Forest Types and Tree SpeciesFifty-eight percent of Project Tanager study sites were located in deciduous forests with the remainder (42%) in mixed deciduous/coniferous forests. The distribution of sites with breeding Scarlet Tanagers was the same: 58% deciduous and 42% mixed deciduous/coniferous. The most common tree species present on Project Tanager study sites were oaks (76% of sites), maples (64%), and pines (32%). Similarly, oaks, maples, and pines were present at 79%, 67%, and 30% of sites with breeding tanagers, respectively.
Minimum-area RequirementsIn the Atlantic Coast region, tanagers are predicted to occur in virtually any size forest patch within landscape blocks that are more than 70% forested; that is, the species does not show area sensitivity in extensively forested landscapes. As the amount of forest in the surrounding landscape block decreases below 70%, the minimum area required by tanagers increases (Table 3). For example, as the amount of forest in a landscape is reduced from 50% to 40%, the minimum area required increases from 170 acres (68 ha) to 475 acres (190 ha). Note that in sparsely forested landscapes, the minimum areas required for high, moderate, or low 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.
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 4). For example, a 100-acre (40 ha) patch that is within one-half mile of the nearest large forest would be more than 70% as likely to support tanagers as an unfragmented forest. If the same patch, however, was greater than two miles from the nearest large forest, it would have less than a 40% chance of supporting tanagers when compared to an unfragmented forest.
Scarlet Tanager AssociatesEight bird species of high conservation priority are associated with Scarlet Tanagers in the Atlantic Coast region (Table 5). Of these, the Wood Thrush and Eastern Wood-Pewee are the species most likely to benefit from management for Scarlet Tanagers, as they occur at more than 60% of BBC plots that also support tanagers. Even though they are present at a lower percentage of plots, the Acadian Flycatcher, Kentucky Warbler, Louisiana Waterthrush, and Yellow-throated Vireo should also be considered when developing habitat management strategies for Scarlet Tanagers in this region (Figure 10). It's also worth noting that Scarlet Tanagers were present at 67% (4 of 6 plots) of BBC plots that reported Cerulean Warblers and 56% (10 of 18 plots) of plots that reported Worm-eating Warblers.
Regional SummaryAccording to the Breeding Bird Survey, Scarlet Tanagers have declined significantly during the past 30 years in the Mid-Atlantic Coastal Plain and Southern New England. The Scarlet Tanager is considered a moderate conservation priority by PIF in these regions. The Atlantic Coast region, like the Midwest region, is sparsely forested and heavily fragmented. Unlike the Midwest region, however, much of the fragmentation in the Atlantic Coast region is caused by development. Fragmentation caused by development, as opposed to agriculture, seems to be more detrimental to forest-dwelling birds. Furthermore, it's very difficult to establish forest corridors and restore forest habitat in extensively developed landscapes. The best strategy for sustaining populations of Scarlet Tanagers in this region is to protect existing forest through careful, long-term management that limits development in forested areas. In more rural areas, establishing forested corridors and restoring forest land might also prove beneficial. For more information on improving habitat for Scarlet Tanagers in the Atlantic Coast region, consult Bushman and Therres (1988), Hamel (1992), and Maryland Partners in Flight (1997); or contact the PIF Northeastern or Southeastern Regional Coordinators. PIF contact information can be found at www.PartnersInFlight.org.