Masters Theses

Date of Award

8-1999

Degree Type

Thesis

Degree Name

Master of Science

Major

Wildlife and Fisheries Science

Major Professor

David Buehler

Committee Members

Ralph Dimmick, Arnold Saxton

Abstract

The U. S. Forest Service is required under the National Forest Management Act of 1976 to consider how their management activities will sustain wildlife populations. Decreases in timber harvest and changes in the regeneration systems of Cherokee National Forest will change the availability of habitat of songbirds. I used a computer simulation of the forest to model the effects of these changes upon habitat availability for six songbird species: Acadian flycatcher (Epidonax virescens), blue-headed vireo (Vireo solitarius), chestnut-sided warbler (Dendroica Pensylvanica), tufted titmouse (Parus bicolor), yellow-billed cuckoo (Coccyzus americanus), and yellow-throated warbler (Dendroica dominica). The SAS-based forest simulation model included elements of natural disturbance and variable harvest intensities. Disturbance regimes were based upon a combination of published studies, historical records in our study area, and expert opinion. The forest simulation model created a stand inventory for the Tellico, Hiwassee, and Ocoee districts of Cherokee National Forest at ten year intervals. Bird habitat models were applied to these stand inventories to quantify changes in habitat across four forest simulations of varying harvest intensity between 1993 and 2053: nocut, expected harvests (based upon expert opinion), twice the expected harvest intensity, and three times the expected harvest intensity.

Late succession species showed substantial increases in habitat availability from 1993 to 2053. Acadian flycatcher and yellow-throated warbler habitat increased by 164 and 119%, respectively, at expected harvest levels. Blue-headed vireo and tufted titmouse habitat increased by 31 and 1.3 %, respectively, at expected harvest levels. Changes in habitat availability for these four species were inversely related to harvest intensity, however only tufted titmouse showed a decline in habitat availability at the highest harvest intensity. Based upon known breeding densities, none of these species' populations dipped below a minimum population of 250 breeding pairs. Chestnut-sided warbler remained relatively constant at expected harvest levels, but declined at lower harvest intensities. Yellow-billed cuckoo habitat declined by 21 % at expected harvest levels. Habitat for these species was directly related to the harvest intensity. Neither of these species' populations are expected to decrease below estimated minimum viable population levels (250 pairs).

Changes in timber harvest regimes may affect more disturbance-dependent species, like the golden-winged warbler. Golden-winged warbler populations have shown significant declines in many regions eliciting concern among conservationists. We measured productivity and characterized the territory and nesting habitat characteristics of golden-winged warblers in regeneration areas in the Nantahala National Forest, North Carolina, and Cherokee National Forest, Tennessee, in 1997 and 1998. Golden-winged warblers occupied young stands with low basal area (P = 0.0310), and better roads (P = 0.0332), and nested in sites with high herbaceous density (P = 0.0114). Nest sites had fewer saplings (P = 0.0228) and lower canopy cover (0.0327) than the surrounding territory. Overall nest success was 72.5 %. Nests fledged an average of 3.65 young. Recently harvested stands (age ≤ 13 years) provided habitat for golden-winged warblers capable of supporting reproduction at levels equal to or greater than other study sites across the range of this species.

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