Ecology, distribution, and conservation biology of the tiger beetle Cicindela patruela consentanea dejean (Coleoptera: Carabidae: Cicindelinae)

2007·6.2 MB·

by  Jonathan R Mawdsley

PROC. ENTOMOL. SOC. WASH.
109(1), 2007, pp. 17-28
ECOLOGY, DISTRIBUTION, AND CONSERVATION BIOLOGY OF THE
TIGER BEETLE CICINDELA PATRUELA CONSENTANEA DEJEAN
(COLEOPTERA: CARABIDAE: CICINDELINAE)
Jonathan R. Mawdsley
Department of Entomology, MRC 187, National Museum of Natural History,
Smithsonian Institution, P.O. Box 37012, Washington, DC 20013-7012, U.S.A. (e-
mail: [email protected])
—
Abstract. The tiger beetle Cicindela patruela consentanea Dejean is known only
from the mid-Atlantic coastal plain ofthe United States, where it is closely associated
with pine and oak barrens ecosystems. Historic collecting records document the past
presence of this subspecies at multiple sites in New Jersey and Long Island, while
single specimens are also known from Delaware, Maryland, and Pennsylvania. This
tiger beetle apparently has been extirpated from much ofits former range, and extant
populations are known only from sites within state forests and state wildlife
management areas in the Pine Barrens region of New Jersey. Soil, vegetation, and
forest stand characteristics were studied at four sites occupied by populations of C. p.
consentanea in 2004, 2005, and 2006. Observations on adult biology and population
dynamics are reported. Adult beetles were active along sandy trails and firebreaks in
pine-oak woodlands dominated by Pinus rigida Miller (Pinaceae) and several
Quercus species (Fagaceae), primarily Quercus ilicifolia Wangenheim. The use of
prescribed fire as a forest management tool was evident at three of the four sites.
Management activities which may benefit these populations include the continuation
of prescribed burns as well as routine trail and firebreak maintenance.
Key Words: Cicindela patruela, tiger beetle, conservation, distribution, habitat
characterization, habitat management
The tiger beetle Cicindela patruela states of Maryland and Massachusetts
Dejean is distributed throughout much (Maryland Department of Natural Re-
ofnortheastern North America, where it sources 2003, Massachusetts Division of
is associated with pine or oak barrens Fisheries and Wildlife 2004).
ecosystems on sandy soils. Typically Three subspecies are recognized with-
C
occurring in small, localized populations, in patruela (Werner 1993, Pearson
this species has become the subject of et al. 2006). The nominate form, green
conservation concern in recent years, with white elytral markings, occurs
C
Extirpations of patruela populations sporadically from Massachusetts west
have been reported in New York to Minnesota and south through the
(McCabe 1995), the District of Colum- Appalachian Mountains to northern
bia, and Maryland (Glaser 1984, Georgia (Kaulbars and Freitag 1993).
Mawdsley 2005), and this species cur- Cicindela patruela huberi Johnson from
rently is listed as "Endangered" by the central Wisconsin differs from the nom-
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
inate form in having brown or black and May. 2006. I visited all four ofthese
dorsal coloration with white markings sites in search ofadult C. p. consentauea.
(Johnson 1989). Cicindela patruela cou- On these trips. I also examined sixteen
seiuanea Dejean. a black fomi with white additional sites in the New Jersey Pine
elytral markings, was reported histori- Barrens which were occupied b}' popula-
cally from the Atlantic coastal plain tions of other tiger beetle species. These
from Long Island south through New additional sites are mostly unpaved sand
Jersey to the Delmarva peninsula (Kaul- roads and trails, although power line
bars and Freitag 1993. Freitag 1999). rights-of-way, abandoned sand pits, and
Recent studies have investigated vari- roadside clearings were also included. I
ous aspects of the biology and distribu- selected the dates of these trips (except
tion ofboth the nominate subspecies and for the July visit) to coincide with the
C. p. huberi (Knisley et al. 1990: Wilhs greatest number ofpast collections of C
2000. 2001). This paper summarizes the p. consentauea. as indicated by museum
known information regarding the biolo- specimen labels.
