Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 141 2019 NORTHEASTERN NATURALIST 26(1):141–154 Nymph Ecology, Habitat, and Emergence-site Selection of Cordulegaster erronea Hagen (Tiger Spiketail Dragonfly) in New Jersey with Implications for Conservation David Moskowitz1,* and Michael L. May2 Abstract - Cordulegaster erronea (Tiger Spiketail) is of conservation concern throughout much of its range; yet only a single study on the nymphs has been conducted, and many aspects of the species’ life-history are poorly understood. The present study evaluated the size, age structure, and density of Tiger Spiketail nymphs at a stream on the Schiff Reservation Natural Lands Trust (Schiff) in Mendham Township, Morris County, NJ. We investigated the habitat and surrounding landscape characteristics of this stream and a second stream containing Tiger Spiketails at Schiff. We collected and measured 137 Tiger Spiketail nymphs during this study—82 in the spring and 55 in the fall—representing pre- and postadult emergence. We found 24 exuviae along both study streams and an additional 8 exuviae along 3 other streams in New Jersey, Connecticut, and Delaware. We are aware of only 1 other published report of Tiger Spiketail exuvia, which documented a single specimen. Our data and habitat assessment indicate that the Tiger Spiketail has a long nymphal stage and may be dependent upon high quality, fish-free, perennial headwater streams flowing through extensive forests. This information may assist resource managers in developing conservation strategies and habitat-protection measures for this species. Introduction Dragonflies are model organisms for ecological and behavioral studies (Corbet 1999, Cordoba-Aguilar 2008), and their primitive origins and ecological and behavioral diversity are well suited to investigate insect evolution and ecology (Suhonen et al. 2008). Dragonflies are also a bridge between aquatic and terrestrial environments. Many dragonfly species are declining; therefore, they should be an important component of habitat-conservation priorities. The Cordulegastridae or Spiketails are a small but almost cosmopolitan family of dragonflies (Needham et al. 2000). Most Cordulegaster species have limited geographic ranges and are patchily distributed within habitats that are likely highly sensitive to disturbance (Corser et al. 2014, White et al. 2014), and many of them are also of conservation concern (IUCN 2015, NatureServe 2015). However, comprehensive life histories for most Cordulegaster species are lacking. Cordulegaster species have long nymphal stages, and individuals take from 2 to 5 years to reach maturity (Corbet et al. 2006, Glotzhober 2006, Marczak et al. 2006). Cordulegaster nymphs are shallow burrowers (Corbet 1999) dependent upon specific microhabitats within their breeding streams and seepages (Boda et 1EcolSciences, Inc., 75 Fleetwood Drive, Suite 250, Rockaway, NJ 07866. 2Rutgers University Department of Entomology, New Brunswick, NJ 08901. *Corresponding author - dmoskowitz@ecolsciences.com. Manuscript Editor: Joshua Ness Northeastern Naturalist 142 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 al. 2015a, Corbet 1999). A combination of factors appears to be important, including sediment size and composition (Hager et al. 2012, Marczak et. al. 2006), water quality (IUCN 2015), current (Lang et al. 2001), and geology (Tamm 2012). For most species, nymphal studies are limited to a single location. Recent research has explored aspects of nymph life-history for Cordulegaster sayi Selys (Say’s Spiketail) in Georgia (Stevenson et al. 2009), Cordulegaster maculata Selys (Twin-spotted Spiketail) in Virginia (Burcher and Smock 2002), Cordulegaster diastatops Selys (Delta-spotted Spiketail) and Twin-spotted Spiketail in New York (Hager et al. 2012), and Cordulegaster dorsalis Hagen (Pacific Spiketail) in British Columbia, Canada (Marczak et. al. 2006). Similar nymphal studies in Europe have investigated other Cordulegaster species (Ferreras-Romero and Corbet 1999, Liebelt et al. 2010/2011, Müller and Waringer 2001). Despite Cordulegaster erronea Hagen (Tiger Spiketail) being listed as threatened, endangered, critically imperiled, special concern, or of greatest conservation concern throughout most of its range (NatureServe 2015), only a single study focusing on the nymphs has been conducted (Glotzhober 2006). In New Jersey, the site of our research, the Tiger Spiketail is described as imperiled (Natural Heritage State Rank of S2) and is listed as a species of special concern by the New Jersey Endangered and Nongame Species Program. The goal of this study was to determine the habitat parameters for this rare species and to help resource managers develop appropriate conservation strategies. The