segments. All transects start with seg¬ 
ment #1 on the eastern border of Montana. 
The transects are numbered consecutively 
from 1 through 12, south to north, start¬ 
ing at 45°30 f north latitude and extending 
to the Canadian border. Stratum 1 
40, 500 square miles in extent, was 
sampled with 80 segments of 18 miles 
each. Stratum 2, 33,000 square miles, 
was sampled with 113 segments. 
Water and habitat conditions 
Following a severe winter with heavy 
snow, the water conditions were good to 
excellent. Spring was about two weeks 
later than normal, but having arrived, 
accelerated at a fast rate. The rapid 
appearance of lone drakes indicated that 
the late spring did not have an adverse 
affect on the progression of the nesting 
season. Heavy rains the first week in 
May completed filling many stock dams 
and potholes that had not been previously 
filled from snow melt. This rain also 
created much temporary sheet water in 
wheat stubble north of the Missouri River. 
These shallow ponds, which covered 
shattered wheat from the last harvest, 
were very attractive to ducks of many 
species, particularly pintail and mallard 
deserter males. Therefore, a dispro¬ 
portionately high percentage of ducks was 
counted on water that would be present 
no more than a week or two unless heavy 
rains continued. 
Population indexes 
Stratum 1 had a mean density of 6 
ducks per square mile for a breeding 
population index of 256, 000. Mallards 
comprised 67 percent, pintails 15 per¬ 
cent, blue-winged teal 6 percent, gad- 
wall 4 percent, and several lesser 
species the remainder. 
Stratum 2 had a mean density of 14 
ducks per square mile for a breeding 
population index of 471, 000. In this area 
pintails were most abundant, 35 percent, 
followed by mallard 31 percent, gadwall 
13 percent, shoveler 6 percent, and blue¬ 
winged teal and widgeon 5 percent each 
(tables B-27 and 28). 
Discussion 
All water areas were recorded by the 
pilot within a one-eighth mile strip as to 
type and permanency. Four categories 
were designated: (1) stock dam, (2) 
natural pothole or lake (including tem¬ 
porary sheet water), (3) stream and (4) 
dugout. These were judged to be (a) 
permanent (lasting through the summer), 
(b) semipermanent (lasting until majority 
of broods are fledged) and (c) temporary 
(lasting no longer than mid-June). All 
duck use was recorded by water type and 
permanency (tables B-29 and 30). Each 
time a stream was intercepted within the 
survey strip it was recorded. Thus, if 
the same stream meandered back and 
forth across the transect, it was counted 
as often as interdicted. If a stream ran 
continuously within the eight-mile strip 
for a quarter or half mile, it was 
counted only once, however. 
In both strata, dugouts were not num¬ 
erous enough to be of great significance. 
The occurrence of streams is relatively 
the same in both areas. Stock dams in 
stratum 1 are almost twice as dense as 
they are north of the Missouri River. 
Conversely, potholes in stratum 2 are 
four times as dense as they are south of 
the river (table B-31). 
As one would suspect, permanent pot¬ 
holes and lakes had a much higher prefer¬ 
ence rating by ducks than any other type 
of water. Semipermanent and temporary 
potholes south of the river were much 
less attractive then they were in the north 
stratum, however. Permanent stock dams 
were somewhat more attractive in the 
south where there were fewer bodies of 
water than there were in the north, but 
properly built stock dams throughout the 
range land were readily used by many 
species. 
The ratio of stock dams to semiperma¬ 
nent and temporary streams in stratum 1 
was roughly two to one, whereas the ratio 
15 