gy and distribution of C. p. consentanea. Because C p. consentauea is closely
provides a more robust characterization associated with woodlands, I was in-
of the habitat at sites occupied by terested in determining whether certain
populations of this subspecies, and iden- features of forest stand composition and
tifies potential management strategies structure were characteristic of sites
that may help insure the long-term occupied by this subspecies. According-
survival of this tiger beetle. ly. I used standard techniques to assess
Materials and Methods forest stand composition and quantify
stand structure at the four sites where
For this study. I examined the com- adults of C p. consentauea were found.
plete collections of Cicindela patruela in Specific measurements taken at each site
the American Museum of Natural His-
included: diameter at breast height
tor\- (AMNH) and the National Muse- (DBH, measured 137 cm above mean
um of Natural History, Smithsonian ground level) of a random sample of 10
Institution (NMNH).C which included or more Pinus rigida and 10 or more
287 specimens of p. consentauea. Quercus spp. along trails where adults
Ninety-two of the specimens in both
were observed; stand basal area, estimat-
museums were collected during intensive ed as the average ofmeasurements made
searches for this subspecies in the 1970s
using a ""cruiser's crutch" tool at 10
and 1980s by H. Boyd. D. Pearson, J. randomly selected points along occupied
pHSrhooewvpaiprdaerddd,BmoeJy.dwSitt(hainmhailtistotv.o),wnaa,lsnoudngpEru.abcliSiotsiuhlseelsdy. praatnhdso:mlmyaxisemluecmtedheiugnhdtesrsotforayt lseahsrtubs1;0
and the width of paths on which adult
data regarding these latter collections,
beetles were found, measured at 5
which included data on an additional 547
randomly selected points (these paths
specimens which were captured between
1971 and 1982. tended to be fairly uniform in width;
From museum specimen labels, I was thus, only a smaller number ofmeasure-
ments was taken).
able to identify four specific sites in
Burlington and Ocean counties. New Results
Jersey, at which specimens of C. p.
consentauea were collected in the 1970s Historic Distribution
and 1980s. During May and September. The following list of sites represents
2004. May, July, and September, 2005, the known historic distribution of C p.
VOLUME NUMBER
109, 1 19
Fig. 1. Collecting localities for Cicindela patruela consentanea. mapped using ArcView Geographic
Information System software. Open circles indicate historic (pre-1970) collections; closed circles indicate
collections between 1971 and 1982; open stars are the author's study sites; question marks indicate state
records only.
consentanea. Boyd (1978) and Leonard Fries Mill. Middlesex County: Brown-
(1926) have summarized many of the town, 13-Oak Forest. Ocean County:
older records from New Jersey and New Bamber Lake, Brackenville. Brookville,
York based on material from multiple Cassville, Cedar Bridge, East Plains,
museum collections. Localities followed Lacey Township, Lakehurst, Lakewood.
AMNH NMNH
by or represent new Manchester, Whitesville. Whiting (Boyd
records from these museum collections. 1978).
A Geographic Information System (GIS) NEW YORK: Queens County: Alley
map showing these localities is provided Pond (Malkin 1941). Suffolk County:
as Fig. 1. Bay Shore (NMNH), Port Jefferson,
DELAWARE: Sussex County: Mil- Riverhead, Westhampton, Wyandanch
ford (Glaser 1984; Knisley and Schultz (Leonard 1926).
PENNSYLVANIA: No
1997). locality spec-
MARYLAND: No (NMNH).
locality specified ified
(NMNH). There are also unconfirmed reports of
NEW JERSEY: Atlantic County: specimens of C p. consentanea from
Buena, DaCosta, Weymouth. Burlington Rhode Island and Massachusetts (Boyd
County: Atsion, Batona Trail (AMNH), 1978 and in litt.). The museum specimens
Batsto (NMNH), Browns Mills, Car- that I examined from these two states
C
ranza Memorial, Chatsworth, Harris were all from the nominate form, p.
