STATUS OF THE SPECIES RANGEWIDE

Northeastern beach tiger beetle (Cicindela dorsalis dorsalis)(NBTB)

 

Species Description and Life History –NBTB has been listed as a threatened species under the ESA since August 7, 1990 (Service 1990).  It is a beach-dwelling insect measuring approximately 0.5 inch in length, from the family Cicindelidae.  It has white to light tan wing covers, often with several fine grayish-green lines, and a bronze-green head and thorax (Service 1994). 

 

Adult NBTBs are active, diurnal surface predators.  They forage along the water's edge on small amphipods, flies, and other beach arthropods, or scavenge on dead amphipods, crabs, and fish (Knisley et al. 1987, Service 1994).  Most foraging occurs in the damp sand of the intertidal zone and scavenging has been observed to occur more often than predation (Knisley et al. 1987).  Adult NBTBs are present on beaches from early June through early September, and spend most of the day along the water’s edge (Knisley et al. 1987).  Adults are active on warm, sunny days when they can be seen feeding, mating, or basking (Service 1994).  They are less active on rainy, cool, or cloudy days because they cannot maintain their body temperature (C.B. Knisley, pers. comm. 1994).  They rely on a variety of behaviors, such as foraging and basking, to maintain their high body temperatures (Knisley et al. 1987).

 

Adult NBTBs mate and lay eggs on the beach during the summer (starting in June and ending by mid July).  Eggs are deposited near the sand surface or in shallow pits excavated by adults, usually within 1 inch of the beach surface (Knisley 1997b).  The eggs hatch in 10-14 days, depending on soil moisture.  Adequate moisture may allow a shorter hatch period (C.B. Knisley, pers. comm. 2008).  Larvae pass through three instar stages, pupate, and emerge as adults two years following hatching (Knisley et al. 1987, Service 1994).  However, some larvae that hatch early and find sufficient food may develop more rapidly and emerge as adults after only one year (Service 1994).  Development through three larval stages and pupation takes place within a larval burrow (Knisley et al. 1987).  First instars generally occur from late August through September, second instars from September to late fall, and third instars from late fall to early spring and through the second year (Knisley et al. 1987).

 

Knisley et al. (1987) found that the distribution of first and second instars was similar and highest densities of third instars were on the beach in the mid- to upper-tidal zone.  Therefore, most burrows were underwater during high tide.  Larvae can survive flooding for 3-6 days (Service 1994).  Larval burrow depths ranged from 3.5-9.5 inches and increased with distance from the water’s edge, suggesting that burrow depth may be related to subsurface moisture (Knisley et al. 1987).  Knisley (1997b) found that larvae rarely occur on sites with less than 5 degrees slope.  Larvae typically occur in an area of beach 26-39 feet (ft) wide, but have been documented at narrower widths, within and above the intertidal zone.  Areas wider than 39 ft where washover has occurred or where the upper beach is flat and periodically inundated by high tides also are occasionally occupied by larvae (Service 1994).

 

Larval activity is highly variable and greatly influenced by temperature, substrate moisture, tide levels, and season (Service 1994).  They overwinter in their burrows until mid-March, with low levels of activity when the sand is damp and cool (C.B. Knisley, pers. comm. 1994).  The highest, most predictable periods of larval activity are from late August through early November. Active primarily at night, larvae plug their burrows during most of the daylight hours.  They have been found crawling on the beach, apparently moving to dig a new burrow in a better location (Service 1994).  This behavior is likely a response to variations in tide levels, soil moisture, or sand accretion and erosion patterns.  Larvae lack a hard cuticle and are susceptible to desiccation, which may explain why they tend to become inactive during hot, dry conditions (Service 1994).  Generally, larval burrows are plugged and not visible when the sand is dry and warm. 

Larvae feed by ambushing passing prey.  Little is known about the precise types of microarthropods eaten by NBTB larvae, but prey that have been identified include beach fleas, lice, flies, ants, and other small insects (Pearson et. al. 2006, Knisley 2008).  While little information on the necessary prey abundance is known, lack of prey base may explain why NBTBs are not found in certain areas. 

