Appalachian Region

Description

The Appalachian region stretches from the Hudson River Valley of New York to northern Alabama. Most of Pennsylvania and all of West Virginia are included in this region. Also included are the western parts of Maryland, Virginia, and North Carolina, the eastern parts of Ohio, Kentucky, and Tennessee, and the northern edge of Georgia. The eastern half of the region is characterized by mountainous ridges and valleys, while the western half is composed of plateaus and rolling hills. The northernmost hills are of glacial origin. The region is heavily forested throughout, but a little less so in southwestern Pennsylvania and eastern Ohio.

In the mountainous areas, tree species composition changes with elevation. The valleys have mixed oak-pine forests, above which are mostly oak forests. At higher elevations the composition includes birches, American beech, maples, elms, oaks, and basswood, with some eastern hemlock and white pine. Finally, spruce-fir forests and meadows can be found on the highest peaks in some areas. The local topography and soils further complicate the pattern of vegetation, thus making it difficult to generalize across the region (Bailey 1995). The western, less-mountainous areas have mixed deciduous forests with great diversity. Common species include beech, tuliptree, basswood, maples, buckeye, oaks, and hemlock.

Forest Types and Tree Species

Project Tanager study sites were almost equally distributed between deciduous forests (48% of sites) and mixed deciduous/coniferous forests (49%). The remaining 3% of the study sites were in coniferous forests. The distribution of sites with breeding Scarlet Tanagers was similar: 47% deciduous, 51% mixed deciduous/coniferous, and 2% coniferous. The most common tree species present on Project Tanager sites were maples (74% of sites), oaks (66%), American beech (22%), Eastern hemlock (21%), and pines (20%). Trees found at sites with breeding Scarlet Tanagers were similar: maples (75% of sites), oaks (71%), American beech (21%), Eastern hemlock (20%), and pines (21%).

Minimum-area Requirements

In the Appalachian region, tanagers are predicted to occur in virtually any size forest patch within landscape blocks that are at least 50% forested; that is, tanagers do not show area sensitivity in moderately or heavily forested landscapes. As the amount of forest in the surrounding landscape block decreases below 50%, the minimum area required by tanagers increases (Table 6). In this region, even small patches of roughly 25 acres located in landscapes that are only 30% forested provide moderately suitable habitat for breeding tanagers. As landscapes become highly deforested (less than 20% forest cover), however, forest patches of even low suitability are generally impossible to find because the area of forest required exceeds the amount (%) of forest available in the 2,500-acre (1,000-ha) block.

Table 6. Minimum area required to provide high, moderate, or low habitat suitability for Scarlet Tanagers based on analysis of 89 study sites in the Appalachian region (see Purpose and Use of Minimum Area Tables for definitions of habitat suitability).

Percentage of Forest
in 2,500-acre block Minimum area (acres) Required for

High Moderate Low

70 Any size Any size Any size

60 Any size Any size Any size

50 Any size Any size Any size

40 25 4 Any size

30 148 26 4

20 NA^a 185 26

10 NA NA NA

^aNot Available—acreage values exceed the amount of forest in the 2,500-acre block

Another way of assessing the suitability of a particular forest patch for tanagers is in terms of its isolation, or distance from larger tracts of contiguous forest. The suitability of small forest patches (less than 100 acres) increases if they are relatively close to larger tracts of contiguous forest (Table 7). For example, a 100-acre patch that is more than one mile from the nearest large forest is 50% less likely to support breeding tanagers than an unfragmented forest. A similar patch, however, that is within one-quarter mile of the nearest large forest is 80% as likely to have tanagers as an unfragmented forest.

Table 7. Probability of finding breeding Scarlet Tanagers in small forest patches (less than 100 acres) in relation to distance from nearest large forest in the Appalachian region.

Distance From Small Patch to Large Forest Probability of Finding Tanagers Relative to Unfragmented Forest

100 yards 1.00

1/4 mile 0.80

1/2 mile 0.64

1 mile 0.49

2 miles 0.38

5 miles 0.25

10 miles 0.19

Scarlet Tanager Associates

Eight bird species of high conservation priority are associated with Scarlet Tanagers in the Appalachian region (Table 8). Of these, only the Wood Thrush and Eastern Wood-Pewee occur at more than 50% of BBC plots with Scarlet Tanagers. Aside from the Wood Thrush, there are three national Watch List speciesWorm-eating Warbler, Cerulean Warbler, and Black-throated Blue Warblerthat occur with tanagers on at least 20% of BBC plots (Figure 11). Furthermore, in a slightly different analysis, we determined that Scarlet Tanagers were present at 61% (41 of 67 plots), 58% (29 of 50 plots), and 55% (32 of 58 plots) of BBC plots that reported Cerulean Warblers, Black-throated Blue Warblers, and Kentucky Warblers, respectively. These Watch List species are of global conservation concern and should be considered when developing habitat management plans for the Scarlet Tanager in this region.

Black-throated Blue Warbler

Figure 11. The Black-throated Blue Warbler is listed as a high-priority species in the Appalachian region by PIF and is a national Watch List species of global conservation concern. This species is area sensitive and typically occurs only in forest tracts larger than 100 ha. Black-throated Blue Warblers were present at 20% of BBC plots that also supported Scarlet Tanagers.
Photo by Bill Dyer.

Table 8. These species may also benefit from habitat improvement for Scarlet Tanagers in the Appalachian region. Species shaded with the darker color were included in the list because they occurred with Scarlet Tanagers on at least 75% of 158 Breeding Bird Census plots from 1932 to 1990. The remaining species were included because they are considered by PIF to be of high conservation priority in this region.

Species % Plots Conservation
Priority

Red-eyed Vireo 89 Low

Wood Thrush 68 High, WL^a

Eastern Wood-Pewee 54 High

Worm-eating Warbler 25 High, WL

Cerulean Warbler 22 High, WL

Black-throated Blue Warbler 20 High, WL

Kentucky Warbler 19 High, WL

Louisiana Waterthrush 15 High

Canada Warbler 11 High

^aWL—Also considered a Watch List species of global conservation concern (Carter et al. 1996)

Regional Summary

The Scarlet Tanager is considered a moderate conservation priority by PIF throughout the Appalachian region. According to the Breeding Bird Survey, this species has declined significantly during the past 30 years in parts of the Appalachian region, including the Allegheny Plateau and Blue Ridge Mountains; however, it has increased significantly in the Ridge and Valley and Cumberland Plateau areas. Because much of the Appalachian region is extensively forested, the most effective strategy for sustaining populations of Scarlet Tanagers is to prevent landscape blocks from becoming too fragmented (in other words, maintain at least 50% forest), rather than managing the size of individual forest patches. This means devising long-term management plans that consider the landscape context and future sources of fragmentation. For more information on improving habitat for Scarlet Tanagers in the Appalachian region, contact the Northeastern or Southeastern PIF Regional Coordinators. PIF contact information can be found at www.PartnersInFlight.org.