Bombay Hook National Wildlife Refuge

Thousands of snow geese take flight at Bombay Hook National Wildlife Refuge on 31 October 2014. Photo by Abby Walter
Thousands of snow geese take flight at Bombay Hook National Wildlife Refuge on 31 October 2014. Photo by Abby Walter

While there are several different ecosystem types present at Bombay Hook National Wildlife Refuge, tidal marsh is strongly in the majority.

“This is a 16 thousand acre refuge, and 12 thousand of those acres are tidal marsh,” explained regional biologist Susan Guiteras of the US Fish and Wildlife Service. Such a large expanse of saltmarsh is particularly rare on the eastern coast; it makes up the largest stretch of saltmarsh north of Virginia that has not faced significant alterations. The size and quality of this marsh makes it especially important for migratory birds, which use Bombay Hook as a midway stopover point along the Atlantic flyway. The saltmarsh requires minimal management on the part of the biologist staff, but does afford significant research opportunities, including with the University of Delaware.

A system of dikes allows biologists at Bombay Hook NWR to manage their freshwater impoundments also to cater to the migratory birds of each season. Primarily fed by rainwater and runoff, the impoundments are lowered during the spring to expose mudflats for migratory shorebirds (known as a slow spring drawdown). During the summer, vegetation germinates and grows thicker. By fall, the impoundments are allowed to refill until shallow water has accumulated for ducks and other waterfowl. This temporally flexible management strategy allows the ecosystems to be ideal for each round of migrants throughout the year. The dike system, however, is currently in need of replacement. Blockades have begun to rust away, preventing sufficient control of water movement. A recent collaboration with Ducks Unlimited will provide entirely new dikes for the refuge.

Bombay Hook NWR also contains a significant amount of upland fields. Until 2010, these fields were a mix of natural grasslands, managed by the Bombay Hook staff, and agricultural fields, managed by private farmers. Historically, this had been a mutually beneficial arrangement: farmers were given land to grow crops, and the traditional practices meant that the agricultural fields provided habitat for wildlife when not in season. However, farming practices have drastically changed in the past several decades, without reevaluation by the Bombay Hook management to make sure that practices were still ultimately beneficial to wildlife. With recent lawsuits by bird advocacy groups, Bombay Hook NWR halted all agricultural practices on the refuge in 2010. Because these many acres were reclaimed all at once, management was not able to keep up with such a huge change, and invasive species have come to dominate the upland fields. This predicament illustrates the importance of strategic and well thought-out management changes, whenever they are possible.

Bombay Hook NWR is a testament to the potential success of coastal wetland management at a time when this ecosystem type faces a myriad of threats, both natural and anthropogenic. Natural subsidence, periodic storms, and changing tides are constant drivers of wetland loss. Normally, a coastal wetland may be able to persist against such threats, but the addition of human-induced factors makes resilience more difficult. Sea level rise, accelerated by climate change, could mean loss of 20-60% of the world’s coastal wetlands in this century if these ecosystems are not able to migrate inland quickly. Pollution and nutrient runoff pose health risks for wetland wildlife, and can lead to toxic algal blooms. Human development of wetlands, such as dredging and filling, as well as alterations to the hydrology caused by dams and other structures, can lead to physical wetland loss or saltwater intrusion. With so many dangers facing coastal wetlands today, Bombay Hook NWR remains as an example of effective management of these ecosystems in peril.