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Nest hunting was carried out mainly for the purpose of trapping and 
marking mallard hens and newly hatched broods so as to obtain data on renesting, 
movement, and development. The highest nesting density for a large area was 
99 nests of nine species found in a 0. 75-square mile area between May 9 and 
June 22; 57 of the nests were of mallards. Natural predation appeared to be 
negligible. Many early nests (mainly of pintail) in stubble that was reseeded this 
year were probably wholly or partly destroyed by seeding operations which were 
underway by May 10. 
The first mallard brood apparently hatched about May 17 and the last 
about August 29. The peak period for the first mallard hatch was May 25 to 
June 7--about two weeks earlier than in 1954. Average clutch and brood sizes 
were as follows: 
Species Incubated Nests Class | Broods 
(1955) June 13-18, 1955 June 12-July 2, 1954 
Mallard 9.9 epgs (84 nests) 6.2 Y. (152 Br.) 6.4 ¥. (46 Br.) 
Pintail 8.9 eggs (34 nests) 4.8 Y. ( 53 Br.) 5.6 Y. (25 Br.) 
A 246-square mile observation-type transect (not beat-out) of sloughs 
with little or no emergentyegetation was made between June 13 and18. It gave an 
average of 4.2 broods per non-emergent slough and an over-all density for sloughs 
of 0.6 per square mile. Five of the 79 non-emergent sloughs accounted for 156 
broods; 28 were recorded as unoccupied. The following counts, made during 
banding drives on open sloughs, further illustrate the clustering of broods: 
Date Location Area Young & Hens - All Species 
June 29 SE Pinkham 65+ acres 600+ Ducks 
July 6 mn 554°" 2404+ =" 
July 13 S Marengo 100+ " 300+ " 
July 14 SW Flaxcombe 60+ " 2754+ " 
July 15 SW Fairmount 30+ 270+ ' 
July 17 SE Smiiley 160+ " 900+ " 
July 22 NW Eatonia 140+ #" 285+ ="! 

Considering water area alone and the fact that the duck figures are 
one day (rather than full season) counts, production for the square mile of water 
covered by the above seven sloughs was more than 400 broods. Larger water © 
areas, however, were not found to produce ducks in such abundance. A careful 
aerial coverage of the shoreline {64+ miles) of three large sloughs (17+ square 
miles) in the same area on June 24 disclosed signs of only 48 broods. 
