Breeding bird populations of Douglas-fir/hardwood forest related to logging in northern California

Ray Judah

Graduation Date

1987

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, 1987

Committee Chair Name

Stanley Harris

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Birds--Breeding, Logging--Environmental aspects, California--Northern California Coast Range Preserve, Humboldt State University -- Theses -- Wildlife Management, Bird populations

Abstract

A breeding bird census and quantitative vegetation analysis was conducted in 1981 and 1982 on Douglas-fir/hardwood forest at the Northern California Coast Range Preserve in Mendocino County, California at sites representing an old-growth stand, a stand moderately logged in 1950 and a stand heavily logged in 1956. A select group of discriminating variables that best described the structure and floristic composition were very successful in distinguishing the three sites. The highest total volume of young hardwoods and conifers (DBH 10.2-12.6 cm) and highest volume of tanoak (DBH 27.9-91.3 cm) characterized the heavily logged site. The highest volume of madrone (DBH 12.7-27.8 cm) and greatest abundance of total hardwoods was found in the moderately logged site. The highest percentage canopy closure, large conifers (DBH91.4 cm) and volume of Douglas-fir (DBH 53.3-91.3 cm) and lowest percentage ground cover of dead and down woody material-type 1, distinguished the old-growth site. The number of bird species reported breeding for all three sites in 1981 and 1982 were 34 and 29 respectively. There was no significant difference between sites and years in the number of breeding species and individuals and the evenness and diversity indices of the breeding bird populations. There was a strong positive correlation (r=0.95) between the number of large snags (27.8 cm) and the number of territories of cavity nesters present on the three sites. The Western Flycatcher, Wilson's Warbler, and Chestnut-Backed Chickadee were the most common breeding species of the three sites and were included in a group of broad spectrum species that accounted for 47 percent of all breeding territories recorded. Breeding bird species associated with hardwoods, including the most common Black-Headed Grosbeak and Warbling Vireo, accounted for 42 percent of all breeding territories recorded. Of the four bird species associated with old-growth forest, the Spotted Owl would be considered an obligate old-growth species.

https://scholarworks.calstate.edu/concern/theses/8049g712k

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