12 
Although from the standpoint of vegetation, the semipermanent potholes 
could be put in one of the above classes, the difference in the stability of 
the water supply had such importance for ducks that they have been grouped 
separately and have been placed in types similar to those in group A. 
However, owing to the absence of open water, their submerged aquatic vegeta- 
tion was much reduced, 
Bl -- The sedge-whitetop semipermanent potholes were almost identical 
to the permanent except for the lack of open water and consequent scarcity of 
submerged aquatics. Lesser duckweed grew in many of these even though some 
went dry during July and again late in August. Other submergent aquatics 
were rare, Some areas of this type were completely overgrown with nearly 
pure whitetop while others supported pure sedge or mixtures of sedge and 
whitetop, In most cases the transition from aquatic species to prairie was 
similar to that of the permanent areas. However, there were cases where the 
rapid recession of water in the spring permitted cultivation beyond the natural 
margins and the transition was lacking so that pure whitetop was directly 
adjacent to small-grain crops, 
Type B2 -- Semipermanent cattail potholes differed little from the 
permanent type, except that there was generally a considerable growth of 
softstem bulrush mixed with the cattail, 
Type B3 =~ These differed markedly from Type A3, as they contained no 
hardstem bulrush. They supported a mixture of softstem bulrush, cattail, and 
spikerush, in which the bulrush was most prominent. The cover was generally 
somewhat sparser than in Type B2. 
Type Bh -= The semipermanent potholes with scattered vegetation were 
comparable to permanent waters of the same type. Burreed was often abundant 
as were water parsnip, water plantain, spikerush, and slough grass. Some of 
these areas supported predominately spikerushes and rushes with some softstem 
bulrush, At first glance some appeared to be temporary areas; but when aquatic 
species were present, they were classed as semipermanent. 
Group C -- The temporary waters have not been broken down into types. 
They varied from islands of willow in cultivated fields through several forms 
of wet meadow to cultivated fields which were flooded in the spring and after 
heavy rains. Since these areas had a certain value to waterfowl they have 
all been considered potholes, although they have not been shown on the map 
of the study area, 
Group D — Dugouts were artificial water areas most of which were dug 
during the drought years with the aid of the P. F. Re A. (Prairie Farmers! 
Rehabilitation Act). They were about 170 by 60 feet in area and usually 
10 feet deep. The soil was renoved by means of drag lines and piled up in 
high spoil banks on two sides, Two on the study area were dug in places 
where there had previously been potholes and have been flooded over since 
the drought. The dugouts themselves supported little vegetation other than 
water milfoil near the sides and some sparse emergents, generally sedge and 
spikerush, along the banks. 
Vertebrate Species Found in Potholes 
Waterfowl seen in the area were Mallard (Anas plat chos), Gadwall 
(Anas strepera), Pintail (Anas acuta), Green-winged te nas carolinensis), 
Blue-winged teal (Anas discors), Baldpate (Mareca americana), Shoveller 
(Spatula clypeata), Redhead (Aythya americana), Canvasback ( a valisineria), 
Lesser scaup (Aythya affinis), and Ruddy duck (Oxvura jamaicensis). 