    

Knisley et al. (1987) found that first emergence of adults ranged from June 5-13 in Virginia.  Rainfall appears to enhance emergence since numbers of adults usually increase after a rainfall.  The number of adult NBTBs increase rapidly in June, peaks in mid-July, begins to decline through August, and few adults can be found in September.  There is a period of approximately two weeks after adults emerge when there is little to no dispersal (Hill and Knisley 1994).  Then, a small number of adult NBTBs disperse to other sites.  After peak numbers emerge in early July (Knisley and Hill 1989; Service 1994), there is a regular dispersal phase.  Mark-recapture studies have determined that adult NBTBs may travel 5-12 miles (mi) (Knisley and Hill 1989) from sites where they were marked, and some individuals may disperse up to 15 mi (Knisley 1997a).  In Northumberland County, Virginia a total of 10,131 adult NBTBs were marked and released; 91 NBTBs dispersed to new sites (mainly between two close, large sites 1 mi apart) (Hill and Knisley 1994).  Large sites seem to serve as recruitment areas, while small sites serve as stop-overs during dispersal (Hill and Knisley 1994).  “It is probable that feeding or resting occur at these smaller sites and that without them, the larger sites may not experience as much migration” (Hill and Knisley 1994).  This dispersal serves to exchange genetic material, allow for the colonization of unoccupied sites, and enable NBTBs to leave eroding sites (Hill and Knisley 1994).

 

Survey data from 1998-2002 (Knisley and Hill 1998, 1999; Knisley 2001; Knisley 2002) indicate that beaches with a length of at least 325 ft, a width of at least 6.5 ft, and an adult population of at least 30, serve as breeding sites and larvae should be considered present.  Optimal NBTB habitat is a beach greater than 16-26 ft wide (C.B. Knisley, pers. comm. 1994).  Preference for beaches with a width of 8-20 ft was found to be statistically significant, and NBTBs are rarely found on beaches less than 6.5 ft in width (Drummond 2002).  Adult and larval NBTBs are typically found on highly dynamic beaches with back beach vegetation, and they prefer long, wide beaches that have low human and vehicular activity, fine sand particle size, and a high degree of exposure (Knisley et al. 1987).  Although narrow beach width is frequently the reason for lack of larvae, there are instances where larvae have variable densities or are absent on wide beaches. 

 

Preliminary work indicates a correlation between the extent of shallow water fronting the beach and the number of NBTBs present (the more sand bars, the more NBTBs) (Drummond 2002).  A beetle with sedentary larvae is susceptible to wave impacts, and work by Rosen (1980) has shown that the greater the shallow zone fronting a beach, the lower the wave energy.  There appears to be no beach aspect preference for NBTB (Drummond 2002). 

 

Limited studies have been conducted to define the sand characteristics at sites where NBTBs currently occur, and further studies are needed to accurately identify the sand characteristics that NBTBs need to support all life stages.  Knisley (1997b) found that larval densities were highly variable relative to sand particle size, and that larvae are rare at sites with greater than 60% coarse sand (defined as the percentage of sand particles too large to sieve through the 100-size mesh sieve) (Knisley 1997b).  Drummond (2002) found that adult NBTBs occupied beaches with 40-80% coarse sand.  If the sand size is too coarse, too fine, or contains a high organic content, it appears unsuitable for the larvae to burrow and maintain a larval tube.  Preliminary data indicate that NBTB is found on beaches with a narrow range of bulk density ranging from 1.30-1.59 ounces/inch3 (Drummond 2002).  Bulk density may impact NBTB distribution in two ways:  (1) stability of larval burrows, and (2) prey base availability (Drummond 2002).  Bulk density affects microarthropod abundance and type (Blair et al. 1994).  During a study of two beach nourishment projects, Fenster et al. (2006) found that NBTB prefers beaches with sands having a mean grain size of 0.0196 to 0.236 inches, and with relatively compacted sediment.  Mean grain size and sediment compaction are biologically important factors during oviposition and burrow building.  Females oviposit in particular sediment types based on the shape of their ovipositor (Fenster et al. 2006).  Larvae require sediments that they can build burrows in that do not collapse (Fenster et al. 2006).

 

Population Dynamics – Populations of NBTBs are highly variable from year to year because they are subject to local extirpations from storm events impacting the larval stage and are affected by dispersal and recolonization movements (Service 1994).  Two- to three-fold year-to-year variation in numbers at a given site is common (Knisley and Hill 1989, 1990).  The Service funded a PVA for the Chesapeake Bay populations of NBTB, to compare management strategies, not to estimate extinction probabilities, per se (Gowan and Knisley 2001).  The PVA compared six management strategies and found that without increased protection of the most important NBTB populations, the extinction probability throughout its range over the next century is high (Gowan and Knisley 2001).  To reduce extinction risk, the PVA concluded that protection of 25-50 NBTB subpopulations throughout the Chesapeake Bay is necessary (Gowan and Knisley 2001).  The difficulty lies in selecting sites that assure adequate geographic coverage (Gowan and Knisley 2001).

