Lindsay Wildlife Experience staffers could be excused for having the kind of daydreams lottery winners indulge in: The 60-year-old wildlife-rehabilitation center has received a $2.6 million gift from the late Stephen S. Ball, its largest-ever single donation. The money could be used to upgrade wildlife rescue and rehabilitation facilities, including the hospital’s treatment rooms and animal housing; for new aviaries and outdoor improvements of animal exercise areas; or to help build an endowment fund, according to a Lindsay news release Friday.