Georgia Keene
Edna Bailey Sussman Foundation Final Report
“Conservation of the Karner blue butterfly at the Albany Pine Bush
Preserve”
Rationale
Habitat loss and degradation have contributed to declines in many threatened
moth and butterfly populations. The federally listed Karner blue butterfly (hereafter Kbb)
occurs at the Albany Pine Bush Preserve (APBP) in Albany, NY as one of six disjunct
relic populations in the region. The Albany Pine Bush Preserve Commission protects and
actively manages habitat for KBB and 43 other New York State species listed as those of
Greatest Conservation Need.
The APBP is a unique inland pine barrens, threatened by urban sprawl,
fragmentation, fire suppression, and invasive species. After dwindling to only a few
hundred hectares of prime habitat in the 1980s, extensive restoration efforts have been
ongoing across the 1500 hectare preserve. Management has focused on maintaining and
restoring open canopy pitch pine-scrub oak barrens, the understory of which contains
both wild blue lupine and the nectar plants that Kbb uses to carry out its life cycle.
Despite extensive restoration efforts, the fragmented nature of the preserve and the
limited dispersal capability of Kbb has hindered colonization of some sites.
It was proposed to carry out a capture, rear and release program to accelerate
colonization of this federally listed species. Habitat suitability was to be determined at
several sites by evaluating the abundance of wild blue lupine, the diversity of nectar
plants, and overall habitat structure, all key determinants of Kbb success. These metrics
are core components of the 2003 U.S. Kbb Recovery Plan.
Frost pockets are low-lying areas on glacial outwash plains where cold air can
become trapped and delay the seasonal life cycle timing of the organisms within them. It
was proposed to deploy temperature data loggers along frost pocket gradients throughout
the preserve. These data, when coupled with rare moth and butterfly monitoring data,
including my own, would allow me to assess potential effects of this unique microclimate
on the abundance and distribution of these insects.
It was proposed to sample vegetation in 1000 m2 plots throughout the preserve
that have been managed for restoration. These data will be compared to a baseline data
set collected prior to initial management efforts in 1991. These surveys were to contribute
to my understanding of how pine barrens management affects plant communities, and the
herbivorous insects that depend on them.
Work completed
On June 3, 2013, during the first brood of Kbb adults, 22 females were collected
at 5 sites and transported to the New Hampshire Fish & Game rearing facility. At the
facility, staff mated the butterflies and reared the resulting larvae. Females averaged
49.76 eggs each. Once the larvae pupated 82% of them were returned to the APBP to be
released for accelerated colonization during the second brood. The remaining pupae were
to be released upon eclosion at suitable sites in New Hampshire.
Once they arrived back at the APBP, the Kbb pupae were placed in sterilized petri
dishes and placed in mesh rearing boxes. The pupae were counted and re-sorted daily,
and a detailed inventory of each rearing box was kept. Newly emerged butterflies were
released daily. In total, 462 butterflies were released. 34 were released at the sites where
females had been collected during the first brood in order to replace them. The remaining
428 butterflies were released at a site in the southwest portion of the preserve with
abundant lupine (Figure 1).
Figure 1: Map showing the southwestern area of the APBP where Kbb were
released for accelerated colonization (red), and the nearby site, inhabited by Kbb,
where distance sampling was carried out (blue lines indicate walked transects).
Throughout the summer vegetation transects were sampled for both species
composition and habitat structure. Lupine abundance and presence of various nectar
plants, including New Jersey tea and butterfly milkweed, were recorded. Additionally,
long-term landscape-level research plots were evaluated on the same metrics. At these
sites, downed woody fuel loads were measured. Data from these objectives will be
analyzed to determine how management affects plant communities in the APBP, as well
as to assess fuel loads and fire risk at these sites.
In addition to carrying out capture-rear-release work with Kbb, I contributed to 19
rounds of distance sampling surveys over two broods of adult butterflies. These surveys
took place at 20 sites around the APBP. Distance poles with “bins” delineating distances
from the transect line were carried during each survey. Average wind speed, maximum
wind speed, and average temperature were recorded before each survey using a Kestrel ®
handheld weather recorder. Surveys were tape recorded. Start and end times for each
transect were spoken into the voice recorder. At each butterfly detection point, the
number of butterflies observed and their distance from the pole were recorded.
During the second brood peak, 28 additional sites were visited 3 times each to
determine whether Kbb were present or absent. It was determined that in addition to the
20 distance sampling sites, Kbb were present at 11 of the presence-absence survey sites,
indicating that any population estimates resulting from distance sampling are
conservative, as Karners either persist at or have colonized these additional sites
throughout the preserve.
