37 
One mallard brood which was observed repeatedly was accompanied by the hen 1 
days after the first of the young were seen to fly. This hen was still feigning 
injury even though the brood was well able to escape. A green-winged teal hen 
also was seen accompanying a group of flying young presumed to be her brood since 
one of a corresponding age and number had been repeatedly observed on pothole No. 
33. No broods of diving ducks or ruddy ducks were seen accompanied vy hens after 
they appeared ready to fly. 
Most broods appeared to remain as units from the time they were deserted by 
their hens until they were ready to fly, very few young having been observed as 
singles. Desertion by the hen was apparently only the first stage of brood dis- 
persal which was usually not complete until after the young had flow. 
Age of Attainment of Flight -- Since three broods were observed from the time 
of hatching until they were judged ready to fly, it was possible to gain some infor- 
mation on rate of growth in the wild. 
A canvasback brood hatched June 30 reached Class II on July 25 at the age of 
26 days. By August 1), at the age of 6 days, it was Class III, and by August 22, 
at the age of 5 days, the primaries were almost fully grown and it was judged ready 
to fly. . 
A redhead brood hatched July 2 reached Class II on July 30 at the age of 28 
days, and Class III on August 20 at the age of 9 days; on August 27, when it was 
56 days old, it was judged ready to fly. 
A baldpate brood hatched July 5 reached Class II on July 28 at the age of 23 
days. It was not clear when it became Class III, but it was judged to have reached 
flying age by August 21 at the age of ]\7 days. 
From these data, it appears that birds in the wild may require less time to 
reach flying age than do birds in captivity as indicated by Hochbaum (194), who 
found that canvasback require 63 to 77 days, redhead 63 to 77, and baldpate 5 to 
58. 
VII. PRODUCTIVITY OF THE AREA 
Count of Breeding Pairs -- Since the count of breeding adults was made late in 
the season, it was necessary to tally all of the following categories as pairs: 
(1) Observed pairs, (2) lone drakes, (3) lone females (presumed to be incubating 
females absent from their nests), and (4) brood hens. Care was taken to avoid 
duplicate counts by eliminating any birds which had apparently been already counted 
when flushed from a previously censused pothole. 
Calculation of Broods Produced -- The basis for calculating brood production 
was a count made during the period July 13 to July 17 with the aid of E. F. Bossen- 
maier. Excellent weather prevailed during this period and it was felt that most 
broods were seen. Added to this count were two mallard and two pintail broods 
seen during the first run (June 12 to June 18) which were old enough to be flying 
by the later date, Three baldpate, four teal, one mallard, two redhead, and four 
ruddy-duck broeds hatched after July 17 were also added. The total represented the 
sum of three instantaneous counts and was not the sum of all broods seen. Because 
of movements as discussed previously, the latter figure would represent all broods 
which had been seen visiting the area. The mumbers of breeding pairs and broods 
reduced to a square-mile basis are shown in Table 19, 
