greater in 1977 than those indicated by this study, although the two studies 

 are not strictly comparable due to differing methods and objectives. 



Large water birds other than waterfowl which used stockponds within the 

 mine study area are indicated in table 30. Groups of up to 25 double-crested 

 cormorants were seen repeatedly on NC09 in April, May, and June. These pro- 

 bably represent feeding flights from large nesting colonies in Big Dry Arm 

 or possibly non-breeding summer visitors. 



Overwintering of waterfowl was not observed in and near the mine study 

 area, as stockponds and most streams freeze over in winter (tables 27 and 29). 

 Fort Peck Reservoir also freezes over completely during most winters, but serves 

 as an important fall staging area for large numbers of grebes, double-crested 

 cormorants, and waterfowl (Shupe, p.c). Large wintering populations of water- 

 fowl concentrate on ice-free stretches of the Missouri River, especially just 

 below Fort Peck Dam (Appendix J). 



Climatic Factors Influencing Waterfowl Use . Waterfowl habitats and pop- 

 ulations of the northern Great Plains are characterized by wide fluctuation, 

 due to wide annual variations in climatic conditions. Thus, one seldom en- 

 counters a year having conditions which could be termed normal or typical. The 

 relatively low waterfowl breeding populations encountered during this study 

 should not be interpreted to represent the typical or average situation, as 

 weather conditions during 1977 were unusually dry and otherwise suboptimal for 

 waterfowl. Winter snowfall and spring rain were exceptionally low, and by mid- 

 June most streams and stockponds contained little water and many were completely 

 dry. The major rainstorm of June 14 and 15, 1977, filled most stockponds to 

 capacity overnight, but by that time many potential breeders -- especially such 

 early nesters as pintails -- had left the area, and the optimum breeding season 

 for most species had passed. Therefore, the results presented here are by no 

 means typical, and waterfowl use and production will likely be much higher during 

 years having more suitable weather and moisture conditions. A primary goal of 

 the proposed monitoring program presented later in this report is to determine 

 waterfowl use and density on the mine study area during typical and optimum 

 years. 



During normal to wet springs, roadside ditches and dugouts probably pro- 

 vide additional nesting and feeding habitat for waterfowl, but such habitat 

 was largely absent in 1977. This is indicated by the fact that up to four 

 species of waterfowl and/or coots were seen on all runs of the Circle roadside 

 survey route prior to 1976, but none were seen in June of 1977 (Appendix E). 



Stockpond Characteristics . Several studies have shown that breeding sea- 

 son waterfowl use generally increases with reservoir size, reservoir age, and 

 with the amount of tall grass and shrubbery along the shoreline (Berg 1956, 

 Gjersing 1971, Lokemoen 1973, Smith 1953). This was observed to be the case 

 within the mine study area, where waterfowl use was highest along Nelson Creek 

 and its tributaries wnore bordered by bulrush marshes or silver sagebrush flats, 

 and along the larger, older stockponds which are bordered by marshes or shrub- 

 bery. Most smaller stockponds in the mine study area are bordered by bare 

 earth or heavily grazed and trampled grassland, and thus lack nesting cover 

 necessary for most waterfowl species (table 3). Emergent vegetation was lacking 

 or scarce even in the largest stockponds, which accounts in part for low breeding 



147 



