In New Jersey, threatened birds find refuge in one of the most populated areas of the state.

New Jersey is the most densely populated state in the US, with over one third of the 50 most densely populated cities in the country existing in the New York Metropolitan area of the state. The population continues to boom in places like Jersey City where new business and residential developments and proximity to Manhattan have made the downtown neighborhood highly desirable. This kind of sprawling urban development is the number one cause of habitat loss and critical population declines in bird species. Approximately 40 percent of New Jersey’s threatened and endangered wildlife are birds, but surprisingly, many of these rare species can be spotted right nearby the bustle of Jersey City.

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Despite its urban location, Liberty State Park is a magnet for bird diversity

 The Jersey City waterfront is home to Liberty State Park , a vast public open space with hundreds of acres of recreational space and waterfront walkways. The mix of habitats on the main areas of the park attracts a wide variety of birds. The lawns and meadows are occupied by several sparrow species, including the threatened savannah sparrow. Peregrine falcons and American kestrels, both threatened birds of prey in New Jersey, are not an uncommon site. The northern harrier, an endangered bird of prey in New Jersey, is often seen flying low over the park’s marshes. Among the reeds in the marshes, threatened black-crowned night herons and endangered American bitterns hide in an unexpected urban refuge.

The NJ endangered Northern Harrier (above) and NJ threatened Black-crowned Night Heron (below) find refuge at Liberty State Park. (Photos by Claus Holzapfel)

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The most interesting habitat in the park is, unfortunately, one the general public does not get to see. It’s a hidden urban forest that tells the tale of the park’s history through its amazing biological community. Liberty State Park officially opened in 1976. Before that, it was a major transportation hub centered around the Central Railroad of New Jersey. The site was abandoned after the railroad went bankrupt and much of the area was later restored and built into the recreational areas of the park. However, one 250 acre section, the site of an abandoned rail yard, was closed off due to soil pollution and left to grow wild for over 50 years. The area is now considered a “brownfield”, which is defined by the Environmental Protection Agency as a “real property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant”.

Inside the Liberty State Park brownfield, abandoned roads and yards have been taken over by a unique assemblage of native and non-native plant species. The novel vegetative community, and the effects of pollution on certain plant species, has been described Dr. Frank Gallagher of Rutgers University.


I began working at the Liberty State Park brownfield in 2008 as an intern for former park administrator and current Director of Environmental Planning and Design at Rutgers University, Dr. Frank Gallagher. I continued at the site as a Ph.D. student under the advisement of Dr. Claus Holzapfel, head of the Fusion Ecology Lab at Rutgers University in Newark. Much of my research has been focused on the birds at Liberty State Park. Between 2008 and now, I have spent countless hours counting birds in the brownfield, but I never get sick of it. In fact, this site, that many would prefer be converted to a golf course, is one of my favorite places. The diversity of species that exists within the brownfield is astonishing. Many small songbirds, not typically seen breeding in the city, nest throughout the site. During migration, brightly colored warblers swarm the green oasis to rest and refuel on their way to and from their breeding grounds. The fact that so many birds are attracted to the brownfield has raised concerns due to the soil contamination. Fortunately, Holzapfel and his colleagues have shown that the contamination is not a serious risk for birds.

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This Palm Warbler (above) and Black-throated Blue Warbler (below) migrate along the Atlantic flyway, which passes over some of the most developed areas in the country, including Jersey City. According to the prestigious Cornell Lab of Ornithology, migratory birds are among the most threatened by urbanization. Places like Liberty State Park provide a valuable sanctuary along their harsh journey. (Photos by Claus Holzapfel)


Even during the winter months, Liberty State Park is teeming with birds both inside and outside the brownfield. Most impressive, is Holzapfel’s on-going list from the annual Christmas Bird Count, a citizen science program of the Audubon Society, which he heads up every year at the park. The list has reached 100 species as of 2014. This impressive number only includes wintering species. The total number of bird species at Liberty State Park, according to eBird, is close to 275 species!

Claus Holzapfel and graduate student, Julian Rondon, brave the cold during the 2013 Christmas Bird Count at LSP. Citizen science programs like this provide scientists with a huge amount of data that can inform us about species distributions and whether species are experiencing population declines.

Not all of the birds at Liberty State Park are on the threatened or endangered list, but for the most part, they are all threatened by urbanization. According to the State of the Birds Report, an alarming number of “common” species are experiencing steep declines and action is needed to ensure these birds remain common. The resilience of life in Liberty State Park can help researchers learn how birds and other organisms can survive in the face of human development.

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The world is constantly changing and developing. In the US, our cities are expanding rapidly. Holzapfel sees Liberty State Park as a glimpse into the future of biological communities where organisms must adapt to the compounding threats of urbanization and climate change. By looking at how plants and birds survive and assemble at Liberty State Park, where areas are polluted and carbon dioxide levels are elevated, we can try to understand how to conserve species in the long run. Currently, Gallagher has developed plans to revitalize the park’s brownfield region and integrate it into the surrounding park. The goal is to create a unique educational and recreational resource for park goers, while preserving certain areas as wildlife refuge and a site for on-going scientific research.

Liberty State Park is a Jersey City treasure that serves as green oasis for both humans and birds. Unfortunately, the fate of the park has recently come into question with the unveiling of new legislation that critics claim could sneak Liberty State Park into the hands of developers. The Department of Environmental Protection oversees the park, but some are saying language in the new bill will allow a newly appointed commission to bypass the DEP and privatize areas of the park, particularly the waterfront with picturesque views of New York City and the Statue of Liberty. The bill has not yet been signed by Governor Chris Christie, and opposition is rising as news spreads about the threat of losing Liberty State Park. This news is certainly alarming to those of us who work at the park and know what this site means for biological conservation and restoration. For me, it’s been a wake-up call to get the word out about the need to preserve the habitats of Liberty State Park as a refuge for threatened birds. The scientific and conservation value of the park adds a whole new dimension to current efforts to block development, and it’s time everyone hears about it.

Read more about birds in abandoned urban places here

News articles on the LSP legislation controversy can be seen here and here.