Status and conservation of an imperiled tiger beetle fauna in New York State, USA

Abstract

New York has 22 documented species of tiger beetles (Coleoptera: Cicindelidae). Over half of these species are considered rare, at risk, or potentially extirpated from the state. These rare species specialize on three sandy habitat types under threat from human disturbance: beaches, pine barrens, and riparian cobble bars. In 2005, we began a status assessment of eight of New York’s rarest tiger beetles, examining museum records, searching the literature, and conducting over 130 field surveys of historical and new locations. Significant findings included (1) no detections of four of the eight taxa; (2) no vehicle-free beach habitat suitable for reintroducing Cicindela dorsalis dorsalis; (3) C. hirticollis at only 4 of 26 historical locations; (4) C. patruela patruela at only one site statewide; and (5) C. ancocisconensis at only 3 of 28 de novo survey sites. Additional species that might be declining deserve our attention, as do some threats to tiger beetle habitats, like lack of beach wilderness, fire suppression in pine barrens, and river damming. Rarity in tiger beetles is a result of varying ecologies, which suggest different conservation strategies. Future inventory and documentation of tiger beetle occurrences need to take into account the metapopulation structure and imperfect detectability of these rare insects.

Appendix: Definitions of natural heritage global and state ranks (adapted from NatureServe 2010)

Global and state status ranks

The New York Natural Heritage Program’s statewide inventory efforts revolve around lists of rare species and all types of natural communities known to occur, or to have historically occurred, in the state. These lists are based on a variety of sources including museum collections, scientific literature, information from state and local government agencies, regional and local experts, and data from neighboring states.

Each rare species is assigned a rank based on its rarity and vulnerability. Like that in all state Natural Heritage Programs, NY Natural Heritage’s ranking system assesses rarity at two geographic scales: global and state. The global rarity rank reflects the status of a species or community throughout its range, whereas the state rarity rank indicates its status within New York. Global ranks are maintained and updated by NatureServe, which coordinates the network of Natural Heritage programs. Both global and state ranks are usually based on the range of the species or community, the number of occurrences, the viability of the occurrences, and the vulnerability of the species or community around the globe or across the state. As new data become available, the ranks may be revised to reflect the most current information. Subspecific taxa are also assigned a taxon rank which indicates the subspecies’ rarity rank throughout its range.

For the most part, global and state ranks follow a straightforward scale of 1 (rarest/most imperiled) to 5 (common/secure), as follows. Translation to IUCN categories (Master et al. 2009) is noted.

GX, SX—Presumed Extinct or Extirpated

Not located despite intensive searches of historical sites and other appropriate habitat, and virtually no likelihood that it will be rediscovered (IUCN: Extinct, Extinct in the Wild, Regionally Extinct).

GH, SH—Possibly Extinct

Known from only historical occurrences but still some hope of rediscovery. There is evidence that the species may be extinct throughout its range or extirpated from the state, but not enough to state this with certainty (IUCN: Critically Endangered).

G1, S1—Critically Imperiled

At very high risk of extinction or extirpation due to extreme rarity (often 5 or fewer populations), very steep declines, or other factors (IUCN: Critically Endangered, Endangered).

G2, S2—Imperiled

At high risk of extinction or extirpation due to very restricted range, very few populations, steep declines, or other factors (IUCN: Vulnerable).

G3, S3—Vulnerable

At moderate risk of extinction or extirpation due to a restricted range, relatively few populations, recent and widespread declines, or other factors (IUCN: Near Threatened).

G4, S4—Apparently Secure

Uncommon but not rare; some cause for long-term concern due to declines or other factors (IUCN: Least Concern).

G5, S5—Secure

Common; widespread and abundant (IUCN: Least Concern).

GU, SU—Unrankable

Currently unrankable due to lack of information or due to substantially conflicting information about status or trends (IUCN: Data Deficient).

SNA—Not Applicable

A conservation status rank is not applicable because the species or ecosystem is not a suitable target for conservation activities. Examples include a visitor to the state but not a regular occupant (such as a bird or insect migrating through the state), or a species that is predicted to occur in the state but that has not been found.

Note that combination (or “range”) ranks are possible (e.g., S1S2, S2S3). These ranks reflect uncertainty in the information available such that it could not be determined whether one or the other rank was appropriate. They do not indicate a value in between the two numbers.