present study evaluated the size, age structure, and density of Tiger Spiketail nymphs at a stream in New Jersey. We described the habitat and surrounding landscape characteristics of this stream and a second nearby stream containing Tiger Spiketails. We made exuvial collections at these streams and at 3 others in New Jersey, Delaware, and Connecticut. Study Organisms Tiger Spiketail nymphs burrow shallowly in stream sediments and possibly seepages (Glotzhober 2006; D. Moskowitz, pers. observ.) and are highly cryptic. Unless they are moving, they can be very difficult to discern from the substrate. Their dorsal surface is also densely hairy and commonly coated with sand grains adding to their crypsis. We observed adults flying on the study streams from 1 July to 8 September. In 2015, we detected the earliest exuviae along these streams on 1 July, indicating a flight period beginning earlier (D. Moskowitz, pers. observ.). In New Jersey, the earliest reported flight date is 20 June (May and Carle 1996), and the previous late date was 5 September (Bangma 2006). Study Site We sampled for nymphs and collected exuviae at streams where Tiger Spiketails breed on the Schiff Reservation Natural Lands Trust (Schiff) in Mendham Township, Morris County, NJ (40.7644°N, 74.6209°W). Both streams are perennial headwaters fed by numerous groundwater seepages; they flow through mature deciduous forest Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 143 that has remained uncut since at least the 1930s. The streams, which are described in Moskowitz and May (2017), appear similar in landscape position, surrounding habitat, hydrology, soils and geology to other streams where Tiger Spiketails breed in New Jersey (Barlow 1995; D. Moskowitz, pers. observ.), Ohio (Glotzhober 2006), New York (NYNHP 2012) and elsewhere in the range (Needham et al. 2000). Both Tiger Spiketail streams are located at the bottom of valleys in the Highlands Physiographic Province of New Jersey, which is characterized by a series of flat-topped ridges composed of crystalline, igneous, and metamorphic rocks separated by deep, narrow valleys underlain by less-resistant limestone and shale (Robichaud and Buell 1983). The surficial geology of the 2 study streams consists of alluvium and colluvium deposited in floodplains and the headwater areas of valleys underlain by weathered gneiss (NJDEP 2006). The bedrock geology, as mapped by the NJDEP (1999), is primarily medium- to fine-grained granite and fine- to coarse-grained gneiss. Mapped soils consist largely of the Edneyville- Parker-Califon Soil Series Association (USDA–NRCS 2008). The dominant soils are deep, excessively drained to somewhat poorly drained, gently sloping to steep, gravelly, sandy or stony loams weathered in place from bedrock or moved a short distance and redeposited in waterways. Minor soils range from well drained to poorly drained (Eby 1976). Field observations indicate that very poorly drained, mucky, highly organic soils also occur adjacent to the streams and seepages of the study habitats. The stream bottoms are sands and gravels with little organic matter. The 2 study streams have highly stable hydrology and continual flow even during an intense drought, when the yearly rainfall total was approaching a 25% deficit (National Weather Service 2019). An analysis of GIS data and field reconnaissance indicate the forested nature of both study streams. We determined the approximate extent of the 2 watersheds inhabited by Tiger Spiketail through analysis of a combination of the USGS 7.5' topographic quadrangle and digital elevation model. We clipped land use/land cover and soils data to the approximated watershed boundary. The drainage areas of the McVickers Brook and the unnamed tributary to the North Branch Raritan River tributary are 71.2 ha and 25.1 ha, respectively. Both streams have drainage basins that are largely wooded (McVickers Brook tributary: 79.4% forest cover; unnamed tributary: 95% forest cover). Single-family residential development was constructed within the McVickers Brook tributary drainage basin between 1995 and 2002 and comprises 15.7% of the area. Two single-family homes are present in the drainage area of the unnamed tributary and comprise 5.2% of that drainage basin. Methods In order to find Tiger Spiketail nymphs for this study, we sifted stream sediments through a 0.5 m x 0.5 m mesh-lined open-frame box. The mesh was hardware cloth with 1-mm openings. We hand-shoveled stream sediments into the mesh frame and then gently swirled stream water through the box to remove silt and other fine particles, leaving only sand and cobbles behind. Even very small nymphs were easily found using this method (Fig. 1). Northeastern Naturalist 144 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 Figure 1. (A) Sieve box used to sample for Tiger Spiketail nymphs. (B) Exhibit of the variety of sizes of Tiger Spiketail instars found in the study stream on a single day. (C) D. Moskowitz inspecting and pointing at an exuvia located on a tree along one of the study streams at Schiff Reservation, NJ. Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 145 In order to survey the size and abundance of nymphs, we sampled the study stream on 8 and 12 October 2009 and then again on 24, 25, 26, and 30 April 2010 in two 10-m–long study plots. We selected the April and October sampling dates to describe pre- and post-emergence nymph characteristics. We attempted to find every nymph in the study plots by sampling all areas of loose sediment and gravel. The April sample was located ~10 m upstream of the October sample in order to minimize the potential for downstream movement of nymphs between the 2 study periods. Both study plots appeared to exhibit similar characteristics. We measured the width of the stream at each 10-m sampling location at 1-m intervals to obtain an average width for estimating nymph densities. To reduce stress and handling of the nymphs, we used a hand-lens and ruler to measure the maximum head width and total body length for each nymph in the field (estimated to the nearest 0.5 mm). After measuring, we released each individual at the collection location. We also measured the head width and body length for each exuvia using a hand-lens and ruler (estimated to the nearest 0.5 mm), provided that the head and/or entire body were present. We conducted searches for exuviae during 2014 and 2015 to determine the location of adult emergence and other characteristics of emergence-site selection. In both years, we regularly searched all trees within ~20 m of the streams for exuviae from 15 June to 1 September. We searched trees visually and with binoculars (Swift Audubon 8 x 42). When an exuvia was discovered, we recorded distance from stream, height above the ground, and tree species (or other location details if not on a tree). We used a hand lens and a ruler to measure (to the nearest 0.5 mm) head width and body length for each exuvia. Tiger Spiketail exuviae are readily identified by the distinctive spatulate setae on the frontal shelf and the shape of the epaulet (Needham et al. 2000). Results Nymph distribution We collected and measured 137 Tiger Spiketail nymphs during this study, 82 in the spring and 55 in the fall (Fig. 2, Table 1). The data collected indicates that Tiger Spiketail is parti-voltine in New Jersey, as in Ohio (Glotzhober 2006). Both the April and October sampling periods, representing pre-and post-emergence of the adults, indicated multiple sizes reflecting multiple age classes. Nymphs in the spring had maximum head widths varying from 2 mm to 8 mm (mean = 3.94 ± 2.0 mm) and total body lengths varying from 10 mm to 37 mm (mean = 16.14 ± 7.47 mm). In the fall, nymphs had maximum head widths varying from 1 mm to 8 mm (mean = 5.15 ± 1.32 mm) and total body lengths varying from 5 mm to 33 mm (mean = 22.04 ± 4.97 mm) (Table 1). The average density of nymphs per square meter of stream bottom was 0.112 in the spring sample and 0.086 in the fall sample. Exuviae distribution During the study, we found 24 exuviae along the streams at Schiff. We found the earliest exuviae on 1 July 2015 and the latest on 30 July 2014. We detected Northeastern Naturalist 146 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 exuviae (21 total) on all of the tree species present within 10 m of the streams, including: Betula lenta L. (Black Birch), Betula alleghaniensis Britton (Yellow Birch), Acer rubrum L. (Red Maple), Fagus grandifolia Ehrh. (American Beech), Ulmus americana L. (American Elm), and Acer saccharum Marsh. (Sugar Maple). Figure 2. (A) spring (n = 82), (B) fall (n = 55) head width (mm) of Tiger Spiketail nymphs from a stream in New Jersey, and (C) exuviae (n = 24) head widths from New Jersey, New York, and Connecticut streams. Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 147 One exivia was on Polystichum acrostichoides (Michx.) Schott (Christmas Fern), 2 were on Berberis vulgaris L. (Common Barberry), and 1 was on the ground near the base of a tree. Of the 20 exuviae found on trees, 17 were on the trunk, 2 were on small branches, and 1 was on a leaf. We found 22 exuviae singly and 2 were on the same tree ~31 cm apart. All but 2 exuvia were encrusted with sand grains and small pebbles; 1 was also heavily stained red. Exuviae distance from the stream varied from 76 cm to 518 cm (mean = 222 ± 124 cm). Their height above the ground was 0 cm to 229 cm (mean = 132 ± 60 cm). Four of the emergence trees were at the top of steep slopes that required the nymph to climb to