 

NBTBs in the Chesapeake Bay and Massachusetts are currently physically and genetically isolated from each other.  Vogler et al. (1993b) examined genetic variation in these populations.  They found that the isolated Martha’s Vineyard population and Chesapeake Bay populations had low genetic variability.  “The Martha’s Vineyard population can be further distinguished by the presence of an allozyme allele . . . that has not been observed in the Chesapeake Bay NBTBs” (Service 1994).  “Thus, although populations from these two areas represent the same subspecies, they should be considered as separate conservation units (Vogler and DeSalle 1994)” (Service 1994).  Additional genetic work supports treating the Massachusetts population as a distinct group from the Chesapeake Bay populations with regards to species recovery and management (Vogler and Goldstein 1997).

 

Rangewide Status – Historically, NBTB was a common inhabitant of coastal beaches from Cape Cod, Massachusetts to central New Jersey, and along the Chesapeake Bay, from Calvert County, Maryland south through Virginia.  To facilitate the re-establishment of the species across its former range, the NBTB’s recovery plan established nine Geographic Recovery Areas (GRAs) to provide a framework within which protection and population efforts could be ranked and implemented (Service 1994).  Table 1 provides a summary of the status of each GRA.

 

There are two naturally occurring NBTB metapopulations in Massachusetts, one at Martha's Vineyard (GRA 1) (comprised of three sites) and one near Westport (comprised of a single site).  Survey work documented the highest number of adult NBTBs observed at Martha’s Vineyard as 3,388 in 2005, and since that time the following numbers have been documented:  1,261 in 2006, 1,196 in 2007, 1,629 in 2008, 1,513 in 2009, 3,072 in 2010, and 1,503 in 2011 (T. Simmons, Massachusetts Division of Fisheries and Wildlife, pers. comm. 2012).  Surveys in 2010 and 2011 found the overall numbers at Martha’s Vineyard stable.  However, at the Squibnocket site on Martha’s Vineyard, storm events after the 2010 survey removed extensive overwash areas dropping the numbers from 1,500 to 93 in 2011 (Simmons, pers. comm. 2012).  The Westport population was discovered in 1994 (152 adults observed) but declined to 10 adults in 1995 and to 2 adults in 2001.  NBTB has not been seen at the Westport site since 2001 and is likely extirpated (S. von Oettingen, Service, pers. comm. 2001, 2008).

 

A third population was established in Massachusetts by translocation of larvae from Martha’s Vineyard to Monomoy National Wildlife Refuge (Nothnagle 2001).  Translocations were conducted from 2000 to 2003 (Davis 2007).  Adult NBTB surveys at this site have shown a steady increase in numbers.  In 2004, 26 adult NBTBs were counted, 16 in 2005, 75 in 2006, 19 in 2007, 180 in 2008, 102 in 2009, 571 in 2010, and 375 in 2011 (Kapitulik 2011).  It is estimated that at peak season, the number of adult NBTBs present at the site was over 1,000 in 2010 and over 800 in 2011 (Kapitulik 2011).

In 1990 when NBTB was listed (55 FR 32088), it was considered extirpated from (GRA 2 and 3) Rhode Island (RI), Connecticut (CT), and New York (Long Island), and is still considered extirpated in these states. 

 

In 1994, larvae collected from multiple sites in Virginia were released at two sites on Sandy Hook, New Jersey (GRA 4), in the National Park Service’s Gateway National Recreation Area.  In summer 1995, adults were documented at both sites, and mating and foraging were observed (A. Scherer, Service, pers. comm. 1996).  In autumn 1995, first instar larvae were documented; a result of reproduction from the reintroduced NBTBs.  During autumn 1995, 367 additional larvae from Virginia were translocated (Knisley et al. 2001).  Shortly after that translocation and the subsequent winter of 1995 and 1996, severe erosion occurred and some NBTB sites were completely eroded.  In 1996, only limited larval activity was detected and no further reintroduction took place.  In spring 1997, 486 larvae from the Chesapeake Bay were released at Sandy Hook and during that summer, 178 adults were documented (Knisley et al. 2001).  In April 1999, 585 larvae were translocated, and 260 adults were counted in July (Knisley et al. 2001).  In 2000, 554 larvae were translocated in April, and 720 adults were counted in July (Knisley et al. 2001).  The population increased to 749 adults in 2001, but the adult numbers dropped to 142 in 2002, 50 in 2003, and 2 in 2005 (Scherer, pers. comm. 2004, 2008).  In 2006, an additional 480 larvae were released at Sandy Hook and 28 adults were observed in July.  Only 2 adults were observed in the reintroduction area in 2007 (National Park Service 2007).  The National Park Service conducted a limited survey in 2008, 7 adults were observed (A. Gluckstein, National Park Service, pers. comm. 2009).  A survey in 2009 found no NBTBs at this site (Scherer, pers. comm. 2009).