250
2007
2008
2009
2010
2011
2012
2013
Count
200
150
100
50
0
29 Apr
19 May
8 Jun
28 Jun
18 Jul
7 Aug
27 Aug
Date
Figure 2: Raw counts for both broods of Kbb from 2007-2013. Data provided
by Albany Pine Bush Preserve Commission.
On March 15, 2013, well before temperatures had warmed enough to trigger
insect development, sixteen temperature data loggers were deployed along frost pocket
gradients at four sites around the APBP. These loggers recorded temperatures every 100
minutes until June 28, 2013. On May 9, 2013, 37 additional data loggers were deployed
at those same sites, which remained in the field until well past the second brood of Kbb.
These loggers were deployed at 10 meter intervals to provide fine-scale temperature data,
and were divided among sites depending on site size. These temperature data were
evaluated using digital elevation models and cokriging in GIS software.
Discussion
Assuming the 428 butterflies released in the accelerated colonization program
have successfully mated and their offspring overwintered, Kbb will be present at that site,
which can be monitored in future seasons using both distance sampling and presenceabsence surveys. Of note is that a well-monitored subpopulation of Kbb exists to the
southeast of the site where Kbb were released (Figure 1). The unit that connects these two
sites was managed with fire in Spring 2013. These 428 butterflies were released in an
adjacent unit in hopes that this recently managed habitat will create a southeasternleading corridor for Kbb dispersal between sites, as well as provide a new site for
colonization.
Raw Kbb counts from the APBP suggest that both 2013 broods were larger than
they have been in the past 7 years (Figure 2). This may indicate a generally increasing
population or a particularly successful year for Kbb. Future monitoring will shed light on
this trend. One site in particular seemed to drive the high numbers: in 2012, the highest
number of butterflies observed in one day across several sites was 79, whereas this year
127 butterflies were observed in one day at this site alone. The federal recovery threshold
for Kbb is 3000 adults occuring in either brood during 4 of 5 consecutive years. This year
the second brood was estimated to contain >5000 individuals, suggesting that the Kbb
population has met the first year’s requirement for the federal recovery threshold. Further
monitoring will indicate whether the population continues to meet the requirements for
the threshold.
Figure 3: Average daily minimum temperatures (in °C) from May 10-June 3, 2013
in and around frost pockets, with predicted temperature gradients generated using
cokriging. This is a Kbb distance sampling site.
Frost pockets were visualized in GIS using cokriging of temperature data
collected with data loggers at 10 meter intervals expressed over a digital elevation model
(Figure 3). These pockets can affect the seasonal timing of insects like Kbb. An
experiment conducted on the larvae of inland barrens buck moth, which co-occurs with
Kbb at the ABPB, suggests that hatch date is significantly delayed within frost pockets
(p=0.036). In addition to delayed hatch, insects in frost pockets may experience slower
accumulation of degree days, which are a measure of the time it takes for an insect to
develop above a specific temperature threshold. Similarly to buck moth, Kbb may
experience a phenological lag in frost pockets as a result of colder temperatures, causing
those in frost pockets to develop less quickly as larvae and thus pupate and emerge as
adults later on in the brood than their non-frost pocket counterparts, depending on which
seasonal cues Kbb use for adult emergence. This would likely only directly affect the first
brood of Kbb, as frosts occur into late spring, when the adults of this brood begin to
emerge.
Degree days accumulated
160
140
120
100
80
60
40
20
0
low
mid
low
mid
high
Blueberry Hill
high
low
mid
low
mid
high
high
Kings Road Barrens
low
mid
high
high
Karner Barrens West
low
mid
low
mid
high
Karner Barrens East
Site & elevation
Figure 4: Degree days accumulated between March 15, 2013 and June 28, 2013 at
four (or three where data loggers failed) elevations at four sites at the APBP.
Indeed, in 2013 degree day accumulations were generally lower in frost pockets
(low and mid-low elevations, generally) than outside of them (mid-high and high
elevations, generally) in 2013 (Figure 4). It is important to note that the “mid-high”
elevation at Kings Road Barrens actually fell within a frosted area, and the “low”
elevation at Blueberry Hill did not, and thus these elevations are only a general
framework in which temperature loggers were deployed.
The disparity in hatch date and development rate that results from colder
temperatures in frost pockets can affect the synchrony between insects and their natural
enemies, affecting both survivorship and reproductive success. Kbb are associated with
non-obligate mutualist ants that tend their larvae. Future studies could incorporate the
seasonal timing of both natural enemies and this mutualist species to evaluate further how
frost pockets may affect this federally-listed species.
A male Karner blue butterfly observed before the first distance sampling survey for
the first brood of adults on May 22, 2013.