Effects on Vertebrates of Riparian Woodland Management for Control of Pierce’s

This study was initiated in cooperation with Professors Purcell and McBride to evaluate the effects on a variety of vertebrates of the removal of vegetation as well as planting of non-disease reservoir plants in riparian zones. Studies were initiated in 1997 with the establishment of eight plots, three on Conn Creek (open, managed, and not managed), and three on the Napa River (Ecological Reserve, managed, and not managed) in Napa County, and two (managed and not managed) on Maacama Creek in Sonoma County. Five sampling procedures are used per plot as follows: a.) Two “Trailmaster” bait stations once per month for 7 days, b.) 15 Sherman live traps for small mammals one night per month, c.) Three point census plots for birds once per week during the breeding season (approx. March 1 to June 15), d.) Eight nesting boxes for birds checked weekly during the breeding season and e.) Six 4-square foot reptile boards checked twice per month. Data are still too preliminary to analyze but there are some interesting trends. The bait stations showed the most common mammal to be the opossum. Larger mammal activity was highest in the Ecological Reserve and very low in the open grassy area. There was little difference between the managed and unmanaged areas. The most common mammal in the live traps was the deer mouse, Peromyscus spp. Activity was highest in the cleared area and lowest in the Reserve plot, with little difference between the managed and unmanaged areas. Over 60 species of birds were identified on the study plots during the breeding census and an extensive analysis of these results will be necessary before conclusions can be made. Six species of birds used the nest boxes and the highest occupancy rate was in the unmanaged area on the Napa River. The Reserve area had the lowest occupancy rate. Tree swallows were the only birds using boxes in the open area. The reptile boards were used by four species of lizards, two species of snakes, the Pacific tree frog, western toad, and a salamander. The most common organism was the western fence lizard. The highest use was in one of the managed areas on Conn Creek. The results to date are encouraging and with more data we should be able to say if management of riparian zones has an impact on a variety of vertebrates.