Bat use of remnant old-growth redwood stands

Most of the old-growth redwood (Sequoia sempervirens) in California has bee n cut; regenerating forests will probably never resemble those that were ha rvested and what old growth remains on private land occurs in small, isolat ed remnant patches. The landscapes in which these stands occur differ so ma rkedly from their original condition that their value as habitat to many sp ecies of wildlife, including bats is unknown. Previous research in unfragme nted redwood forests demonstrated that bats use basal hollows in old growth redwoods as roosts We sought to determine whether bats use similar old-gro wth trees as roosts when they occur in small, remnant patches of isolated o ld growth on commercial forest land. We compared bat occurrence in remnant and contiguous stands by collecting guano in traps suspended in hollows and by monitoring flight activity with ultrasonic bat detectors. Hollows in tr ees within the remnant stands had significantly more guano deposited per tr ee than the trees within the contiguous forest. the mean numbers of bat pas ses per night were statistically indistinguishable between the two treatmen ts, although mean flight activity in the remnant stands was greater than in the contiguous forest. Bats frequently used basal hollows in small (<5 ha) stands of remnant old growth, which may be due to the closer proximity of remnants to stream courses, to their greater interface with edge where fora ging success may be greater, or to the fact that the lower density of hollo w-bearing trees in remnants than in contiguous forest favored greater use p er tree. Significant use of small, residual old-growth redwood provides rea son to maintain these remnants in managed landscapes as potentially importa nt habitat for forest bats.