reach the tree. Stream banks below the emergence sites were also often deeply undercut and nearly vertical, and, assuming a direct path from stream to tree, nymphs had to traverse these areas. The head width of the exuviae varied from 6.5 mm to 9.0 mm (mean = 7.8 ± 0.4 mm. Body length varied from 34 mm to 40 mm (mean = 37.1 ± 1.4 mm. The October nymph-sampling event found no nymphs with a head width of 7.1–7.5 mm but a small percentage (5.5%) with a head width of 7.6–8.0 mm. During both sampling periods, we collected a broad range of nymphal instars in the study plots, reflecting an overlap of cohorts resulting from the long nymphal period. In late June, we searched along 2 other streams for Tiger Spiketail exuviae, 1 in Fairfield County, CT, at the Trout Brook Valley Conservation Area, and the other in Hunterdon County, NJ, at the South Branch Reservation. We also visited a 3rd stream, at White Clay Creek State Park in New Castle County, DE, in mid-July. At those 3 sites, we searched all trees within ~10 m of the streams for exuviae. We detected 9 exuviae during the searches; 4 each on trees along the New Jersey and Connecticut streams and 1 along the Delaware stream. All 4 exuviae along the Connecticut stream were on trees—2 on Sugar Maple and 2 on Tsuga canadensis (L.) Carrière (Eastern Hemlock)—and all were lightly to heavily encrusted with sediments. The distance from the stream for these exuviae varied from 61 cm to 152 Table 1. Distribution of Cordulegaster erronea specimens sampled by head width for: nymphs from New Jersey; exuviae from New Jersey, New York, and Connecticut; and nymphs from Ohio. Stadia instar classes and Ohio data from Glotzhober (2006), who did not assign instar classes for nymphs with headwidths smaller than 3.0 mm (NA= not assigned). Ohio sampling New Jersey nymph sampling Exuviae Head width Spring Fall Spring Fall sampling (mm) Stadia (n = 162) (n = 139) (n = 82) (n = 55) (n = 24) less than 1.0 NA 0 0 0 0 1.0–1.4 NA - 10 0 4 1.5–1.9 NA 16 38 0 1 2.0–2.4 NA 29 17 2 14 2.5–2.9 NA 27 15 1 2 3.0–3.8 F4 46 28 3 5 3.6–4.5 F3 34 12 11 9 4.5–5.7 F2 7 11 46 7 5.8–6.8 F1 1 7 8 6 7.0–9.0 F0 1 1 11 7 24 Northeastern Naturalist 148 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 cm (mean = 122 ± 37.3 cm). The height above ground varied from 91 cm to 152 cm (mean = 130 ± 5 cm). Exuvial head width varied from 7.5 mm to 8.5 mm (mean = 8.1 ± 0.4 mm) and body length varied from 36 mm to 40 mm (mean = 38.0 ± 1.6 mm). We also found all 4 of the New Jersey exuviae on trees along the stream: 1 on Black Birch, 2 on Eastern Hemlock, and 1 on American Beech. All of the exuviae were lightly to heavily encrusted with sediments. The distance from the stream for those exuviae varied from 31 cm to 777 cm (mean = 400 ± 281 cm) and the height above the ground varied from 76 cm to 152 cm (mean = 118 ± 33 cm). Head width varied from 8.0 mm to 8.5 mm (mean = 8.4 ± 0.3 mm) and body length varied from 37.5 mm to 38 mm (mean = 37.8 ± 0.5 mm). We found the single exuvia along the stream in Delaware on a Red Maple 76 cm from the stream and 117 cm above the ground; it was heavily encrusted. The head width and body length could not be determined as the exuvia lacked the head. Odonate fauna of the study streams We observed few odonates other than Tiger Spiketail on the study streams at Schiff; no exuviae or nymphs except those of Tiger Spiketail were encountered during this study. With the exception of Calopteryx maculata Palisot de Beauvois (Ebony Jewelwing), which were commonly encountered, and Somatochlora tenebrosa Say (Clamp-tipped Emerald), with about 4 males and 2 females noted in late August, the only other odonates observed during this study were limited to single individuals of Lanthus vernalis Carle (Southern Pygmy Clubtail), Somatochlora linearis Hagen (Mocha Emerald), Boyeria vinosa Say (Fawn Darner), Anax junius Drury (Common Green Darner), and Aeshna umbrosa Walker (Shadow Darner). Of these species, we only observed the Clamp-tipped Emerald ovipositing in mossy areas on the stream, which occurred twice. Discussion The goal of this study was to determine the habitat parameters for Tiger Spiketail that might help resource managers develop appropriate conservation strategies. The Tiger Spiketail is a species of conservation concern throughout most of its range yet only a single study has investigated the nymphal habitats (Glotzhober 2006) and there are no published reports about exuviae (except a single exuvia noted in Glotzhober 2006), potentially complicating conservation efforts. Given the broad conservation concern for Tiger Spiketail, a better understanding of the nymphal habitats is necessary to develop appropriate conservation and protection strategies. The range of the Tiger Spiketail puts it