INVENTORY OF ODONATA (DRAGONFLIES AND DAMSELFLIES) AT SAGAMORE HILL NATIONAL HISTORIC SITE

Natural Resource Technical Report
NPS/NCBN/NRTR—2010/192

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

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

February 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 Sagamore Hill National Historic Site (SAHI) 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, records of odonates provided by NPS staff, and consultation with local amateur odonatists. Each site was surveyed using the checklist technique, which entailed 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.

During 2004 and 2005, 22 odonate species were recorded across 7 survey sites at SAHI. The most abundant odonate species were common green darner (Anax junius), fragile forktail (Ischnura posita), great blue skimmer (Libellula vibrans), and black saddlebags (Tramea lacerata). One state-listed species, comet darner (Anax longipes), was recorded at Field East Lot during 2004. This was the first recorded sighting of a comet darner in Nassau County and the only sighting of this species at the 3 National Parks in New York and New Jersey that were surveyed for odonates. Compared to the other National Parks (e.g., Fire Island National Seashore and Gateway National Recreation Area) surveyed for odonates during 2004 and 2005, SAHI contained fewer species and lower abundances of odonates. This is likely because SAHI lacks suitable breeding habitat. Nonetheless, results from this study doubled the number of known species within Nassau County.

Overall, SAHI contains good foraging habitat and potential habitat for migrating odonates, but lacks suitable breeding habitat. In general, odonates require permanent or temporary standing water to reproduce. Similarly, habitats with standing water usually support the greatest diversity and abundance of odonates. During 2004 and 2005, seasonal freshwater ponds at SAHI, such as Heron and Hog Pond, supported little breeding activity. Similarly, the salt marsh at Beach/Marsh lacked well developed salt pannes and did not support breeding odonates. We assume that most of the odonates recorded at SAHI are breeding in temporary waters in residential areas located within flying distance of the Park and are using the fields at SAHI for cover and feeding.

Fields were the most widely used and important habitat for odonates at SAHI. In general, fields support a broad assemblage of prey for odonates, provide cover from predators, provide shelter when temperatures drop at night, and provide perches where odonates can rest between feeding. At SAHI, larger fields showed greater species richness and supported greater abundances of odonates compared to smaller fields. In particular, Field East Lot and Field West of House supported the greatest species richness and abundance of odonates. In general, researchers noted that un-mowed fields appeared to support more odonate activity than mowed fields.

Although we did not observe any migration events during our study, we believe that odonates likely use the fields at SAHI during migration, largely because SAHI is located within the odonate migration corridor and within a heavily developed landscape. In addition, many of the species we recorded in fields at SAHI are migratory, including common green darner, black saddlebag, wandering glider (Pantala flavescens), and spot-winged glider (Pantala hymenaea).

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