 

NBTB populations in Maryland have declined and many of the occupied sites show a trend toward extirpation (C.B. Knisley, pers. comm. 2008).  Between 1988 and 1993, NBTB was documented at 10 sites in Calvert County, Maryland (GRA 5) (Service 1994).  By 1993, NBTB was in decline at 6 of these 10 sites and in a few years the populations were extirpated (C.B. Knisley, pers. comm. 2008). 

 

From 1993-2009 annual NBTB surveys were conducted at the four largest sites in Calvert County:  Scientific Cliffs, Flag Ponds, Calvert Cliffs, and Western Shores/Calvert Beach (C.B. Knisley, pers. comm. 2008).  Scientific Cliffs supported a sizeable population for over five years but then gradually declined and was extirpated in 2004.  Flag Ponds experienced a severe decline with only 2 adults observed in 2008 and NBTB is now considered extirpated from this site (C.B. Knisley, pers. comm. 2011b).  The Calvert Cliffs site has degraded over the years, and due to limited access, it is uncertain if the population is extirpated.  Currently the only site in Calvert County known to support a viable population is the Western Shores/Calvert Beach site, and NBTB numbers have declined from a high of 4,198 adults in 1991, to 623 in 2005 (Knisley 2005d).  More recent surveys found 589 adults in 2010 and 436 adults in 2011, indicating that the adult numbers held somewhat steady at 400-600 adults for the last 6 years (C.B. Knisley, pers. comm. 2011b). 

 

The two NBTB sites in Maryland outside Calvert County are Cedar and Janes Islands (GRA 6) and have shown steady or increasing numbers.  At Cedar Island 1,095 adults were documented in 2004, 1,298 in 2005, and 1,439 in 2010 (Knisley 2005d; C.B. Knisley, pers. comm. 2011b).  At Janes Island 369 adults were documented in 2004, 2,476 in 2005, and 1,163 in 2010 (Knisley 2005d; C.B. Knisley, pers. comm. 2011b).   

 

In 1999, 2002, 2005, and 2009, comprehensive NBTB adult surveys were conducted along the eastern shoreline of the Chesapeake Bay in Virginia (GRA 7).  The 1999 survey found 32,143 adults (Knisley and Hill 1999), the 2002 survey found 33,469 adults (Knisley 2002), the 2005 survey found 38,498 adults (Knisley 2005c), and the 2009 survey found 46,082 adults (Knisley 2009).  During the 2005 survey a site (Church Neck) was discovered with 2,297 adult NBTBs.  From 2006-2008, surveys of eastern shoreline of the Chesapeake Bay in Virginia were only conducted at sites owned by the VDCR, TNC, and the Service, and indicated relatively stable populations.  The 2009 survey (Knisley 2009) further supported this trend with the highest numbers documented to date.  Overall, the eastern shoreline shows an increase in numbers of adults, but the number of sites occupied is declining (Knisley 2009).

 

In 1998, 2001, 2004, and 2008, NBTB surveys were conducted along the western shoreline of the Chesapeake Bay in Virginia (GRA 8 and 9).  In 1998, 26,685 adults were found (Knisley and Hill 1998).  In 2001, 33,278 adults were found (Knisley et al. 2001).  In 2003, Hurricane Isabel hit the Chesapeake Bay area.  In 2004, the Service completed a survey of the western shoreline to determine what impacts Hurricane Isabel may have had on NBTB (Knisley 2005e).  The 2004 survey found 12,306 adult NBTBs (a 63% decline in numbers from the 2001 surveys).  All NBTBs and habitat were lost at eight sites.  In 2005, a survey of the western shoreline in Virginia found 19,430 adult NBTBs.  The 2005 survey suggested that while NBTBs at a number of sites were recovering slowly, other sites showed no adults present, possibly indicating that all instar stages had been lost during the 2003 hurricane.  In 2006, Hurricane Ernesto made landfall in Virginia.  In 2007, landowners along the Potomac River indicated that Hurricane Ernesto had caused major changes to the shoreline.  The Service (2007) conducted a survey of this area to evaluate the impacts from Hurricane Ernesto to NBTB and found the total number of adult NBTBs at the eight sites along the Potomac River declined from 3,748 in 2005 to 2,747 in 2007 (26.71%).  The 2008 full survey of the western shoreline of the Chesapeake Bay found 9,933 adult NBTBs (approximately 30% of the numbers observed in the 2001 survey) (Service 2008). 

 

In 2009, the Service finalized a 5-year status review of NBTB (Service 2009).  As a result of the continued loss of NBTB populations and habitat and the overall declining population trend described above, the Service recommended reclassifying NBTB from threatened to endangered.  To date, no action has been taken to formally propose reclassification.