at risk from various potential impacts. A significant portion of the New Jersey range falls within some of the wealthiest counties in the country, creating residential development pressures and associated land disturbances (USCB 2019). New Jersey wetland and stream-protection regulations provide for maximum buffers of 45.7–91.4 m (150–300 ft) that are likely inadequate to protect Tiger Spiketail habitat. New Jersey and surrounding states are also facing installation of many new above- and below-ground utility lines, utility line upgrades, and other infrastructure pressures (NJDEP 2019). Many of these Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 149 projects are located in the range of the Tiger Spiketail and at least potentially cross the species habitat. The Tiger Spiketail also occurs in areas of mountaintop mining and the extensive ongoing development of the Marcellus shale natural gas reserves and associated distribution pipelines—activities that may impact the high-quality streams required by the species (Olcott 2011). The Tiger Spiketail has been ranked as having high regional vulnerability, indicating that a regional conservation strategy is necessary to insure its protection (White et al. 2014). Barlow (2001) reported that a population of Tiger Spiketail in New Jersey was rapidly declining due to the removal of the surrounding forest canopy. Boda et al. (2015b:556) found that for C. heros Theischinger (Balkan Goldenring), vegetation composition and complexity appears to affect emergence behavior and recommended “maintaining riparian forests in near pristine condition.” This conservation strategy is likely also appropriate for Tiger Spiketail. Habitats where Tiger Spiketail are found are expected to be highly sensitive to disturbance given their headwaters location, spring-fed hydrology, and occurrence in large, mature forest tracts. These factors suggest large riparian buffers and entire drainage-basin protection may be needed to maintain habitat suitability. Trees along breeding streams appear to be a critical habitat component, as we observed that sites where Tiger Spiketail emerged were commonly on trunks away from the water. Emergence sites on trees away from the water appear to be broadly shared by other Cordulegaster species in North America and Europe and have been reported for Pacific Spiketail in California (Kennedy 1917); Cordulegaster bilineata Carle (Brown Spiketail) in Tennessee, Twin-spotted Spiketail (location not reported), Cordulegaster obliqua Say (Arrowhead Spiketail) in Wisconsin, and Cordulegaster sp. in Quebec (as reported in Glotzhober 2006); C. boltonii Donovan (Golden-ringed Dragonfly) in Germany (Cordero-Rivera and Stoks 2008); and Balkan Goldenring and C. bidentata Selys (Sombre Goldenring) in Germany (Müller 2000). Various reasons have been proposed for emergence sites high above the ground including high nymph densities (Bennett and Mill 1993, Corbet 1957), predation threats (Coppa 1991, Miller 1964), competition for emergence sites (Cordero 1995), and flood avoidance (Worthen 2010). As with many other life-history aspects of Tiger Spiketail, further work is needed to understand emergence-site selection. We easily found Tiger Spiketail exuviae along the breeding streams, and therefore it seems such surveys can provide an effective, non-invasive survey methodology for identifying habitats when the adults are not present. Exuvial collections have provided reliable estimates of nymphal density and habitat quality for other endangered dragonflies (e.g., Foster and Soluk 2004). Exuvial studies may also provide a survey method that does not impact nymphal populations (Raebel et al. 2010). In our study, the head width and encrusted nature of Tiger Spiketail exuviae and size of the nymphs in October and April indicate that Tiger Spiketail winter diapause in multiple instars. Based on exuvial collections, emergence is largely during late June and July with long adult longevity resulting in a prolonged flight period. Fifty-eight percent (14/24) of the exuvia were lightly encrusted and 29% (7/24) were heavily encrusted. Only 3 (12%) of the exuvia were not encrusted, Northeastern Naturalist 150 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 1 (4%) of which was heavily stained. Encrusted exuviae have been reported by Ferreras-Romero and Corbet (1999) for Golden-ringed Dragonfly and by Ferreras- Romero (1997) for Boyeria irene Fonscolombe (Western Spectre) in Spain. Those authors suggested that encrusted and non-encrusted exuviae reflect partivoltine and semi-voltine emergence, respectively, as a result of the length of time submerged in the sediments for the last instar. Paulson and Jenner (1971) found in North Carolina that Twin-spotted Spiketail exhibited a