Grassland Birds of New Jersey

Part II: Restoring Critical Breeding Habitat

by Meghan Kolk, Wildlife Biologist

In Part I of this series, I discussed the drastic loss of grasslands in New Jersey and the importance of preserving and restoring this disappearing habitat for grassland-dependent bird species.  Due to this habitat loss, in much of the northeastern United States (including New Jersey) airports have become significant breeding grounds for many threatened and endangered grassland birds.  In fact, airports are often the only suitable habitat available for New Jersey’s rarest grassland bird, the upland sandpiper.  If these large expanses of open fields are managed properly, they can support nesting birds while still remaining safe for aircraft operation.  This is the goal of CWF’s new restoration project at one of the most critical breeding sites in New Jersey.

The Joint Base McGuire-Dix-Lakehurst (JBMDL) in central New Jersey hosts the largest known breeding colony of the endangered upland sandpiper (Bartramia longicauda), and the second-largest known breeding colony of the threatened grasshopper sparrow (Ammodramus savannarum) in the State.  The bobolink (Dolichonyx oryzivorus), savannah sparrow (Passerculus sandwichensis), horned lark (Eremophila alpestris) (all threatened) and eastern meadowlark (Sturnella magna) (special concern) all make a home here as well during the nesting season.  CWF has  partnered with the U.S. Fish and Wildlife Service to restore hundreds of acres of this vital land to increase suitability and to alter management practices to benefit both wildlife and airfield operations.

Lakehurst, which lies at the northern border of the Pinelands National Reserve, has sufficient grassland habitat to support breeding birds; however, some of the most attractive fields contain large bare areas due to the sandy soil or overgrowth of competitive vegetation.  The goal at this site is to fill in the gaps to increase the overall size of suitable habitat and to reduce fragmentation. Over the spring and fall of 2017, over 100 acres of land were seeded with native warm-season grasses and pollinator plants.  Native warm-season grasses are preferred by nesting grassland birds because of their clump-forming nature.  Unlike a thick mat of grass which we are accustomed to on our lawns, clump-forming grasses give birds the ability to forage, seek cover, and build nests in the spaces between the clumps.  The addition of pollinator plants to the grass mix creates an added benefit to a multitude of pollinator species.

At McGuire, the airfield also currently supports nesting. The issue here is the aircraft safety regulation that calls for the grass height to remain between seven and fourteen inches.  The existing cool-season grasses and other vegetation grow at a rate that requires mowing during the nesting season in order to maintain the proper height.  Since nests are constructed directly on the ground, mowing during the nesting season can destroy eggs and unfledged chicks. Our goal at this site is to convert the airfield completely to native warm-season grasses and forbs that are beneficial to wildlife and will remain within the range of seven to fourteen inches throughout the nesting season.  This will ensure that mowing will not be necessary until nesting is complete. This conversion will be a long-term project spanning several years, with the first phase beginning in the spring of 2018.

Although JBMDL is an important breeding site for many species of grassland birds, it is particularly important for the upland sandpiper, and is currently one of only three known sites in New Jersey that supports upland sandpiper breeding.   In Part III of this series I will go into detail about this rarely-seen, but fascinating bird that is quickly disappearing from New Jersey.

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