 

Table 4.  Summary of the status of NBTB throughout its range.

 

GRA

Location

Status 

Site Specific Comments

1

Coastal Massachusetts and Islands

Stable

·         Westport - population extirpated

·         Martha’s Vineyard - overall numbers appear stable; Squibnocket site from 2010 to 2011 had significant drop of adult NBTBs from 1,500 to 93

·         Monomoy National Wildlife Refuge translocation - numbers increasing

2

Rhode Island

Block Island, RI

Long Island Sound, CT

Extirpated

·         extirpated at time of listing, and to date still considered extirpated

3

Long Island, New York

Extirpated

·         extirpated at time of listing, and to date still considered extirpated

4

Sandy Hook to Little Egg Inlet, New Jersey

Uncertain

·         Sandy Hook translocation - 7 adults observed in 2008, multiple surveys since have located no NBTBs

5

Calvert County, Maryland

Extirpated/

Declining

·         8 sites - extirpated, habitat lost or in poor condition

·         Calvert Cliffs - status uncertain

·         Western Shores/Calvert Beach - declined from high count of 4,198 in 1991 and is holding at 400-600, a 90% decline.

 

6

Tangier Sound, Maryland

Stable/ Increasing

·         Janes Island - ≥ 1,100 adults (protected)

·         Cedar Island - ≥ 1,100 adults (protected)

·         Only GRA that meets delisting criteria (Service 1994)

7

Eastern Shore, Virginia

Stable to declining

·         2009 survey found the highest total count (46,082) of adults since start of comprehensive surveys

·         Increase primarily result of increases at 7 sites (Church Neck North, Occahannock Neck, Silver-Downings Beach, Tankards Beach, Scarborough Neck, Church Neck, Hyslop Marsh)

·         7 sites with no NBTBs compared to 2 in 2005.

·         Significant declines from 2005 occurred at 4 sites (Picketts Harbor, Cape Charles, Elliots Creek South, Kiptopeke), coincidental with increased shoreline modifications or other human impacts

·         Largest decline was at Parkers Marsh (down from 12,554 in 2005, to 1,629 in 2009)

8 & 9

Western Shore, Virginia

Declining

·         Since 2001 a 20% loss in occupied sites (12 of 58 occupied sites) and total numbers declined 70%

·         Habitat loss due to Hurricanes Isabel and Ernesto

·         Since 2001, the 8 largest sites that supported approximately 50% of the total NBTBs declined 78%

·         GRA 8 - 4 occupied sites that support large populations (not protected); 1 “other” sized population Hughlett Point (protected)

·         GRA 9 - 2 occupied sites that support large populations; 1 “other” sized population Bethel Beach

 

Factors Affecting the Species – In 1990, the Service listed NBTB as threatened because of its greatly reduced range and susceptibility to natural and human threats (55 FR 32088).  Natural limiting factors include winter storms, beach erosion, flood tides, hurricanes (Stamatov 1972), and predators.  Anthropogenic threats mentioned in earlier papers included pollution, pesticides, high levels of recreational activity, off-road vehicular traffic, and shoreline alteration (Knisley et al. 1987; Knisley and Hill 1989, 1990; Service 1994).  Past extirpation of NBTB from most of its range has been attributed primarily to destruction and disturbance of natural beach habitat from shoreline development, beach stabilization, and high levels of recreational use (Service 1994).  These threats continue to affect the long-term survivability of NBTB, but with the addition of sea level rise these factors are exacerbated.  Sea levels will change the dynamics that maintain beach habitats, including increased shoreline erosion rates in some areas, and changes in sand deposition (USGS 1998).  The accelerated changes in shoreline structure and composition, and the location of suitable sandy beaches will influence the ability of NBTB to adapt to climate change.

 

Storms impact the coast throughout the year with nor’easters occurring in the winter and hurricanes in the summer/autumn.  Nor’easters affect beach habitats from Massachusetts to Virginia and can cause severe and prolonged flooding and beach erosion.  Hurricanes also can cause significant erosion due to high tides and water levels.  In 2003, Hurricane Isabel impacted NBTB habitat on the western shoreline of Virginia.  Knisley (2005c) determined that the first and second instar larvae from the 2003 adult cohort and the third instars from the 2002 cohort were likely washed out of their burrows by erosion and concluded that the reduced number of adults in 2004 were likely the result of this hurricane.  These storms are natural occurrences that affect NBTB populations, and NBTB’s ability to disperse and recolonize sites, ability to survive prolonged inundation, and other adaptations help their populations persist through these events.  However, with increasing shoreline modification and habitat alteration and sea level rise, the ability of NBTB to withstand and recover from this threat has been reduced.