Station, Marlton. Medford, Mt. Misery, patruela. Leonard and Bell (1999) re-
New Gretna, Quaker Bridge, Retreat, viewed the tiger beetle fauna of these
Taunton Lakes, Upton Station, West states in greater detail and also examined
Plains, Whitesbog. Camden County: historic specimens from the relevant
Atco, Pine Hill. Cape May County: regional collections; these authors like-
Seaville, Wildwood. Gloucester County: wise only report the nominate subspecies
20 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
of C. patruela from Massachusetts and counties. Howard Boyd and other tiger
Rhode Island. beetle workers (D. Pearson, J. Sheppard,
J. Stamatov, E. Stiles) spent considerable
Present-Day Distribution time and energy searching for this sub-
Ciciiu/c/a pa/riic/a conscnlanea has species in the 1970s and 1980s, with
apparently been extirpated from much the resulting discovery of a number
of its historic range. As discussed in of localized populations (Boyd 1973,
more detail below, recent (post-1941) 1978). The best current estimate is that
records of this tiger beetle are only from there are approximately 10-20 occupied
the Pine Barrens region of New Jersey. sites within the Pine Barrens region
However, this subspecies appears to be (NatureServe 2005), although, as dis-
widely distributed within this region cussed at the end of this paper, there
and may even be locally abundant at are reasons to suspect that this may be
certain sites. Fig. 1 indicates localities at an underestimate.
which this species has been collected The most recent (post-1970) collecting
since 1971, including the author's four sites for this tiger beetle are widely
study sites. scattered throughout the Pine Barrens
C
The records of C. p. consentanea from region and it seems probable that p.
Delaware, Maryland, and Pennsylvania consentanea is generally distributed
are based in each case on single speci- throughout this area. Some sites have
mens, which in the case of the Maryland evidently supported large populations in
NMNH
and Pennsylvania specimens in recent years, as demonstrated by collect-
are undated but clearly very old. Given ing records provided to the author by
the lack ofany recent records from these Howard Boyd from the 1970s and early
three states (Knisley and Schultz 1997, 1980s, which indicate that up to 57
Boyd 1978, NatureServe 2005), it is specimens of this tiger beetle were
doubtful whether this subspecies still collected at one site on a single day.
occurs in any of them. The recent collecting sites for C p.
If C. p. consentanea was ever found in consentanea are all located within tracts
either Rhode Island or Massachusetts, it ofland in Burlington and Ocean counties
is no longer present. The species C which are owned by the State of New
patruela is considered extirpated from Jersey and managed for conservation
Rhode Island and only a small popula- purposes, including Bass River State
tion of the nominate subspecies C. p. Forest, Brendon T. Byrne (formerly
patruela survives at the Myles Standish Lebanon) State Forest, Greenwood For-
State Forest in Massachusetts (Leonard est State Wildlife Management Area,
and Bell 1999). Stafford Forge State Wildlife Manage-
The last report of C. p. consentanea ment Area, and the Wharton State
from New York is that ofMalkin (1941). Forest.
There is no recent material of this It should be noted that characteristic
subspecies from Long Island in AMNH, Pine Barrens vegetation can still be
no other recent reports from New York found at sites in several of the other
(NatureServe 2005) and thus this sub- New Jersey counties which have historic
C
species should probably be considered records of p. consentanea (Nature-
extirpated from the state. Serve 2005). Because these areas have
C C
Recent (post-1941) records of p. not been surveyed recently for p.
consentanea are all from the core Pine consentanea, it is not possible to state at
Barrens region of central New Jersey, this time whether or not this tiger beetle
principally sites in Burlington and Ocean still occurs in these counties.
VOLUME NUMBER
109, 1 21
Habitat Characterization widely scattered Q. ilicifolia. The Batsto,
I found adults of C. p. consentanea at Greenwood Forest, and Tabernacle sites
four sites in New Jersey during field trips are open woodlands, with mature trees
in 2004, 2005, and 2006. Two sites where (> 8 meters in height), a relatively open
canopy, and a well-defined understory of
I found adults were locations at which
specimens of C. p. consentanea had been short (< 1 meter in height) shrubs of
species in the genera Vaccinium and
collected in the 1970s and 1980s. Three
Gaylussacia (Ericaceae). The Bass River
sites are located in Burlington County,
while the fourth is located in Ocean site is located in a "scrub" forest
composed ofshort (< 4 meters in height)
County. Adults were found during all six
individuals of P. rigida and Q. ilicifolia,
field trips.