short, synchronized emergence with overwintering in all the larger instars. They suggested that this phenomenon reflects the long development time of the nymph and may be a characteristic of all large odonates living in waters with low temperatures. An overlap of cohorts from a long nymphal period has also been reported for Tiger Spiketail in Ohio (Glotzhober 2006), Delta-spotted Spiketail and Twin-spotted Spiketail in New York (Hager et al. 2012), Golden-ringed Dragonfly in Spain (Ferreras- Romero and Corbet 1999), Balkan Goldenring and Sombre Goldenring in Austria (Lang et al. 2001), and possibly C. dorsalis in British Columbia, Canada (Marczak et al. 2006). Larval densities in our study (0.112 individuals m-2 in spring and 0.086 individuals m-2 in fall) were lower than those reported for Tiger Spiketail in Ohio (1.25–1.43 nymphs per linear meter; Glotzhober 2006). Larval densities for other Cordulegaster species have also been reported. Lang et al. (2001) found 0.41 nymphs per linear meter for Sombre Goldenring and 0.78 nymphs per linear meter for Balkan Goldenring in Austria. We suggest that combining a suite of biotic and abiotic habitat characteristics may increase the predictive quality of Tiger Spiketail habitat models and aid conservation planning for this rare species. In our study, we detected Tiger Spiketail adults, nymphs, and exuviae in a pair of fish-free, perennial headwater streams (spring- and seepage-fed) flowing through large areas of mature forest. We rarely encountered other odonates on the streams. We also found Tiger Spiketail exuviae at 3 other streams in New Jersey, Connecticut, and Delaware. Two predictive habitat models have been developed for Tiger Spiketail but the authors of both suggested refinements are necessary (Howard and Schlesinger 2012, Winkler et al. 2008). In New Jersey, the Endangered and Non-Game Species Program has developed a landscape project habitat-predictive model for Tiger Spiketail, but noted “Insufficient information exists in the scientific literature to support the designation of an occurrence area” (Winkler et al. 2008:232). In New York, an element distribution model for Tiger Spiketail was developed that identifies the 8 most important variables for potential habitat as topography, presence of water, slope, surficial geology, bedrock geologic class, percent shrub cover, percent wetland cover, and May precipitation (Howard and Schlesinger 2012). However, the predictive nature of this model for finding new Tiger Spiketail sites is only rated as fair (Howard and Schlesinger 2012). The limitations of the New Jersey and New York models noted by their authors suggest that a better understanding of the nymphal habitats may be useful for refining the existing models. In Germany, Tamm (2012) found that geology can be strongly predictive for Sombre Goldenring and utilized for easily identifying nymphal and adult habitats. Given the Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 151 apparent similarity of Tiger Spiketail habitats across its range, testing geologic mapping as a predictive factor seems warranted. Based on our study, other factors not identified in the existing predictive models may be useful for refining habitat evaluations, including spring- and seepage-fed hydrology, continual flow during prolonged drought, location in the uppermost reaches of a drainage basin, the absence of fish, and having a depauperate odonate fauna. We hope our study will add to the identification and protection of this charismatic and highly vulnerable species. Acknowledgments We thank Dr. George Hamilton, Dr. Mark Robson, Dr. Martin Wikelski, 4 anonymous reviewers, and Joshua Ness, the manuscript editor, for their reviews of the manuscript and EcolSciences, Inc. for the time and resources to conduct this study. Literature Cited Bangma, J. 2006. NJODES: The dragonflies and damselflies of New Jersey: Tiger Spiketail species profile. Available online at http://www.njodes.com/Speciesaccts/spiketails/spiktige. asp. Accessed 30 June 2015. Barlow, A. 1995. On the status of Cordulegaster erronea Hagen in Selys, 1878 in the State of New Jersey. Argia 7:6–9. Barlow, A. 2001. Second annual report of the New Jersey Odonata survey including a state record and numerous county records. Argia 13:1–32. Bennett, S., and P. Mill. 1993. Nymph development and emergence of Pyrrhosoma nymphula (Sulzer) (Zygoptera: Coenagrionidae). Odonatologica 22:133–145. Boda, R., C. Bereczki, B. Pernecker, P. Mauchart, and Z. Csabai. 2015a. Life history and multiscale habitat preferences of the red-listed Balkan Goldenring, Cordulegaster heros Theischinger, 1979 (Insecta, Odonata), in South-Hungarian headwaters: Does the species have mesohabitat-mediated microdistribution? Hydrobiologia 760:121–132. Boda, R., C. Bereczki, A. Ortmann-Ajkai, P. Mauchart, B. Pernecker, and Z. Csabai. 