within the active channel also produced a long-term negative response (de- 

 crease in numbers) from terrestrial biota. At 13 of the 25 study sites 

 gravel removal operations with these characteristics caused hydraulic 

 changes (such as permanent channel shifts, aufeis development, or increased 

 flooding) that impeded subsequent vegetative recovery of the disturbed 

 areas. However, at those sites where gravel removal created permanently 

 ponded areas, or extensive gravel and mud flat habitats with pockets of 

 ponded water or backwater areas, water birds (including waterfowl, shore- 

 birds, gulls, and terns) frequently increased utilization of the area. 



OVERBURDEN 



Overburden piles containing silts, organics, and woody slash and debris 

 facilitated rapid and continued vegetative recovery within the mined site. 

 These areas provided islands of useable passerine and small mammal habitat 

 within a relatively short-term period. At many sites overburden piles were 

 providing vegetated habitats that were being used by these species within 10 

 years after gravel removal. Ground squirrel populations frequently showed 

 immediate response to available denning habitat provided by overburden 

 piles. At most sites where piles occurred these animals were significantly 

 more abundant within the mined site than in adjacent floodplain reaches. 



When this overburden material was broadcast over the ground in areas 

 where it would not be washed downstream it was equally effective in facil- 

 itating rapid vegetative recovery and development. 



PERMANENTLY PONDED HABITATS 



At eight sites the gravel removal operation (primarily through pit exca- 

 vation) created permanently ponded habitats. Although this operation led to 

 a long-term change from natural terrestrial conditions, at several sites 

 this mining result led to the development of a diverse habitat that provided 

 high quality feeding, nesting, and cover areas for passerines, small mam- 

 mals, water birds, and furbearers. Factors that were found to influence the 

 fauna response to these areas were: shoreline configuration, shoreline 

 vegetative cover, water depth profiles, presence of islands, pit size. 



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