with intermingled shrubs of the genera
In addition to the four sites which
Kalmia (Ericaceae), Vaccinium, and Gay-
were occupied by populations of this
lussacia. Canopy cover is nearly 100% in
subspecies, I observed single adult fe-
the scrub forest. Sedges (Carex spp.,
males on two separate occasions on
Cyperaceae), mosses, and lichens are
large, heavily-trafficked sand roads near
found along the trails and roads at all
two of the occupied sites in May, 2005,
four sites.
and May, 2006. As discussed below, I Forest stand measurements such as
interpret the occurrences of these iso- basal area and average diameter at breast
lated individuals in what are evidently height (DBH) of the canopy trees varied
marginal or unsuitable habitats as repre-
widely between sites (Table 1), suggest-
senting dispersal events, rather than ing that these variables may be less
established populations.
important to the beetles than other
To protect this subspecies from possi- factors such as substrate type or the
ble over-collecting, the exact locations of presence of recent fire. However, it
the occupied sites will be described only should be noted that the greatest num-
in general terms. One of these sites is bers ofadult beetles were observed at the
a sand trail within the Bass River State Greenwood Forest and Tabernacle sites,
Forest, another site is a sandy trail near which are very similar in terms of their
Batsto Village in the Wharton State forest stand characteristics.
Forest, the third site is a firebreak and Exposed substrate at all four sites
associated clearing in the Greenwood consists of unconsolidated fine white
Forest State Wildlife Management Area, sand with intermixed fine dark organic
while the fourth site is a sandy trail near matter, giving the substrate an overall
Tabernacle in the Wharton State Forest. grey appearance. Larger organic matter
All four sites are located in pine-oak (dead leaves, needles, twigs, branches,
woodlands. The dominant tree species at cinders) was distributed sparsely over the
the Batsto site are Pinus rigida Miller surface of the trails. At all four sites the
(Pinaceae) and Quercus marilandica (L.) cover of organic matter on the forest
Miinchhausen, with Q. coccinea Miinch- fioor proper was 100%. As noted above,
hausen and Q. falcata Michaux (all single adult females were encountered on
Fagaceae) also present. The stands at two separate occasions on large, heavily-
the Bass River and Greenwood Forest trafficked sand roads. In both of these
sites consist of P. rigida and Q. ilicifolia cases, the substrate consisted of uncon-
Wangenheim, with Q. stellata Miinch- solidated yellow sand with intermixed
hausen also present at Greenwood For- small (< 2 cm diameter) rounded peb-
est. The Tabernacle site is located in an bles. Howard Boyd, who has had more
almost pure stand of P. rigida, with experience with this subspecies than
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
22
Table 1. Physical attributes and forest stand measurements offour sites occupied by populations of
Cicindelapalnwld coiisciUancci. Ail figures are averages ofmultiple measurements.
VOLUME NUMBER
109, 1 23
generosa Dejean, and some individuals not found on the sand trails occupied by
may make a buzzing noise during the adult beetles at any ofthe study sites.
flight. If they land in the open, adults The Greenwood Forest site (which had
typically remain motionless for some the greatest number ofactive adults of C.
time and are very difficult to find until p. consentanea of any site visited during
they move again. Upon landing, adults this study, and where C p. consentanea
may also run short distances to conceal was the most abundant tiger beetle
themselves under vegetation or organic during my site visits) was carefully
debris. searched for larvae and larval burrows.