2015b. Emergence behavior of the red-listed Balkan Goldenring (Cordulegaster heros Theischinger, 1979) in Hungarian upstreams: Vegetation structure affects the last steps of the nymph. Journal of Insect Conservation 19:547–557. Burcher, C., and L. Smock. 2002. Habitat distribution, dietary composition, and life-history characteristics of odonate nymphs in a blackwater coastal-plain stream. American Midland Naturalist 148:75–89. Coppa, G. 1991. Notes sur l’émergence d’ (Charpentier) (Odonata: Cordudliidae). Martinia 7:7–16. Corbet, P. 1957. The life history of the Emperor Dragonfly, Anax imperator Leach (Odonata: Aeshnidae). Journal of Animal Ecology 26:1–69. Corbet, P. 1999. Dragonflies: Behavior and Ecology of Odonata. Cornell University Press, Ithaca, NY. 829 pp. Corbet, P., F. Suhling, and D. Soendgerath. 2006. Voltinism of Odonata: A review. International Journal of Odonatology 9:1–44. Cordero, A. 1995. Vertical stratification during emergence in odonates. Notulae Odontologicae 4:103–105. Northeastern Naturalist 152 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 Cordero-Rivera, A., and R. Stoks. 2008. Mark–recapture studies and demography. Pp. 7–20, In A Córdoba-Aguilar (Ed.). Dragonflies and Damselflies: Model Organisms for Ecological and Evolutionary Research. Oxford University Press, Oxford, UK. Cordoba-Aguilar, A. (Ed.). 2008. Dragonflies and Damselflies: Model Organisms for Ecological and Evolutionary Research. Oxford University Press, Oxf ord, UK. 304 pp. Eby, C. 1976. Soil survey of Morris County, New Jersey. US Department of Agriculture, Soil Conservation Service, 1976 – 213-856/62. US Government Printing Office, Washington, DC. 111 pp. Ferreras-Romero, M. 1997. The life history of Boyeria irene (Fonscolombe, 1838) (Odonata: Aeshnidae) in Sierra Morena Mountains (southern Spain). Hydrobiologia 345:109–116. Ferreras-Romero, M., and P. Corbet. 1999. The life cycle of Cordulegaster boltonii (Donovan, 1807) (Odonata: Cordulegastridae) in the Sierra Morena Mountains (southern Spain). Hydrobiologia 405:39–48. Foster, S., and D. Soluk. 2004. Evaluating exuvia collection as a management tool for the federally endangered Hine’s Emerald Dragonfly, Somatochlora hineana Williamson (Odonata: Cordulidae). Biological Conservation 118:15–20. Glotzhober, B. 2006. Life-history studies of Cordulegaster erronea Hagen (Odonata: Cordulegastridae) in the laboratory and the field. Bulletin of American Odonatology 10:1–18. Hager, B., N. Kalantari, and V. Scholten. 2012. The distribution of Cordulegaster (Odonata: Cordulegastridae) nymphs in seeps and springs of Nelson Swamp (Madison County, NY). Northeastern Naturalist 19 (Special Issue 6):67–76. Howard, T., and M. Schlesinger. 2012. PATHWAYS: Wildlife-habitat connectivity in the changing climate of the Hudson Valley. New York Natural Heritage Program, Albany, New York. Available online at http://nynhp.org/files/pways/NYNHP_2012_PATHWAYS_ final_report.pdf. Accessed 30 January 2017. International Union for the Conservation of Nature (IUCN). 2015. The IUCN red list of Threatened Species. Version 2015-3. Available online at http://www.iucnredlist.org/ details/165498/0. Accessed 9 September 2015. Kennedy, C. 1917. Notes on the life history and ecology of the dragonflies (Odonata) of central California and Nevada. Proceedings of the US National Museum 52:483–635. Lang, C., H. Mueller, and J. Waringer. 2001. Nymph habitats and longitudinal distribution patterns of Cordulegaster heros Theischinger and C. bidentata Selys in an Austrian forest stream (Anisoptera: Cordulegastridae), Odonatologica 30:395–409. Liebelt, R., M. Lohr, and B. Beinlich. 2010/2011. Zur Verbreitung der Gestreiften und Zweigestreiften Quelljungfer (Cordulegaster bidentata und C. boltonii) im Kreis Höxter (Insecta, Odonata, Cordulegastridae). Beiträge zur Naturkunde zwischen Egge und Weser 22:3–18. Marczak, L., J. Richardson, and M. Classen. 2006. Life-history phenology and sedimentsize association of the dragonfly Cordulegaster dorsalis (Odonata: Cordulegastridae) in an ephemeral habitat in southwestern British Columbia. The Canadian Field Naturalist 120:347–350. May, M., and F. Carle. 1996. An annotated list of the Odonata of New Jersey. Bulletin of American Odonatology 4:1–35. Miller, P. 1964. Notes on Ictinogomphus ferox Rambur (Odonata: Gomphidae). Entomologist 97:52–66. Moskowitz, D., and M.L. May. 2017. Adult Tiger Spiketail (Cordulegaster erronea Hagen) habitat use and home range observed via radio-telemetry with conservation recommendations. Journal of Insect Conservation 21:885–895. Northeastern Naturalist Vol. 26, No. 1 D. Moskowitz and M.L. May 2019 153 Müller, H. 2000. Untersuchungen zu Cordulegaster heros Theischinger, 1979 und C. bidentata Selys, 1843 Teil I: Imagines. Anax 3:19–22. Müller, L., and J. Waringer. 