Protecting Forest Bird Habitats in a Changing Climate

Yes
Planning

Audubon Vermont is looking at how to improve forest bird habitat in a way that also enhances the ability of forests to adapt to climate change.

Audubon Vermont and the Vermont Department of Forests, Parks, and Recreation developed the innovative Foresters for the Birds project, which works to maintain working forests and bird habitat by integrating the practices of timber and songbird habitat management.  More recently, Audubon Vermont has been looking at its how its efforts to promote Silviculture with Birds in Mind can also help adapt forests to changing conditions.

Climate Change and Forest Birds

Vermont and the Atlantic Northern Forest region is considered North America’s nursery for neo-tropical migratory birds; in fact this region has some of the highest diversity of breeding birds in the United States. However, a number of studies project changes to both bird populations and forests due to climate change. The National Audubon Society’s Birds and Climate Change Report predicts that roughly half of Vermont’s birds will see their ranges shift or contract by 50% or more. Climate Change Bird Atlas results also indicate that climate change will alter breeding habitat conditions for priority bird species in Vermont and regionally. Some more specific impacts on forest birds include:

  • Increased winter minimum temperatures and decreased probability of lower lethal temperatures may lead to range expansion and abundance of non-native insect pests such as hemlock wooly adelgid, resulting in decreases in native tree species diversity and subsequently bird species diversity.
  • Increases in non-native invasive plant species will likely decrease abundance of the critical insect food resource for birds during the nesting season, decrease nesting success due to increased predation, and increase abundance of lower quality fruit resources that are important to increased bird fitness prior to migration.
  • Increased frequency and intensity of extreme weather events will result in larger and more frequent natural disturbances affecting the forest. As a result young, early-successional forest habitats may become more abundant on the landscape, further promoting the spread of non-native invasive plants and decreasing habitat structure for songbirds nesting in mature forests.
  • Reduced habitat suitability for many common tree species is likely to result in changes to the bird species community, their nesting success, and overall incidence of birds that are currently characteristic of the region. 

Despite the potential impacts and challenges to forests and forest nesting birds as a result of climate change, there is a significant opportunity for bird conservation in Vermont and regionally. Northern New England is at the core breeding range many bird species. For example, the black-throated blue warbler has nearly one-third of its global breeding population in the region. Although climate change models show decreasing habitat in the southern part of its breeding range, the Northeast is likely to continue to provide suitable habitat, increasing the region’s importance to the global conservation of many bird species.

veery nest in forest

Veery nest (courtesy Steve Hagenbuch, Audubon Vermont)

Adaptation Actions

Audubon Vermont hopes to use two demonstration locations (the Cold Hollow Woodlots and one additional location) to implement practices drawn from Audubon Vermont’s Silviculture with Birds in Mind in a way that not only improves breeding bird habitat but also address expected climate change impacts.  These demonstration locations are representative of common forest conditions in Vermont and regionally, in that past management has resulted in forests that are largely young (50-80 years old), even-aged and provide poor habitat conditions for birds and other forest species. Throughout Vermont, these forest conditions on small parcels usually means that pre-commercial timber improvement treatments do not happen due to the costs involved; leaving large swathes of Vermont’s forest vulnerable.

The proposed demonstration would utilize non-commercial treatments that will have an immediate effect of improving the overall resilience of the forest (i.e., the ability of the system to maintain its ecological state given increased disturbance and change) to changing conditions, while simultaneously beginning a longer-term transition toward future-adapted forests.  These silvicultural treatments would create distinctly different stand structures and shift species composition toward species that will fare better under future conditions, while serving important habitat functions. Additionally, tree planting is a rare practice in Vermont’s forests but the project would plant red oak saplings to facilitate the movement of this more southern, native species which is likely to become more common under a new climate regime.  The integration of multiple forest landowners in cross-boundary management also allows for facilitating change at the landscape-level.

Project Outcomes

These silvicultural treatments are aimed at enhancing species diversity and structure to affect the following near term (0-15 year) habitat and timber quality as well as and long-term (50+ year) adaptation:

  1. Maintain or improve the ability of forest to resist pests and pathogens be retaining and releasing the most vigorous trees, and developing a more complex structural and species diversity. Research has shown that maintaining biodiversity buffers against pests and pathogens. Diversity of structure and enhanced vigor also enables the forest to resist and respond to disturbances by pests and pathogens.
  2. Prevent the establishment of invasive plants with pretreatment removal and post treatment monitoring.
  3. Manage herbivory by keeping tops unlopped and retaining coarse woody material
  4. Protect forest from severe disturbance and prepare for these disturbances by enhancing residual vigor and growth using crop tree release and promoting regeneration throughout the treatment area.
  5. Maintain and enhance species and structural diversity by implementing a variety of silvicultural treatments across the harvest area; promoting age and structural diversity; and retaining biological legacies such as large trees, hard and soft mast, cavities and snags, and variable densities.diversity and structural diversity; and retaining biological legacies such as large trees, hard and soft mast, cavities and snags, and variable densities.

Wood thrush (courtesy Brian E. Small/VIREO)

Wood thrush (courtesy Brian E. Small/VIREO)

Last updated: May 12, 2015