Erosion within the Chesapeake Bay has occurred for thousands of years from natural sea level rise and wave action.  However, this process has been exacerbated by beach development activities that interfere with natural beach dynamics and longshore sand transport.  Beach stabilization structures such as groins, jetties, rip-rap revetments, and bulkheads, which are designed to reduce erosion, may interrupt and capture sand from longshore transport and build up the beach around the structure but prevent sand from moving to the down-drift shoreline.  Bulkheads and rip-rap typically result in reflection of wave energy onto the forebeach, which ultimately narrows the beach and steepens the profile.  Such changes in the beach profile can occur over periods of 1-30 years.  These structures also prevent the back beach from supplying sand to the forebeach, and concentrate wave energy at the ends of the bulkhead or revetment, resulting in erosion at these points (Knisley 1997a).  “Along a given length of shoreline, the first structure installed often has an adverse impact on the neighbor’s shoreline (usually downstream of a longshore current), thus forcing a sequence of other shoreline modifications.  Eventually, as shoreline modifications increase in number and amount of shoreline modified, the sand ‘bank’ is further depleted as erosion is halted and sand moves offshore into deeper channels.  The long-term (50+ years) impacts of this scenario are unknown, but may eventually lead to a collapse of the natural beach habitat. . .” (Hill and Knisley 1995). 

 

Knisley (1997a) conducted three years (1994-96) of research on the effects of shoreline stabilization structures on the distribution and abundance of NBTB.  A total of 24 sites (51 site sections) were surveyed for adult and larval NBTBs in Virginia.  The sites were placed into one of the following categories:  natural beach (14 sections), narrow beach (6 sections), groins (13 sections), groins/bulkheads (10 sections), and revetments (7 sections).  The mean number of adults and larvae and beach width were greatest at natural beaches.  Natural beaches and those with sand deposition supported the greatest number of larval and adult NBTBs.  Bulkheads and revetments had the greatest negative impact on NBTBs.  “Even though larvae were found at some bulkhead sites and at other modified or narrow sites, they probably have higher winter mortality than those at natural beaches.  Because of a two-year life cycle, larvae are more likely to survive two falls and winters of erosion and beach narrowing when more beach width is available.” (Knisley 1997a).  

 

Monitoring of shoreline stabilization projects since the Knisley (1997a) study continue to show that shoreline hardening generally is detrimental to NBTBs, though there is variability in the responses of habitat and NBTBs depending on other factors, including adjacent beach conditions, project design, and site-specific characteristics.

 

Beach nourishment may be destructive to larvae and may render habitat unsuitable for subsequent larval recruitment and development (Knisley 1991).  However, deposition of dredged material may also create habitat in some cases (Knisley 1997a).  Dredged sand was placed south of Cape Charles in Northampton County, Virginia, in 1987, and the number of adult NBTBs at this site increased from 700-800 to 2,000 in 1993 (Knisley 2002).  Although the addition of sand may maintain the habitat in the long term, it is likely that its immediate effects result in some larval mortality through crushing, smothering, or entombing (Service 1994).  Sand deposition could also have negative effects on food (amphipod) availability (Service 1994).  Fenster et al. (2006) determined that two beach nourishment projects on the western shoreline of the Chesapeake Bay had a short-term positive effect on NBTB habitat.  Within weeks of the sand placement, adults moved in and produced large numbers of larvae at both sites.  The short- and long-term effects of beach nourishment on larvae need to be further investigated. 

 

Non-jeopardy biological opinions anticipating take of NBTBs completed since 1994 have included 12,943 ft of shoreline hardening; 169 groins permanently covering 14,495 ft2 of habitat; 12 piers; and several projects involving breakwaters, beach nourishment, concentrated human use, and unusually large piers and groins.  In addition to permanent loss of habitat, most of the projects have involved additional impacts, including mortality of NBTBs (primarily larvae), during construction.  Fragmentation of NBTB habitat has also resulted from the installation of these structures. 

 

In addition, many shoreline hardening projects (particularly revetments and bulkheads) have been completed that do not require Corps permits and the associated section 7 consultation and biological opinion.  Furthermore, unpermitted activities (i.e., structures built without the required Corps permit) may be contributing to the reduction of NBTB habitat in Virginia as there appears to be more groins and other structures within NBTB habitat than have been permitted (C.B. Knisley, pers. comm. 2004). 

