Nov., 1911 
DUCKS OF THE BARR LAKE REGION, COLORADO 
19,5 
The first, which has been mentioned above in connection with that of the 
Canvasback, was a mere burrow in the side of the musk-rat house, without any 
downy lining whatever, and only a few inches above the water level. On May 31 
it contained ten eggs, on June 8, eleven, two of which were Canvasback’s or Red- 
head’s; and on June 30 all but two Ruddy’s and one other egg had hatched, al- 
though one duckling had died while hatching. 
Meanwhile on June 8, the Canvasback’s nest was found on the opposite side of 
the musk-rat house and about four feet from it; and a new Ruddy’s nest containing 
three fresh eggs was found on top of the house, and about midway between the 
other two nests and somewhat higher up. This was a mere unlined depression in 
the litter composing the house, entirely without concealment of any kind, and the 
great snowy white eggs could be seen from a distance of many yards. On June 22 
the nest contained eight eggs, and on June 30 the set had not yet hatched. 
The third nest, found June 15, 1907, hardly deserved the dignity of the term. 
It was merely a depression formed by trampling a tuft of tender marsh grass down 
to form a flimsy platform just at water level in a dense cat-tail swmmp between two 
small lakes. When found it w'as over about two inches of water, and the under 
sides of the eleven fresh eggs were wet. A w’eek later the water in the swamp had 
risen slightly and the nest w^as deserted. This was about ten yards from the nest 
containing thirteen Redhead’s eggs mentioned above, and three of the eleven eggs 
it contained were indistinguishable from eggs in the Redhead’s nest. 
In all our visits to these three nests we did not see the birds leave a single time, 
although they sometimes swam about in front of us, some distance out on the lake. 
The apparent indifference of the brooding Redheads, Ruddys and Canvasbacks was 
in marked contrast to the devotion of the Teal and Pintails to their nests; and is 
very difficult to understand wdien the characteristic timidity of the last named 
species during the migration period is taken into consideration. 
THE RELATION OF BIRDS TO AN INSECT OUTBREAK 
IN NORTHERN CALIFORNIA DURING THE 
SPRING AND SUMMER OF 1911* 
By HAROLD C. BRYANT 
Fellow in Applied Zoology on the Fi,sh and G.ame Commission Foundation in the University of California 
WITH FOUR PHOTOS BY THE AUTHOR 
A S THE study of the economic relation of birds beeomes more and more im- 
portant, any information as to their use as checks in an outbreak of injuri- 
ous insects furnishes data of pertinent value. If it can be proved that birds 
floek to places w'here insects are abundant or even that the resident birds feed 
largely on those at any time most obtainable, their service as checks on outbreaks 
of injurious insects will be established. 
Professor S. A. Forbes in 1883 made a study of the relation of birds to an 
outbreak of cankerworms in an apple orchard in Illinois. The orchard was visited 
for two successive seasons and a number of the different species of birds present 
* This paper is a report of work done in connection with the investigation into the food habits of California 
birds in their relation to agriculture. This investigation is being carried on by the California State Board of Fish 
and Game Commissioners, and the present report is published with their permission. 
