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Virginia CZM Program: 2011 Coastal Grant Project Description and Final Summary

Project Task:VA CZM logo



William & Mary Center for Conservation Biology

Project Title:

Establishing Resource Delivery Objectives for Migration Habitat Management on the Lower Delmarva Peninsula 

Project Description as Proposed:

The lower Delmarva and Cape May peninsulas are the most significant migration bottlenecks in eastern North America, concentrating large numbers of birds within relatively small land areas.  Habitats on these peninsulas receive extremely high use by migrant landbirds during the fall months and are considered to have some of the highest conservation values on the continent.  Along the lower Delmarva Peninsula, fall migrants “fall out” in the early morning hours as they reach the mouth of the Chesapeake Bay and form a steep density gradient extending south to north within the lower 20 km.  This pattern suggests that lands near the peninsula tip have very high conservation value.  Research has documented significant levels of resource depression within this concentration area suggesting that habitat availability/quality may directly influence the condition of migrants during stopover periods and presumably their likelihood of surviving migration. 

Over the past 20 years large blocks of private land have been acquired by state and federal agencies for the purpose of restoring habitat for migratory land birds.  This activity represents a sea change in both the character and purpose of this landscape.  However, a lack of quantification of the resource requirements of the migration community has prevented the establishment of both restoration objectives and an assessment of progress to date toward such objectives.  Quantitative estimates are needed for 1) resource requirements of the collective migrant community using the peninsula, and 2) the extent to which restored habitat will contribute to these requirements.

We propose to use historic migration surveys to estimate service parameters (e.g. bird days by species, metabolic demand by species, community-wide demand, peak seasonal demand) for habitats within the lower Delmarva Peninsula. 

Federal Funding:


Project Contact:

Bryan Watts, 757.221.2247; 

Project Status:

6/1/2013 - 9/30/2013; Project Closed 

Final Product Received:

Conservation Limits and Management Opportunities for Fall Migrants along the Lower Delmarva Peninsula (PDF) 

Project Summary Provided by Grantee:

Final product completed as a report cited as :
Watts, B. D. and M. D. Wilson  2013.  Conservation limits and management opportunities for fall migrants along the lower Delmarva Peninsula.  Center for Conservation Biology Technical Report Series, CCBTR-13-05.  College of William and Mary/Virginia Commonwealth University, Williamsburg, VA.  25 pp.

The lower Delmarva Peninsula is one of the most significant migration bottlenecks in eastern North America where large numbers of birds become concentrated within a relatively small land area.  Habitats on the peninsula receive extremely high use by migrant landbirds during the fall months and are considered to have some of the highest conservation values on the continent.  Past research has documented that the lower 20 km of the peninsula tip has a significantly greater density of birds compared to other areas. 

Over the past 20 years, blocks of private land have been acquired by the state and federal agencies for the purpose of restoring habitat for migratory birds.  The conservation and management community has two distinctly different avenues available to improve habitat for fall migrant birds on the lower Delmarva Peninsula; 1) expand the amount of conservation lands through acquisition, private landowner agreements, and voluntary means, or 2) improve existing lands so they may support higher densities of birds through restoration.   

The purpose of this study was to establish a conceptual framework to place conservation progress and serve as a foundation for future efforts.  The amount of land currently supporting forest cover represents only 30.3% of the study area suggesting that there is considerable opportunity to restore additional habitat to support migrants.  Theoretically, there is space to triple the current footprint of forest habitat.  Currently, conservation lands represent less than 14% of the upland landscape and support 16% of the total forest lands.  Land that is currently ongoing restoration through conversion from unusable habitat to shrub or forest will nearly double the value of conservation lands to forest migrants and will ultimately increase the existing forest habitat within conservation lands by another 16%.  Despite its relatively small land mass, the study area is estimated to support more than 4 million bird days during the migratory period.  In order to break even energetically, these birds would require nearly 30 metric tons of food.  Conservation lands are currently supporting less than 20% of the bird use within the study.  However, if ongoing restoration projects are brought to their conservation endpoints they would more than double this contribution.
There are a number of information gaps that prevent a deeper assessment of conservation objectives for the lower Delmarva Peninsula.  At the root of this gap is the need to better understand the standing crop of energy (i.e., food) within forest patches.  Energy is the most important currency to assess whether the Lower Peninsula is an energy source for birds (i.e., birds are provided with opportunity for a net energy gain) or an energy sink (i.e., the peninsula cannot meet energetic demands).  Another information need is to gain a better understanding on the relationship between the standing crop and foraging rates of migrants.  Taken together with conservation objectives, if resource demand of migrants is higher than what reference patches can produce, then the only solution is to increase forested land base to accommodate the number of consumers.  However, this option has its limit within a confined landscape of the Lower Delmarva Peninsula.        

Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email:

A more detailed Scope of Work for this project is available. Please direct your request for a copy to

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000

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