 

Adult foraging, mating, and ovipositing can be disrupted by human activity (Knisley et al. 1987). However, larvae are probably more affected because they spend most of their time at the tops of their burrows waiting for prey, and may be disturbed by even relatively minor activities such as vibrations, movement, and shadows (Knisley et al. 1987).  Knisley and Hill (1990) examined the effects of visitor use of Flag Ponds, a park in Maryland, on NBTB.  As human use increased, no reduction in the population of adult NBTBs was found.  However, human impact appeared to result in the lack of newly emerged adults on the public beach.  Larval survivorship was significantly lower on the beach area with the greatest amount of human use.  Areas that were firmly stomped, to simulate increased foot traffic, resulted in a 50-100% reduction in numbers of active larvae (Knisley and Hill 1989).  In addition, 25% of the burrows did not reopen within 10 days of stomping, suggesting that larvae may have been dead (Knisley and Hill 1989).  Negative effects of foot traffic apparently involve compaction or disruption of burrows or direct injury to larvae.  Because larvae occur in the intertidal zone, burrows can be easily compacted or collapsed by vehicles or high levels of human activity (Knisley et al. 1987). 

 

Primary predators of adult NBTBs are wolf spiders (Arctosa littoralis), asilid flies (C.B. Knisley, pers. comm. 1994), and birds (Service 1994).  The primary larval predator is a small, parasitoid wasp (Methocha sp.) that enters the larval burrow, paralyzes the larva with a sting, and lays an egg on the larvae.  The egg hatches, and as it develops the larval wasp consumes the larval NBTB.  Mites have also been found on larvae at Martha’s Vineyard, but their effect, if any, is unknown (Service 1994).

 

NBTB larvae are probably more vulnerable to habitat disruption than adults (Knisley et al. 1987), and similar to other tiger beetle species, larval survivorship is low due to predators and other limiting factors.  “For example, only about 5% of the first instar larvae of several Arizona species reached adulthood” (Knisley 1987a).  “Habitat disturbances could further reduce survivorship” (Knisley et al. 1987) and “. . . can eliminate suitable habitat (due to shoreline modification), and when combined with natural mortality factors, could reduce populations to the point of extinction” (Knisley 1987a). 

 

Oil slicks and use of pesticides for mosquito control may have contributed to the decline of this species (Stamatov 1972).  Most of the large NBTB populations in Maryland and many of those in Virginia are threatened by activities associated with the increasing human population and all are subject to oil spills and beach erosion (Service 1994). 

 

Literature Cited

 

Blair, J.M., R.W. Parmelee, and R.L. Wyman. 1994. A comparison of the forest floor invertebrate communities of four forest types in northeastern United States. Pedobiologia 38(2):146-160.

 

Davis, C.  2004. Population augmentation of the Puritan tiger beetle, Cicindela puritana through translocation of larvae to Rainbow Beach, Northampton, MA. Report to U.S. Fish and Wildlife Service, Silvio O. Conte National Wildlife Refuge, Turners Falls, Massachusetts.

 

Davis, C. 2007. Monitoring and reintroduction of the northeastern beach tiger beetle, Cicindela dorsalis dorsalis, Monomoy National Wildlife Refuge, 2007. Report to U.S. Fish and Wildlife Service, New England Field Office, Concord, New Hampshire.

 

Drummond, M.R. 2002. The effects of geophysical factors on the distribution of the northeastern beach tiger beetle, Cicindela dorsalis dorsalis Say. Master’s Thesis, Christopher Newport University. 90 p.

 

Fenster, M.S., C.B. Knisley, and C.T. Reed. 2006. Habitat preference and the effects of beach nourishment on the federally threatened northeastern beach tiger beetle. Cicindela dorsalis dorsalis: Western Shore, Chesapeake Bay, Virginia. Journal of Coastal Research 22(5):1133-1144.

 

Gluckstein, A. 2009. Personal communication. U.S. National Park Service, Gateway National Recreation Area, Sandy Hook Unit, New Jersey.

 

Gowan, C. and C.B. Knisley. 2001. A population viability analysis for the northeastern beach tiger beetle in the Chesapeake Bay region. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Gowan, C. and C.B. Knisley. 2005. A population viability analysis for the Puritan tiger beetle in the Chesapeake Bay Region. Report to U.S. Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, Maryland.

 

Gowan, C. and C.B. Knisley. 2010a. Population Viability Analysis for the Puritan tiger beetle in the Chesapeake Bay Region: An Update. Report to U.S. Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, Maryland.

 

Gowan, C. and C.B. Knisley. 2010b. Memorandum of July 15, 2010, providing supplement to the March 2010 Puritan tiger beetle PVA. Report to U.S. Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, Maryland

 

Hill, J.M. and C.B. Knisley. 1991. Current status survey and biological studies of Cicindela dorsalis and C. puritana in Maryland, 1990. Report to Maryland DNR, Natural Heritage Program, Annapolis, MD, and U.S. Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, Maryland.

