Baseline Surveys for the Arroyo Toad (Bufo californicus) in the Sweetwater River Channel, San Diego County, California.

Type: report

Article abstract: In 2002 The U. S. Geological Survey (USGS) was contracted by the Sweetwater Authority to conduct a study examining the short-term and long-term effects of Loveland Dam operations on the arroyo toad (Bufo californicus) below that dam in the Sweetwater River channel. The first phase of the study was a risk assessment, which examined the short-term and long-term effects of Loveland Dam operations on arroyo toad reproductive success and population viability (see Madden-Smith et al. 2004). This report covers the second phase of the study, which involved baseline surveys for arroyo toad habitat and arroyo toads below Loveland Dam. During the 2003 arroyo toad breeding season, daytime habitat and nocturnal presence surveys for arroyo toads were conducted at four sites along the Sweetwater River: 1) Sycuan Peak Ecological Reserve, Sweetwater River; 2) San Diego National Wildlife Refuge, Sweetwater River; 3) Cottonwood Golf Course along the San Diego National Wildlife Refuge border, and 4) upper Sweetwater Reservoir. Habitat assessment included: percent vegetative cover, streambed and bank vegetation type, substrate type, descriptions of arroyo toad habitat characteristics and hydrologic descriptions including stream width and estimates of flow. Habitat assessment at Sycaun Peak Ecological Reserve resulted in two reaches rated as high quality, two reaches rated as good quality, three reaches rated as marginal quality and two reaches rated as poor quality. Habitat assessment at San Diego National Wildlife Refuge and upper Sweetwater Reservoir resulted in one reach of high quality habitat for each site. Habitat assessment at Cottonwood Golf Course resulted in one reach of good quality habitat. Based on the results of the daytime habitat assessment, nocturnal adult presence surveys were conducted at potentially suitable arroyo toad habitat (habitat rated high or good quality). Nocturnal surveys were conducted for six nights at each site and arroyo toads were not detected at any of the sites. Survey techniques were in accordance with the recommended U. S. Fish and Wildlife Service (USFWS) Protocol (USFWS1999b). For inaccessible areas, available arroyo toad abundance and distribution data were used to fill in where current information is lacking. Management concerns (e.g., presence of bullfrogs or other non-native predators, obstructive vegetative growth [native and non-native], etc.) were also identified as part of the baseline surveys. Results

Number of pages: 70

Authors: Madden-Smith, Melanie; Ervin, Edward; Fisher, Robert N.;

Day: 5

Month: October

Year: 2005

Prepared for: Sweetwater Authority;

Prepared by: U.S. Geological Survey, Western Ecological Research Center;

Keywords: arroyo toad; baseline; habitat assessment; Loveland Dam; risk assessment; San Diego National Wildlife Refuge; Sweetwater;

Species: Arroyo toad