attempts to trap hens on nests. 
Several clutches of canvasbacks were injected with dye in order to stuly later brood 
movements, but this seems to have had no ill effects on the hatching of those nests. 