 

Hill, J.M. and C.B. Knisley. 1994. A metapopulation study of the threatened northeastern beach tiger beetle, Cicindela dorsalis dorsalis in Northumberland County, Virginia. Report to Virginia Department of Conservation and Recreation, Richmond, Virginia.

 

Hill, J.M. and C.B. Knisley. 1995. Distribution and abundance of a biological indicator species, Cicindela dorsalis dorsalis in relation to shoreline structures and modifications. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Kapitulik, N. 2011. Northeastern beach tiger beetle, Cicindela dorsalis dorsalis, monitoring of adults and larvae at Monomoy National Wildlife Refuge and South Beach 2011. Report to U.S. Fish and Wildlife Service, New England Field Office, Concord, New Hampshire.

 

Knisley, C.B. 1987a. Habitats, food resources, and natural enemies of a community of larval Cicindela in southeastern Arizona (Coleoptera: Cicindelidae). Canadian Journal of Zoology 65:1191-1200.

 

Knisley, C.B. 1987b. Status survey of two candidate species of tiger beetles, Cicindela puritana G. Horn and C. dorsalis Say. Report to U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.

 

Knisley, C.B. 1991. Management plan for a population of the threatened tiger beetle, Cicindela dorsalis at Accawmacke Plantation, Virginia. Report to Espey Houston and Company, Austin, Texas.

 

Knisley, C.B. 1994. Personal communication. Randolph-Macon College, Ashland, Virginia.

 

Knisley, C.B. 1997a. Distribution and abundance of the northeastern beach tiger beetle, Cicindela dorsalis dorsalis, in relation to shoreline modifications, in Virginia. Report to Virginia Department of Agriculture and Consumer Affairs, Office of Plant Protection, Richmond, Virginia.

 

Knisley, C.B. 1997b. Microhabitat preferences of Cicindela dorsalis dorsalis, the northeastern beach tiger beetle. Report to Virginia Department of Agriculture and Consumer Services, Richmond, Virginia.

 

Knisley, C.B. 1997c. Monitoring of the northeastern beach tiger beetle, Cicindela d. dorsalis, at Peaceful Beach Estates (O’Leary site) Northampton County, Virginia. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

Knisley, C.B. 2000. Monitoring of the northeastern beach tiger beetle (Cicindela dorsalis dorsalis) along the Shoreline, North of Elliott's Creek, Northampton County, Virginia.  Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2001. A survey of the northeastern beach tiger beetle (Cicindela dorsalis dorsalis) along the western shoreline of the Chesapeake Bay, 2001. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2002. A survey of Cicindela dorsalis dorsalis along the eastern shoreline of the Chesapeake Bay, 2002. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2004. Personal communication. Randolph-Macon College, Ashland, Virginia.

 

Knisley, C.B. 2005a. Monitoring Cicindela puritana and C. dorsalis dorsalis in Maryland, 2004.  Report to Maryland Department of Natural Resources, Annapolis, Maryland.

 

Knisley, C.B. 2005b. Distribution and Abundance of Cicindela puritana and C. dorsalis dorsalis in Maryland, 2005. Report to Maryland D Department of Natural Resources, Annapolis, Maryland.

 

Knisley, C.B. 2005a. A survey of the northeastern beach tiger beetle (Cicindela dorsalis dorsalis) at Eastern Shore of Virginia sites of the Chesapeake Bay, 2005. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2005b. Distribution and abundance of Cicindela puritana and C. dorsalis dorsalis in Maryland, 2005. Report to Maryland Department of Natural Resources, Annapolis, Maryland.

 

Knisley, C.B. 2005c. A survey of the northeastern beach tiger beetle (Cicindela dorsalis dorsalis) at all western and selected eastern shoreline sites of the Chesapeake Bay, 2004. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2005d. A five-year study of the northeastern beach tiger beetle in relation to beach use at Camp Silver Beach (YMCA), Northampton County, Virginia, 2000-2005. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

Knisley, C.B. 2008. Personal communication. Randolph-Macon College, Ashland, Virginia.

 

Knisley, C.B. 2009. A survey of the northeastern beach tiger beetle (Cicindela dorsalis dorsalis) at Eastern Shore of Virginia sites, 2009. Report to U.S. Fish and Wildlife Service, Virginia Field Office, Gloucester, Virginia.

 

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Knisley, C.B. 2011b. Personal communication. Randolph-Macon College, Ashland, Virginia.

 

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Knisley, C.B. and J.M. Hill. 1990. Distribution and abundance of two tiger beetles, Cicindela dorsalis media and C. lepida at Assateague Island, Maryland, 1990. Report to Maryland Department of Natural Resources, Annapolis, Maryland.

 

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