Midwest Region

Description

The Midwest region is defined as the portion of the Scarlet Tanager's range that is west of the Appalachian Mountains and south of the Great Lakes. It stretches from the southern shore of Lake Ontario in the east, across the southern parts of Ontario, Michigan, and Wisconsin, into southern Minnesota. The region extends south to include the northern edge of Alabama in the east, and to the northeast corner of Oklahoma in the west. The western and southern boundaries of this region are defined by the limits of the Scarlet Tanager's range.

Relatively small forest patches located within a largely agricultural landscape characterize much of the region. More heavily forested areas are located in central Tennessee, southeastern Missouri, and western Arkansas. Because the region has less precipitation than areas to the east, the broadleaf deciduous forests of the Midwest tend to include more of the drought-tolerant oak-hickory association (Bailey 1995). Forests in the northern and eastern parts of the Midwest region contain more maples, American beech, and basswood, whereas the western part becomes savanna-like as it gradually gives way to prairie. Oaks and hickories dominate upland forests in the prairie region, whereas farther west, floodplain forests contain cottonwood, willows, and elms (Bailey 1995). The more mountainous areas of Arkansas support oak-hickory forests that include coniferous trees, especially pines.

Forest Types and Tree Species

Eighty-six percent of Project Tanager study sites were located in deciduous forest and 14% occurred in mixed deciduous/coniferous forests. Scarlet Tanagers did not show any preference between these two forest types. The most common tree species present on tanager-occupied sites in the Midwest were oaks (80% of sites), maples (58%), and hickories (35%).

Minimum-area Requirements

In the Midwest region, tanagers are predicted to occur in virtually any size forest patch within landscape blocks that are more than 70% forested; that is, the birds do not show area sensitivity in extensively forested landscapes. In a block that is 70% forested, roughly 66 acres (26 ha) are required to achieve High Suitability (Table 1). As the amount of forest in the surrounding block decreases, the minimum area required by tanagers increases sharply, roughly doubling for every 10% reduction in surrounding forest. Note that in sparsely forested landscapes, the minimum areas required for high and moderate suitability are sometimes impossible to achieve because the area of forest required exceeds the amount (%) of forest available in the 2,500-acre (1,000-ha) block.

Table 1. Minimum area required to provide high, moderate, or low habitat suitability for Scarlet Tanagers based on analysis of 298 study sites in the Midwest 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 66 11 1

60 141 23 3

50 292 47 6

40 605 97 12

30 NA^a 208 27

20 NA 481 62

10 NA NA 173

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

Scarlet Tanager Associates

Twelve bird species of high conservation priority are associated with Scarlet Tanagers in the Midwest region. Most notably, the Eastern Wood-Pewee and Wood Thrush were found at more than 90% of BBC plots that also contained tanagers (Figure 9). There were seven high-priority species that occurred with tanagers at more than 25% of BBC plots (Table 2). In addition, we found that Scarlet Tanagers were present at 35% (9 of 26 plots) of BBC plots that reported Cerulean Warblers and 86% (6 of 7 plots) of plots that reported Worm-eating Warblers. These data suggest that appropriate management actions for Scarlet Tanagers will certainly enhance populations of Eastern Wood-Pewees and Wood Thrushes and are likely to improve habitat for these other high-priority forest birds as well.

Figure 9. The Eastern Wood-Pewee is listed as a high-priority species in the Midwest region by PIF. Although still common in most areas, Breeding Bird Survey data suggest that this species declined by 36% from 1966 to 1993 (Price et al. 1995). Eastern Wood-Pewees were present at 91% of BBC plots that also supported Scarlet Tanagers.
Photo by Mike Hopiak.

Table 2. These species may also benefit from habitat improvement for Scarlet Tanagers in the Midwest region. Species shaded with the darker color were included in the list because they occurred with Scarlet Tanagers on at least 75% of 34 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

Eastern Wood-Pewee 91 High

Wood Thrush 91 High, WL^a

Red-eyed Vireo 82 Low

Blue Jay 82 Low

Northern Cardinal 82 Low

Downy Woodpecker 79 Low

Great Crested Flycatcher 76 High

Acadian Flycatcher 41 High

Yellow-billed Cuckoo 35 High

Red-headed Woodpecker 29 High, WL

Kentucky Warbler 26 High, WL

Cerulean Warbler 23 High, WL

Louisiana Waterthrush 18 High

Worm-eating Warbler 15 High, WL

Whip-poor-will 12 High

Hooded Warbler 12 High

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

Regional Summary

The Scarlet Tanager is not considered a high conservation priority by PIF in the Midwest region. According to the Breeding Bird Survey, Scarlet Tanager populations in that region have remained stable during the past 30 years. With the exception of a few heavily forested areas (see "Description" section above), the Midwest region is sparsely forested and the remaining forest is heavily fragmented. As a consequence, the best strategies to sustain populations of Scarlet Tanagers are to protect existing forests and promote the establishment of forested corridors to reconnect isolated forest patches. In addition, when appropriate, large areas of forest could be reestablished via the reclamation of abandoned farms, surface mines, and landfills. For more information on improving habitat for Scarlet Tanagers in the Midwest region, consult Herkert et al. 1993 and Hamel 1992; or contact the PIF Midwest Regional Coordinator. PIF contact information can be found at www.PartnersInFlight.org.