MORTON, Martin L.*; PEREYRA, Maria E.; University of Tulsa; University of Tulsa: Sexual differences in habitat useage by Yosemite Toads

While surveying habitat occupied by Yosemite toads (Bufo canorus) at Tioga Pass in the Sierra Nevada of California during their post-breeding period, we discovered sexual differences in distribution of adults. Wet meadow bottoms, near breeding pools, were occupied by the majority of toads (immatures and adults combined = 58 %), but the distribution of adults with regard to habitat features was asymmetric. Of 237 adult females located, 108 (45.6 %) lived at the highest part of the meadow environment where it contacted talus slopes, but only 7 of 225 males (3.1 %) inhabited that area. We suggest that higher, drier locations, even though they may be many hundreds of meters from breeding pools, are preferred for feeding and hibernation by females and that this preference may reflect their irregular participation in reproduction; annual breeding attempts were typical of males, but females usually oviposited only at two- to four-year intervals. Apparently, environmental factors at high altitude, such as low temperatures and short growing seasons, deter females from producing a clutch during every breeding season. Relatively long inter-breeding intervals and greater dispersal may be a general characteristic of female amphibians occupying montane environments and this should be accounted for in plans for their conservation and management.