INVENTORY OF ODONATA (DRAGONFLIES AND DAMSELFLIES) AT GATEWAY NATIONAL RECREATION AREA

Natural Resource Technical Report
NPS/NCBN/NRTR—2010/296

Nina Briggs, Eric G. Schneider, Jackie Sones,
and Kristen Puryear

Rhode Island Natural History
P.O. Box 1858
Kingston, Rhode Island 02881

March 2010

U.S. Department of the Interior
National Park Service
Natural Resource Program Center
Fort Collins, Colorado

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Executive Summary

For the National Park Service to effectively maintain the existing dragonfly and damselfly (Class Insecta, Order Odonata) diversity of Gateway National Recreation Area (GATE) baseline knowledge of the present odonates assemblage is critical, including habitats within the park that support odonates and the abundance and viability of selected odonate species at such sites. To help meet this goal, we focused on three main objectives. The first objective was to conduct a comprehensive baseline inventory of adult odonates. The second objective was to document status, distribution, and relative abundance of rare species found within the park. The third objective was to document odonate migration events and behavior.

Potential survey sites containing breeding, feeding, and migrating habitats were identified by examining aerial photos, topographic maps, wetland maps and records of odonates provided by NPS staff, and consultation with local amateur odonatists. Databases and museum collections were also researched for historic records. Each site was surveyed using the checklist technique, which entails actively searching out odonates so that they could be caught and identified. Male and female vouchers were taken whenever possible at each site. Individuals that evaded capture but could be confidently identified in flight were recorded as sight records on field data sheets. Surveys were conducted once a month during the flight season, from May through September in 2004 and 2005.

Thirty-seven odonate species were recorded across 38 sites surveyed at GATE during 2004 and 2005. Two of these species are state listed in New York, Needham’s skimmer (Libellula needhami) and Rambur’s forktail (Ischnura ramburii). Of the three National Parks in New York and New Jersey surveyed for odonates during 2004 and 2005 (Fire Island National Seashore, Sagamore Hill National Historic Site, and GATE), GATE showed the greatest species richness and number of sites with odonate species. The most abundant odonate species at GATE were familiar bluet (Enallagma civile), blue dasher (Pachydiplax longipennis), citrine forktail (Ischnura hastata), and swamp darner (Epiaeschna heros). Overall, GATE contains several marshes and coastal ponds that contained permanent water and emergent vegetation and supported odonate breeding. In addition to supporting breeding odonates, several sites at GATE offered good foraging habitat and cover for migrating odonates.

Due to its location within the odonate migration corridor and especially considering the level of development in the surrounding landscape, GATE offers critical habitat for migrating odonates. Migrating odonates were observed during both years of this study in the Jamaica Bay Unit at Fort Tilden and at Breezy Point. On several occasions researchers observed odonates funneling over the dunes at Fort Tilden Fishlot en route to Breezy Point Swales. During much of the migratory period, Breezy Point Swales was teaming with migratory odonates and generally offered excellent foraging habitat and cover to migrating odonates. At the Sandy Hook Unit, Newest Pond and Spermaceti Cover Inner Salt Marsh also supported migratory odonates, offering good foraging habitat and cover during the migratory period. Given the location of the Sandy Hook Unit, it’s possible that some of the migratory odonates observed at Breezy Point migrated over the ocean and stopped-over at Sandy Hook before continuing on. Specific results will be presented for each Park Unit (Jamaica Bay Unit, Staten Island Unit, Sandy Hook Unit) below.

The Jamaica Bay Unit showed the greatest species richness of the three Park Units at GATE and contains several areas with critical or rare habitat, such as coastal ponds, dunes, and swales, which not only support odonate breeding, but also provide foraging areas, cover, and habitat for migrating odonates. For example, both Big John’s Pond and West Pond at Jamaica Bay Wildlife Refuge (JBWR) contained permanent water and emergent vegetation that supported considerable odonate activity, even when water levels were low. In addition, these sites provided breeding habitat for two state-listed species, Rambur’s forktail and Needham’s skimmer. As mentioned above, the dunal system and beach at Fort Tilden Fishlot and, in particular, Breezy Point Swales offered excellent foraging habitat and cover to migrating odonates.

The Staten Island Unit contains generous open space amongst a heavily developed landscape, but generally lacks permanent water and abundant habitat that can be used for breeding by odonates. However, sites that contain permanent water such as Freshwater Pond and Peeper Road provided good foraging and breeding habitat for a suite of odonate species, including two state-listed species, Rambur’s forktail and Needham’s skimmer. In addition, the dunes and beach at Miller’s Field provided foraging and potential migration habitat for several odonate species.

The Sandy Hook Unit contains several unique coastal habitats, including sand dunes, salt and freshwater marshes, freshwater ponds, and shrub thickets, that provided valuable foraging, breeding, and migratory habitats for odonate species. Of particular importance to breeding odonates were freshwater ponds with permanent water such as Newest, North, and Exclamation Point Pond. As noted above, Newest Pond and Spermaceti Cover Inner Salt Marsh provides critical habitat used by many migrating odonates.

In general, current management practices at most survey sites appear to have either a neutral or beneficial effect on odonate populations at GATE. The most serious threat to odonate populations and habitat appears to be the abundance of common reed (Phragmites australis) at many odonate survey sites, including JBWR Big John’s Pond, Peeper Road at Great Kills Park, and Exclamation Point Pond and North Pond at Sandy Hook. In fact, nearly all of the permanent and temporary water used by odonates at GATE were surrounded, to some degree, by common reed. Common reed out competes native plants, changes invertebrate abundance and assemblages, affects site hydrology, and can reduce diversity of damselfly species.

We recommend that in addition to continuing odonate surveys at several of the most productive sites, including JBWR Big John’s Pond and Peeper Road and Freshwater Pond at Great Kills Park, that common reed be monitored and if deemed necessary, managed for at Peeper Road and Freshwater Pond at Great Kills Park. In addition, we suggest that monitoring for migration events at Fort Tilden Fishlot at the Jamaica Bay Unit.

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