Valley Forge’s birds in 2019: volunteers, field sparrows and forest health

Volunteers walked Valley Forge National Historical Park in the summer of 2019 listening for birds, and the National Park Service's Mid-Atlantic Network turned their counts into a short status brief. Among its findings, field sparrows, a species of regional conservation concern, were the third most common bird in the park's grasslands.

What the survey did

For ten years, Mid-Atlantic Network scientists have worked with skilled local volunteers to monitor breeding birds in national parks across the mid-Atlantic. In summer 2019 ten volunteers made 233 surveys at 78 sites across the park. In each survey they noted every bird heard or seen over ten minutes, and forest and grassland sites were visited several times during the breeding season.

The park has been working to increase its acreage of native warm-season grasses to benefit birds. The 2019 results show that some grassland birds, such as field sparrows, are relatively abundant.

Species of regional concern

Partners in Flight, a network of organizations involved in bird conservation in the Western Hemisphere, has identified species declining and facing growing threats across the mid-Atlantic. Nineteen of them were seen in 2019. The ten most often observed:

Grasslands

Populations of field sparrows have fallen by more than 50% across the Northeast, yet they were the third most common bird in the park's grassland sites. Red-winged blackbirds, common yellowthroats and song sparrows were also abundant there. The brief says that continued and improved management of warm-season grass meadows should help grassland species that are now very rare in the park, such as grasshopper sparrows.

Figure 1. Ten most abundant birds in grassland sites in 2019, by average number observed per site. National Park Service.

Forests

The gray catbird, a common and widespread species, was the most abundant bird at forest sites. The fourth most common was the wood thrush, a species of regional conservation concern that depends on larger intact forests. With urbanization increasing around the park, the brief says the wood thrush's abundance shows how important the park's forests are to local birds.

Figure 2. Ten most abundant birds in forested sites in 2019, by average number observed per site. National Park Service.

Forest bird community index

Scientists can judge the overall health of a bird community from the abundance of all its species. The forest bird community index for Valley Forge indicates a moderately healthy community, described as medium integrity. Because the park is relatively small and surrounded by urban land, it may be hard for it to support a full forest bird community, but it does give birds a forested refuge from surrounding development, and keeping its forest healthy matters to local birds.

Figure 3. Forest bird community index score, 2009 to 2019. National Park Service.

Sources

• National Park Service, Mid-Atlantic Network, "Breeding bird monitoring at Valley Forge National Historical Park: 2019 status and trends" (https://www.nps.gov/articles/000/breeding_birds_2019_vafo.htm); the brief points to the park's 2019 breeding bird monitoring report on the NPS DataStore. A photo of a common yellowthroat credited to a private photographer and a contact name are left out; rewritten in hubnx's own words.