INVENTORY OF ODONATA (DRAGONFLIES AND DAMSEL FLIES) AT FIRE ISLAND NATIONAL SEASHORE

Natural Resource Technical Report NPS/NCBN/NRTR—2010/295

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

Rhode Island Natural History Survey
P.O. Box 1858
Kingston, RI 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 Fire Island National Seashore (FIIS), 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.

Because odonates are aquatic insects, potential breeding habitat was located by examining maps associated with an amphibian and reptile inventory conducted by the Wildlife Conservation Society in 2002, aerial photos, topographic maps, wetland maps provided by NPS staff, and consultation with local amateur odonatists. Databases and museum collections were also researched for historic records.

Each site was walked using a 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.

Twenty-seven odonate species were documented across 18 of the 34 sites surveyed at FIIS 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). Both of these species were documented in 2004; however, only Needham’s skimmer was documented in 2005. The most widely distributed species at FIIS included common green darner (Anax junius), seaside dragonlet (Erythrodiplax berenice), painted skimmer (Libellula semifasciata), and spot-winged glider (Pantala hymenaea).

In general, survey sites at FIIS contained appropriate migratory and foraging habitat, but generally lacked habitats appropriate for odonate reproduction, because few areas contained ponds, lakes, or streams with permanent water. Of all sites surveyed at FIIS, Kismet Pond showed the greatest species richness and abundance of odonates, largely due the permanent water levels observed during 2004 and 2005. Also, Needham’s skimmer, a state listed species in New York that is typically associated with coastal pond habitats, was found to in large numbers at Kismet Pond.

Survey sites at the William Floyd Estate primarily served as foraging habitat for odonate species. We found that the larger fields (Field F12, G7, H9) showed greater species richness and abundance of odonates. Needham’s skimmer was recorded in two fields (e.g. Field F12 and H9) at the William Floyd Estate. Based on the habitat available at the William Floyd Estate, we expected to find greater diversity of foraging odonates than what was observed and suspect that the generally dry weather during 2005 may have reduced the number of foraging odonates in a these habitats. It is also possible that spraying for mosquitoes in surrounding towns also reduced food supplies for foraging odonates.

FIIS is located within the odonate migration corridor and offers important habitat for migrating odonates. In particular, several sites at the Otis Pike Wilderness Area (OPWA) possess high conservation value for odonate migration, including both Bellport Salt Marsh and Bellport Beach. Both of these areas have shown to support migration events during fall migration. Although migration events were not observed during odonate surveys, a migration event of common green darners was documented by one researcher at Bellport Beach during September of 2004. Given its location along the Atlantic coast, the Bellport Beach area is likely to also provide habitat for other species of odonate during migration, such as blue dasher (Pachydiplax longipennis), black saddlebags (Tramea lacerata), Carolina saddlebags (Tramea carolina), and swamp darner (Epideschna heros).

In general, current management practices at most survey sites appear to have either a neutral or beneficial effect on odonate populations at FIIS. For example, FIIS protects its vegetative communities by prohibiting off-road vehicle use, except in designated areas, and foot traffic, except on marked trails, roads, or boardwalks. Both of these measures, by design, protect fragile habitats (e.g. northern interdunal cranberry swale, northern bayberry dune shrubland, etc.) commonly used by odonate species. We note that the greatest threat to odonate breeding habitat and similarly, odonate populations in general, is the abundance of common reed (Phragmites australis) at many odonate survey sites, including Bellport Salt March, Kismet Pond, and Watch Hill Marsh. 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 surveys several sites, including Kismet Pond, the Seep, and Teal Pond that common reed be monitored and if deemed necessary, managed for at Bellport Salt March, Kismet Pond, and Watch Hill Marsh.

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