USGS Science⌕ Search
Home/Archive/USGS

USGS · 70176687

Grassland and shrubland birds of Gettysburg National Military Park and Eisenhower National Historic Site: Current status and management recommendations

Bruce G. Peterjohn
View original source ↗Read source document ↗Export metadata ↓

Abstract

Gettysburg National Military Park (NMP) and Eisenhower National Historic Site (NHS) were surveyed for grassland birds during the 2005 breeding season. These parks currently maintain a total of approximately 1,220 ha (3,015 ac) of grassland habitats within a mosaic of cultivated fields and woodlands. The grasslands are hayfields managed through agricultural leases and fields maintained by the National Park Service (NPS). Most grasslands are composed of introduced cool-season grasses, but Gettysburg NMP maintains a few fields dominated by switchgrass (Panicum virgatum) and is creating additional warm-season grasslands. Hayfields managed through agricultural leases support few grassland birds. The most numerous grassland bird communities are found between Seminary and Cemetery ridges in fields managed by the NPS. The parks discourage hay harvesting before July in all fields in an effort to improve the reproductive success of grassland birds. Shrub-dominated habitats were scarce in both parks. A few areas that were harvested recently for timber supported early successional communities in Gettysburg NMP. Other shrublands were limited to narrow corridors (<10 m [32 ft]) bordering fields and drainages. No shrublands were present on Eisenhower NHS, but an abandoned pasture along Willoughby Run was reverting into a mesic shrubland. Four species of obligate grassland birds were recorded during the 2005 surveys. A population of approximately 130 bobolinks (Dolichonyx oryzivorus) was primarily restricted to grasslands between Seminary and Cemetery ridges maintained by the NPS and a hayfield on Eisenhower NHS. This population is large for southeastern Pennsylvania and the surrounding region. Eastern meadowlarks (Sturnella magna) were most numerous in the same fields occupied by bobolinks but smaller numbers were scattered in other grasslands. Grasshopper sparrows (Ammodramus savannarum) were locally distributed in Conservation Reserve Program fields and other grasslands with more open vegetation. Savannah sparrows (Passervulus sandwichensis) were limited to one disturbed area undergoing conversion to warm-season grasses. When compared with other cultural parks in this region, the Gettysburg-Eisenhower complex supports a relatively abundant grassland bird community. This community is restricted to a portion of existing grassland habitats, but the potential exists to support a more diverse and abundant grassland avifauna. The following recommendations provide the most immediate benefits for breeding grassland birds in these parks under the current habitat conditions and management strategies. These recommendations are based on the assumption that the current policy of delayed mowing continues in both parks: improve grassland composition on leased hayfields; increase extent of early successional stages of grasslands; reduce fragmentation of grassland habitats; and improve grassland diversity by creating additional communities of native warm-season grasses. Because shrublands are currently scarce in both parks, the only recommendation is directed towards creating and maintaining shrub-dominated successional habitats: Explore opportunities for creating shrubby successional habitats in both parks.

Explore related subjects

Technical ReportReport

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Bruce G. Peterjohn. 2007. Grassland and shrubland birds of Gettysburg National Military Park and Eisenhower National Historic Site: Current status and management recommendations. https://pubs.usgs.gov/publication/70176687

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

Cyanobacteria Assessment Network: Pilot study with Sentinel-2 derived chlorophyll data

Harmful algal blooms (HABs) affect global water quality, limiting uses like recreation and consumption because of excessive algal biomass and toxin production. These blooms cause surface scums, taste and odor issues, hypoxia, and negative health and socioeconomic impacts. The US Army Corps of Engineers (USACE) manages over 400 lakes and reservoirs and seeks to improve monitoring of HABs through Sentinel-2 (S2) satellite imagery. The purpose of this project is to develop workflows for a national chlorophyll-a product with 20 m spatial resolution, enabling HAB monitoring for over 270,000 lakes and reservoirs. The 1-year pilot study established a federal partnership to conduct preliminary S2 processing steps, using datasets from Florida, Ohio, and Oregon. Key steps included in situ data aggregation, data assimilation, S2 algorithm evaluation, spatial and temporal compositing, satellite sensor cross-validation, and web hosting of an example prototype product. The study covers 29 USACE reservoirs, with cross-validation using Sentinel-3 (S3) data from 212 lakes. The multiagency initiative aligns with federal agency missions to protect health and the environment, supports acts like the 2017 Harmful Algal Bloom and Hypoxia Research and Control Act, and has annual potential avoided costs of $42 million.

contiguous United States↗
USGS2026

Field evaluation of the Automated Barge Clearing Deterrent (ABCD): Hydrodynamic, navigation, and fish response effects

The escape and subsequent spread of invasive carp (notably, bighead carp [ Hypophthalmichthys nobilis ] and silver carp [ H. molitrix ]) from aquaculture ponds and sewage lagoons into the Mississippi and Illinois Rivers poses a significant risk to further spread of these fish into the Great Lakes. Prior research demonstrated that commercial tows can transport juvenile invasive carp through locks and other barriers to fish migration. A recent physical model study recommended a linear array of bubble diffusers, the Automated Barge Clearing Deterrent (ABCD), for further evaluation in mitigating the transport of small fish in commercial tows. The present field study evaluated the ABCD for navigation safety and barge junction flushing capacity. An instrumented commercial tow executed 119 lock approaches with the ABCD both operating and idle. Pilot interviews and tow trajectory analysis indicated no significant navigation safety issues. The measured velocity data, fish recapture data, and a simple fish displacement model indicated that the ABCD produced sufficient flow to expel all passive objects and many small juvenile invasive carp. However, the ABCD is less likely to expel large juvenile invasive carp due to their stronger swimming ability. The ABCD and two alternative configurations prove strong contenders for further development and application.

Illinois↗
USGS2026

The conifer-carbon connection in sagebrush steppe

How could more trees be “bad” for carbon? Conifers are expanding into the shrub-dominated sagebrush steppe across much of the Western U.S.A., which increases carbon storage both aboveground and belowground (in soils and roots) – but the long-term impacts of conifer expansion are complex. Short-term increases in carbon storage from increased tree cover can be lost to wildfire. Conifer expansion increases woody fuel loads, making large, severe wildfires more likely. High plant mortality after severe fire, even in relatively fire-resilient perennial grasses, increases the risk of annual grass conversion and subsequent losses of up to 50% of ecosystem carbon, including soil carbon. Preventing conifer expansion through early intervention can protect the large belowground carbon stores of healthy sagebrush steppe.

Technical Report↗