Brood Breakup 
Sufficient data were not obtained on mortality and brood breakup to 
enable any definite conclusions to be drawn. A portable trap was developed 
in an attempt to capture and mark class Il broods eo that their later 
behavior coulA be etudled. With further modification 1t should prove use- 
ful for the capture of river duck broods. However, the genson wis too far 
advanced and few broode remained by the time it wae completed. Two young 
captured by thig means were banded anc marked with airplane dope. They 
were not gsé#n again, 
Such data ap were obtained on trood brealup indicate there is zreat 
feasonal, apecific, and individual variation in the length of time the 
brood stays together. Diving duck hens left their broods before they were 
ready to fly. By the middle of August few were geen on the area although 
many of the young were still in class II, River ducks, on the sther hand, 
stayed with their young for a longer period. An extreme example is probably 
furnished hy a mallard brood which was found together 13 daye after the 
firet of the young were geen to fly. 
Productivity of Area 
Deta on the productivity of the area reduced to a square mile basis 
are shown below. 
Species Fairsjsa, mile Brooda/eq. mile Ratio: broods ir 
Mallard a 
Canvashack 1 
Blue-winged teal 1 
Baldpate 
Ruddy 
Redhead 
Fintail 
shovel er 
Green-winged teal 
Gt Awall 
Unidentified tenl 
Unidentified 
Total 8.1 
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a 
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a 
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ee oR A en om 2 UD 
* I 1 
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iM tf onen on th =o 
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1 
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206 
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The breeding pair count was made incidentally to the first search for diving 
duck nests during the period from June 12 to 18. Due to the latenese of the 
ceagon the figures are not completely accurate. However, the total figure 
neTees closely with data obtained by William Kiel on & standard transect 
bounding two sidee of the area. The number of breeding faire was calculated 
aa follows: Each lone drake, each lone hen, #ach pair and each brood geen 
wan considered ta represent a pair of breeding birde. Since this count was 
made at the peak of the incubation perlod for mallards, pintaille and canvas- 
backs, many incubating hens of the two former species were undoubtedly miered. 
Moet of the canvasbacks were probably seen on or near the nest. The basie 
for the brood count was a census made with the ald of Eugene Possenmaier of 
the Delta Station, duly 13 to 17 by thorough drives around the margine af all 
potholes. Early hatched class II breoda seen June 12 to 18 which were flying 
‘e 
