WESTERN TOAD (ANAXYRUS BOREAS) BREEDING TIMING AND LARVAL DEVELOPMENT IN LAKE CUSHMAN RESERVOIR, WASHINGTON STATE

Abstract

We observed Western Toad (Anaxyrus boreas) breeding from mid-May to late June, coincident with a reservoir rise of ≤1.2 m in Lake Cushman, Washington State. Breeding occurred at 5 sequentially inundated sites and included diverse habitats. Early-spawned clutch-strings remained attached to the lake bottom but became vertically suspended during the lake-level rise. Embryos and hatchlings nearest the bottom were in cooler water than those near the top. Development through hatchling stages took up to 40 d for early spawn. Locations of later spawning were shallower and warmer, and larval development progressed rapidly. Ultimately, the extended spawning season and varied sites and habitats may provide reproductive success resilience. Reservoir water-level management during Western Toad breeding and larval development may effect: (1) breeding habitat availability; (2) larval development rates; and (3) reproductive success.