McWilliams, Scott [faculty advisor, Department of Natural Resources Science]
Bonasa umbellus; habitat management; vegetation analysis
Many bird species that require early successional forest are declining in the Northeast U.S. because such habitat is relatively rare and when they inhabit the more common mature forests or suburban areas they are less successful. Early successional forest is maintained by regular disturbance (wind, fire, clear-cutting, and flooding) which has been happening less frequently during the past 50 years. Bird species that have declined during this time and which inhabit early successional forest include ruffed grouse (Bonasa umbellus), blue jay (Cyanocitta cristata), chestnut-sided warbler (Dendroica pensylvanica), gray catbird (Dumetella carolinensis), field sparrow (Spizella pusilla), golden-winged warbler (Vermivora chrysoptera), eastern bluebird (Sialia sialis), common yellowthroat (Geothypis trichas), American redstart (Setophaga ruticilla), and black-throated blue warbler (Dendroica caerulescens). The goals of my project were (1) to assess whether habitat characteristics thought to be important for ruffed grouse, an important gamebird that inhabits early successional habitat, were strongly correlated with a habitat suitability index developed for grouse, and (2) to evaluate the available management alternatives for maintaining early successional forest. Ruffed grouse are a species of critical concern in Rhode Island because their populations have declined. Ruffed grouse in the central U.S. are more common because early successional habitat and aspen (Populus sp) are more available. In the Northeast, grouse tend to be found in mature mixed deciduous forests because there are few aspen dominated forests. We used a habitat suitability model to predict suitable grouse habitat in Arcadia State Forest. During summer 2006, we conducted vegetation surveys in these sites and measured the following habitat characteristics that other research had shown were important for grouse reproductive success: percent canopy cover, percent understory coverage, percent bare, overall, herbaceous, woody, grass, and slash cover, average plant heights of herbaceous and woody plants and grasses, woody stem density, basal area, coarse woody debris, and overstory and midstory composition. We detected only weak correlations between the vegetation characteristics and habitat suitability implying that either the suitability model inadequately predicted grouse habitat or the site specific vegetation data inadequately characterized grouse habitat in Arcadia State Forest. Correlations between the vegetation characteristics suggest that the mature forests in Arcadia State Forest are less suitable for grouse since they require more dense understory with high stem density and herbaceous cover. For grouse to survive in the deciduous mixed forests, habitat management must be implemented to maintain the early successional forest habitat that grouse and other bird species require. Management options include clear-cutting, prescribed burning, or silviculture. Studies throughout the country have implemented management plans that have succeeded in restoring the prime habitat for early successional species. The management plans may affect habitat of bird species occupying mature forests therefore the management techniques must be carefully implemented to ensure survival of both early successional and mature forest bird species.