Improving Habitat for Scarlet Tanagers

Specific Habitat-area Requirements for Scarlet Tanagers

The following sections provide specific information about the habitat requirements of Scarlet Tanagers in four geographic regions. These guidelines are based directly on the results of Project Tanager and focus on the effects of forest fragmentation. They tell us the minimum area required to provide the most suitable habitat for breeding tanagers, as well as the chances of attracting tanagers to less-suitable habitats. For information on improving other aspects of habitat suitability, such as forest structure and age, see the "General Forest Management Guidelines" and the suggested readings referenced in the regional summaries of this publication.

Results from Project Tanager confirm that breeding Scarlet Tanagers respond negatively to forest fragmentation; that is, tanagers are much less likely to attempt breeding in small or isolated forest patches, especially in landscapes already largely deforested by development or agriculture. The degree to which Scarlet Tanagers are affected by forest fragmentation (their area sensitivity) differs geographically within their range (see Rosenberg et al. 1999). Therefore, we divided the tanager's range into four regions, the Midwest, Atlantic Coastal Plain, Appalachian, and Northern Forest to assess more accurately the effects of forest fragmentation and provide guidelines that are accurate within various portions of the range.

In each regional profile we provide information designed to help land managers evaluate and improve habitat for Scarlet Tanagers in their region. Each regional profile includes

a map and description of available forest types
Project Tanager results of forest types used by Scarlet Tanagers
estimates of the minimum habitat area required to support breeding Scarlet Tanagers
a list of associated forest birds that may also benefit from habitat improvement for Scarlet Tanagers
a regional summary that briefly presents the most important management strategies for that region

Within each region, the likelihood that a forest patch of a given size will attract tanagers varies based on the amount of forest remaining in the surrounding landscape and how close the forest patch is to the nearest large forest (more than 100 acres). For example, a 20-acre (8-ha) woodlot may be unlikely to support tanagers if it is surrounded by agricultural land, but a similar woodlot that is close to a large, extensively forested state park may be almost as likely to have tanagers as the park itself.

Because the probability of finding tanagers in a forest patch of a given size depends on the proportion of forest in the surrounding landscape, we offer a range of minimum-area estimates for landscapes with different proportions of forest. For this purpose, we define a landscape as a 2,500-acre (1,000-ha) block surrounding each forest patch. If a landscape block surrounding a 50-acre forest patch is mostly forested (say, 70%), then it may be much more likely to support tanagers than the same sized patch in a landscape block that is only 20% forested. Where appropriate, we also give a range of minimum areas that might be affected by the degree of isolation, or distance to the nearest large forest (more than 100 acres). Finally, because in many areas remaining forest patches may not reach our calculated minimum-area requirements, we provide a range of patch sizes that do have significant—even if lower—chances of attracting tanagers.