It might be that in other regions where potholes are not so closely intermingled, 
areas of 1 square mile might not furnish all of the essentials, and larger units 
should be considered. The ultimate of this trend would be the breeding marsh as 
described by Hochbaum (19) in which all necessities are supplied by one unit. 
Implications of Brood Movement and Drving-up of Potholes 
Apparently there is continuous movement of broods throughout the season, This 
suggests that when a pothole near which a nest is located dries up, there is no 
reason to assume that the brood hatched from it has been lost. Further, if a pothole 
on which a brood is seen dries up, it can be safely assumed that under normal condi- 
tions the brood has managed to reach another pothole which still retains water. 
Broods can also take advantage of temporarily favorable conditions brought about in 
the more transient areas by heavy rains such as often occur during the summer, 
It is still not known whether broods raised in pothole country can leave a 
region entirely in order to reach permanent rivers or lakes in times of extreme 
drought. ‘ome data have been presented which indicate that movement might start 
early enough in the drying-up period, so that they could travel considerable distance 
using intervening waters not yet dry for resting and feeding. If that is not true, 
and they wait until the pothole on which they are located has prone dry, they would 
probably be lost, since it is the areas last to dry up that are most heavily used 
for brooding. When these go completely dry, intervening potholes could not be 
expected to contain water. 
In this respect, the system of "kee waters" described by Farrington (1915) 
might be beneficial in times of drought since broods could reach them even when 
most natural areas had dried up. 
In regions resembling the Minnedosa area, however, the effects would very 
probably be more detrimental than favorable. It would seem to be poor management 
to unbalance this desirable interspersion. of types capable of producing 50 broods 
in a normal year in order to produce 10 in times of drought, leaving conditions 
which might produce only a few more when favorable seasons again occurred. 
Surgestions for Management 
The Area Concept -~ The intent of the above discussion has been to focus 
attention on the importance of achieving a balance between the types in an area 
rather than attempting to make each pothole serve all functions, 
Improvement of the Study Area -- We have seen that the study area of 14 square 
miles contained more than enough permanent potholes to serve the needs of the broods 
vresent as was indicated by the fact that there were some concentrations well above 
the over-all average which resided together without apparent conflict. 
Nesting cover might also be considered superabundant, since there were large 
expanses of both upland cover and emergent cattail and bulrush which were not 
utilized even though they were apparently suitable for nesting. However, it should 
be pointed out, this wide distribution of over-water nesting cover may be important 
in attracting such species as canvasbacks and redhead for nesting. 
The low percent of occupancy of territorial sites during the spring suggests 
that these also were notfully utilized, but it is felt that there is not enough 
known concerning the spatial requirements of breeding pairs to justify this assum - 
tion, 
The one step in improvement of the habitat which is apparent from this study is 
that of increasing the number of available breeding territories. Plate XIX indicates 