2001. Larval habitats and longitudinal distribution patterns of Cordulegaster heros Theischinger and C. bidentata Sélys in an Austrian forest stream (Anisoptera: Cordulegastridae). Odonatologica 30:395–409. National Weather Service. 2019. Preceipitation departures. Available online at https://www. weather.gov/marfc/Precipitation_Departures. Accessed on 24 January 2019. NatureServe. 2015. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. Cordulegaster erronea. NatureServe, Arlington, VA. Available online at http://www.natureserve.org/explorer. Accessed 5 December 2012. Needham, J., M. Westfall Jr., and M. May. 2000. Dragonflies of North America, revised edition. Scientific Publishers, Gainesville, FL. 939 pp. New Jersey Department of Environmental Protection (NJDEP). 2019. DataMiner. Available online at http://www.nj.gov/dep/opra/online.html. Accessed 24 January 2019. NJDEP/New Jersey Geological Survey (NJGS). 1999. Bedrock Geology for New Jersey 1:100,000 Scale. Available online at http://www.state.nj.us/dep/njgs/geodata/dgs07-2. htm. Accessed 30 January 2017. NJDEP/NJGS. 2006. Surficial Geology of New Jersey. Available online at http://www.state. nj.us/dep/njgs/geodata/njsrfgeo.htm. Accessed 30 January 2017. New York Natural Heritage Program (NYNHP). 2012. Tiger Spiketail (Cordulegaster erronea). Species accounts, distributional maps, and phenology charts. New York Natural Heritage Program (NYNHP). Element-distribution model, model variation, and environmental variable importance for Cordulegaster erronea. Albany, NY Available online at http://www.dec.ny.gov/docs/fish_marine_pdf/nyddsfinalreportpt7.pdf. Accessed 5 December 2012. Olcott, S. 2011. Final Report for the West Virginia Dragonfly and Damselfly Atlas West Virginia Division of Natural Resources, Wildlife Resources Section. Available online at http://www.wvdnr.gov/publications/PDFFiles/OdenateAtlasReportweb.pdf. Accessed 30 January 2017. Paulson, D., and C. Jenner. 1971. Population structure in overwintering nymph odonata in North Carolina in relation to adult flight season. Ecology 52:96 –107. Raebel, E., T. Merckx, P. Riordan, D. Macdonald, and D. Thompson. 2010. The dragonfly delusion: Why it is essential to sample exuviae to avoid biased surveys. Journal of Insect Conservation 14:523–533. Robichaud, B., and M. Buell. 1983. Vegetation of New Jersey. Rutgers University Press, New Brunswick, NJ. 340 pp. Stevenson, D., G. Beaton, and M. Elliott. 2009. Distribution, status, and ecology of Cordulegaster sayi Selys in Georgia, USA (Odonata: Cordulegastridae). Bulletin of American Odonatology 11:20–25. Suhonen, J., M.J. Rantala, and J. Honkavaara. 2008. Territoriality in odonates. Pp. 203–217, In A. Córdoba Aguilar (Ed.). Dragonflies and Damselflies: Model Organisms for Ecological and Evolutionary Research. Oxford University Press, Oxf ord, UK. 304 pp. Tamm, J. 2012. Cordulegaster bidentata in Hessen mit besonderer Berücksichtigung ihrer Bindung an den geologischen Untergrund (Odonata: Cordulegastridae). Libellula 31:131–154. Trottier, R. 1973. Influence of temperature and humidity on the emergence behavior of Anax junius (Odonata: Aeshnidae). The Canadian Entomologist 105:975–984. US Census Bureau (USCB). 2019. Quick facts: New Jersey. Available online at https:// www.census.gov/quickfacts/nj. Accessed 24 January 2019. Northeastern Naturalist 154 D. Moskowitz and M.L. May 2019 Vol. 26, No. 1 US Department of Agriculture, Natural Resources Conservation Service (USDA NRCS). 2008. Soil survey geographic 2008 (SSURGO) database for Morris County, New Jersey (Projected to NJ State Plane Feet, NAD83). Version 20080818. Available online at http://www.nj.gov/dep/gis/digidownload/metadata/soil/mor_ssurgo.htm. Accessed 30 January 2017. White, E., P. Hunt, M. Schlesinger, J. Corser, and P. deMaynadier. 2014. A conservationstatus assessment of Odonata for the northeastern United States. New York Natural Heritage Program, Albany, NY. Available online at http://rcngrants.org/sites/default/ files/final_reports/RCN%202011-3%20final%20report.pdf. Accessed 30 January 2017. Winkler, P., G. Fowles, M. Valent, and P. Woerner. 2008. New Jersey’s landscape project (Version 3.0 Highlands): A species-based patch approach to rare and imperiled wildlife habitat-mapping for community land-use planning and species conservation. New Jersey Department of Environmental Protection, Division of Fish and Wildlife, Endangered and Nongame Species Program. Available online at http://www.state.nj.us/dep/fgw/ ensp/landscape/lp_report_3_0.pdf. Accessed 30 January 2017. Worthen, W. 2010. Emergence-site selection by the dragonfly Epitheca spinosa (Hagen). Southeastern Naturalist 9:251–258.