The bird and bat deaths associated from wind turbines are more a result of the intense low pressure area created behind the blades than from the animals actually striking or rather the blades striking them. The low pressure is great enough to actually rupture the blood vessels in the lungs of the birds and bats, and that is what is killing them.
As far as using excess energy from wind turbines or other sources produced during daylight hours to pump water to a holding tank or lake, and used to run hydro turbines during times of peak demand; there is already a commercial project online now that uses that technology. Here is the link.
TVA: Raccoon Mountain Pumped-Storage Plant