Boyd (1973, 1978) noted that adults of At this site, larvae and burrows of
C. p. consentanea were most active in the multiple tiger beetle species, possibly
morning and again in mid-afternoon, an including C. p. consentanea, were ob-
observation which is supported by my served in a small area of sandy soil
own field experiences. During mid-day in a clearing covered with small pebbles
and in the evening, adults conceal (< 2 cm diameter), lichens, mosses, and
themselves under organic debris or low sedges. The larvae ofother subspecies of
vegetation. C patruela are known to occur in similar
Predation on small ants was observed microhabitats located away from the
several times in the field; predatory sand trails where adults are found
behaviors are as described for other tiger (Knisley et al. 1990, Wilhs 2000). Further
beetles (Knisley and Schultz 1997). investigations of the larval habitats and
Reproductive behaviors (mating, mate larval biology of this subspecies are
guarding, and female testing ofsubstrate needed.
prior to oviposition) were only observed A specimen in AMNH from Mt.
during the May field trips. Oviposition Misery is labeled "Reared from larvae,"
was not observed, suggesting that it may suggesting that captive rearing of this
occur in areas away from the sandy trails tiger beetle is possible.
C
where the adults are most commonly The length of the life cycle in p.
found, as is the case with other sub- consentanea is not known, but is proba-
C
species of patruela (Knisley et al. bly at least two years, as is the case in
C
1990; Wilhs 2000, 2001). other subspecies of patruela (Knisley
Other species of tiger beetles were and Schultz 1997).
often found at sites with C. p. consenta-
nea. The most frequently encountered Observations on Population Dynamics
species included C. purpurea purpurea Adult activity in C. p. consentanea is
Olivier (2 sites, but abundant at both), C. on a "spring-fall" cycle, as is the case
scutellaris rugifrons Dejean and C. tran- with the other subspecies of C. patruela
quebarica tranquebarica Herbst (both (Knisley and Schultz 1997; Wilhs 2000,
present at 3 sites, but in smaller num- 2001). Adults emerge in late summer, are
bers), and also C. sexguttata Fabricius active for several weeks, and then dig
(common at 2 sites in May only). Species burrows in loose sand or under objects
found in small numbers included C. on the ground where they spend the
formosa generosa Dejean (1 individual winter. In the spring, they re-emerge,
at 1 site) and C. punctulata punctulata mate, and the females oviposit. Based on
Olivier (2 individuals each at 2 sites). museum specimens and other collecting
records (Fig. 2), fall activity in C. p.
Larval Biology consentanea commences during the last
Larval biology was not studied in week in August and peaks in mid-
detail. In general, larval burrows were September, with occasional adults found
24 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
350-1
VOLUME NUMBER
109, 1 25
designing surveys or monitoring proto- a single day at an occupied site. Given
cols. the strong likelihood of dispersal by
The sex ratio in C p. consentanea is adults, it is probable that these small,
evidently close to 1:1; ofthe 287 museum scattered populations are actually part of
specimens examined, 148 were males and larger meta-populations. If this is in fact
139 were females. the case, the effective population size
As with other tiger beetles (Knisley would be larger than the number of
and Schultz 1997), there is some evidence beetles observed at any one site.
to suggest that adults of C. p. consenta- Long-term population trends of C. p.
nea may disperse from occupied sites. consentanea in New Jersey are also
Adults are strong flyers and certainly difficult to assess. This tiger beetle has
have the capability to disperse long always been a challenge for collectors to
distances. The observations noted above find in the field, and thus it is difficult to
of single beetles on heavily trafficked infer past population sizes from either
sand roads in May are perhaps best published accounts or museum specimen
interpreted as examples ofsuch dispersal. records. Leng (1902a) says "it is the least
On the subject of dispersal, it is in- abundant ofthe Pine Barrens Cicindelae,
teresting to note that most of the speci- but under favorable circumstances a doz-
mens in AMNH and NMNH repre- enmaybetaken in a day," an observation
sent unique, single-specimen collecting which is certainly consistent with my own
events, and that of the 23 localities for recent experiences. Howard Boyd (1973)
NMNH, C
this subspecies represented in introduces his discussion of p. con-
14 are represented by single specimens sentanea with the statement "this is a very
only. Similar patterns are evident in data elusive species" and indicates that he had
presented by Boyd (1978). It seems only encountered it twice in the period
possible that some of these collections 1940 to 1970. However, from 1971
may represent dispersing individuals, through the early 1980s, Boyd and other
rather than established populations. collectors found C. p. consentanea in large
It is difficult to estimate current numbers at a few sites, with asmany as 57
population size for C p. consentanea. specimens collected on a single day (Boyd
Obtaining an accurate count of active 1973, 1978, andinlitt.).
