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CONCEPTUAL ECOLOGICAL MODEL FOR MANAGEMENT OF BREEDING GRASSLAND
BIRDS IN THE MID-ATLANTIC REGION
Natural Resources Report NPS/NER/NRR--2006/005
Bruce Peterjohn
USGS Patuxent Wildlife Research Center
Laurel, MD 20708
bpeterjohn@usgs.gov
May 2006
U.S. Department of the Interior
National Park Service
Northeast Region
Philadelphia, Pennsylvania
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Introduction
The status of
grassland birds has become an increasingly important conservation issue.
These species exhibit the most consistent population declines of any
group of North American birds during the past 40 years. Anecdotal evidence
suggests these declines have been occurring for nearly a century (Peterjohn
and Sauer 1999). While the widespread conversion of grasslands into
other habitats contributed to these declining populations, other factors
such as habitat fragmentation and mowing regimes are also implicated
(Vickery et al. 1999a). This plight of grassland birds has heightened
awareness of the need for concerted conservation actions to reverse
these seriously declining population trends.
The National Park Service (NPS) is positioned to potentially contribute
to grassland bird conservation in the Mid-Atlantic Region. The NPS maintains
a number of historic sites and former battlefields that are managed
for their cultural significance but also support wildlife populations.
Many of these “cultural parks” maintain open landscapes to
recreate land use patterns that existed at the times of the historical
events. These open landscapes are primarily managed grasslands which
could be maintained to benefit grassland birds.
In 2005, the NPS initiated a project exploring the potential of “cultural
parks” to support significant breeding grassland bird communities.
This project involved parks within three NPS Inventory and Monitoring
Program (I&M) networks, Mid-Atlantic, National Capital, and Eastern
Rivers and Mountains. Five parks were selected for the initial focus
of this study, all of which maintain open landscapes for interpretation
of historic events. Most parks were selected because they represent
the most extensive grassland habitats within their networks, with the
rationale that if these parks cannot support significant breeding grassland
bird communities, then parks with smaller acreages cannot support these
communities either. The five parks included in this study are: Antietam
National Battlefield, Fort Necessity National Battlefield, Gettysburg
National Battlefield, Manassas National Battlefield, and Monocacy National
Battlefield.
This conceptual
ecological model is one product of this project. The information presented
below allows NPS Network Coordinators to understand the factors to consider
when making decisions concerning grassland management within their networks.
This model provides park Resource Managers with information on grassland
ecology in the Mid-Atlantic Region, the ecological requirements of grassland
birds likely to occur in their parks, and management issues that influence
whether significant breeding populations can be expected to occupy grasslands
created and maintained in the parks. The Resource Managers can then
make informed decisions concerning their ability to create and maintain
grassland habitats.
The emphasis of this conceptual model is restricted to management of
breeding grassland birds. Additional species may occur in this region
during migration and winter, while habitat requirements of all grassland
birds during nonbreeding seasons will differ from those described for
the breeding season.
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