adults at a particular site is challenging,
given the beetles' cryptic coloration and Discussion and Management
Recommendations
readiness to take flight at the slightest
disturbance. Under even the most opti- Since C p. consentanea has evidently
mal circumstances, visual surveys of been extirpated from much of its former
adult tiger beetles will underestimate range, every effort should be made to
population size by 50% to 80%, with insure that this subspecies is not driven
lower accuracy for woodland taxa (Knis- to extinction through human activities.
ley and Schultz 1997). My own counts of Fortunately, much of the remaining
adult beetles at sites in the Pine Barrens occupied or potential habitat for this
are undoubtedly underestimates. That subspecies has already been protected by
said, the individual populations of C. p. the State of New Jersey and is being
consentanea which I observed are small. actively managed in a manner that
The greatest number of adults that I should insure the long-term viability of
observed at one site on a single day was the beetle populations.
12 at the Greenwood Forest site in The most important management rec-
September, 2004. More typical observa- ommendation for C. p. consentanea is for
tions were of one or two beetles on the continued protection and wise man-
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
26
agcment of the occupied habitats. Sites and sand trails. Continuation of these
at which this subspecies has been col- management practices should help to
lected within the past thirty years are all maintain existing habitats and create
C
within areas which are owned and new areas of suitable habitat for p.
actively managed by the State of New consentanea.
Jersey for conservation purposes. These Given the highly elusive nature of the
areas include Bass River State Forest, adult beetles, modest collecting activities
Brendon T. Byrne (formerly Lebanon) probably pose no significant threat to C.
State Forest, Greenwood Forest State p. consentanea. However, since this tiger
Wildlife Management Area, Stafford beetle evidently has small population
Forge State Wildlife Management Area, sizes, collectors should refrain from
and the Wharton State Forest. Although taking large series of specimens from
I am not aware of occupied sites on occupied sites. The collection of small
private lands, any such sites that are numbers of voucher specimens, especial-
identified through future surveys should ly from newly discovered sites, should be
be made priority locations for land encouraged as long as these specimens
protection efforts (fee title acquisition will be deposited in permanent museum
and/or protective conservation ease- collections. The timing of collecting
ments) to prevent the destruction of the activities is also important, given that
natural vegetative communities through mating and oviposition apparently occur
residential or commercial development. only in the spring and early summer. In
Such development has been responsible particular, collectors should avoid taking
for extirpating C. patruela populations large series of beetles in the fall and
elsewhere (Mawdsley 2005) and would spring before the adult beetles have had
undoubtedly eliminate populations of C a chance to deposit at least some oftheir
p. consentanea were it to occur on eggs.
occupied sites.
Beyond land protection, the ongoing Further Research
management of pine and oak barrens Key research needs for C. p. consenta-
sites is essential to prevent canopy nea include a more detailed study of
closure and the loss of open barrens larval biology and larval habitats as well
habitat (Boyd 1991, Knisley and Hill as more comprehensive surveys for adult
1992). Fortunately the State of New beetles in areas of potential habitat in
Jersey has a long history ofmanagement New Jersey. Based on my field experi-
activities such as prescribed fire, thinning ences, I suspect that there are other
of forest stands, and regular mainte- occupied sites within the core Pine
nance offirebreaks and sand roads in the Barrens area which have not yet come
Pine Barrens, activities which are pri- to the attention of collectors. There are
marily directed at preventing catastroph- literally hundreds of miles of sandy
ic wildfires (Boyd 1991). On the basis of woodland trails on state, private, and
the habitat characterization which has federal lands in south-central New Jer-
been developed in this study, it is clear sey. Many of these trails have probably
that these forest management activities not been searched recently (if at all) for
C
probably benefit p. consentanea. C. p. consentanea. It is quite possible that
Particularly valuable activities include more in-depth surveys will reveal that
the use oflow-intensity prescribed burns this beetle is present at more sites or in
to reduce understory vegetation and larger numbers than are currently
woody debris, as well as the construction known. As precedent, I would cite the
and periodic maintenance of firebreaks experience ofWiUis (2000, 2001) with C.