Preserving Living Treasures in Our Backyards Prepared For:
Jacob Kubel, Conservation Scientist
Massachusetts Natural Heritage and
Endangered Species Program
Reintroduction of the Eastern Spadefoot Toad
Scaphiopus holbrookii
to the Ashumet Holly Wildlife Sanctuary, Falmouth, MA
Summary of 2013 Accomplishments and Observations
Prepared:
April 4, 2014, 2014
By:
Bryan Windmiller,
Ian Ives,
Grassroots Wildlife Conservation
Massachusetts Audubon Society
PO Box 332, Concord MA 01742 v 617-­‐538-­‐4914 v
www.grassrootswildlife.com [email protected] Reintroduction of the Eastern Spadefoot Toad
Scaphiopus holbrookii
to the Ashumet Holly Wildlife Sanctuary, Falmouth, MA
Summary of 2013 Accomplishments and Observations
1.
Overview and Objectives
A small population of eastern spadefoot toads (Scaphiopus holbrookii, Massachusetts
state “threatened” species) was reportedly present in the Massachusetts Audubon
Society’s Ashumet Holly Wildlife Sanctuary (ASH), Falmouth, MA in the 1980’s, where
males were heard calling from unsuitable breeding habitat. All indications were that
local population of eastern spadefoot toads at ASH had been functionally extirpated by
early 2000’s. This extirpation mirrors the widespread loss of eastern spadefoot toad
populations from many areas within their former range in Massachusetts and southern
New England in general.
In 2011, with permission from the Massachusetts Division of Fisheries and Wildlife
(Scientific Collecting Permit #178.11SCRA), we began a reintroduction effort to reestablish an eastern spadefoot toad population at ASH. Our surveys of ASH had
suggested to us that past and future populations of eastern spadefoot toads on the
sanctuary were primarily limited by the lack of suitable breeding habitat. We therefore
excavated four de novo small breeding pools in upland area of ASH in 2011 and 2012
with the assistance of USDA wetland creation expert, Tom Biebighauser.
In 2011, we began translocating eastern spadefoot toads to ASH from a large breeding
population at the Sandy Neck Reservation in Barnstable, MA. In the past three field
seasons, we have translocated a total of 7,174 eastern spadefoot toads to ASH from
Sandy Neck. Of those, 90.2% were first headstarted in captivity to either metamorphosis
(5,177 individuals) or for some period beyond metamorphosis and released as toadlets
(703 individuals). Headstarting was done, according to protocols we had worked out in
earlier years, in school classrooms and nature centers. The remaining 700 eastern
spadefoot toads were translocated as early stage tadpoles with minimal headstarting (see
below).
Our overall objectives for this reintroduction project are to:
1) Establish a self-sufficient meta-population of eastern spadefoot toads at the Ashumet
Holly Wildlife Sanctuary.
Research the captive husbandry, post-release growth and survival, and habitat use by
translocated eastern spadefoot toads to better plan and inform other similar translocation
efforts meant to establish or re-establish populations of this species in suitable habitat
within their former range in Massachusetts.
2)
Involve K-12 students and adult volunteers in this effort to foster their awareness and
sense of stewardship for eastern spadefoot toads and other rare amphibian species.
3)
PO Box 332, Concord MA 01742 v 617-­‐538-­‐4914 v
www.grassrootswildlife.com [email protected] 2 The following report documents our activities and observations in conducting this
reintroduction project in the 2013 field season.
II.
Breeding Site Monitoring at ASH in 2013
The two spadefoot toad breeding sites that we constructed in 2011 (Pools #1 and 2)
retained water with a maximum depth of 12 – 15 inches on a permanent basis in 2013.
Although they have been colonized and used as breeding habitat by spring peepers
(Pseudacris crucifer), gray treefrogs (Hyla versicolor), wood frogs (Lithobates
sylvaticus), green frogs (Lithobates clamitans), and spotted salamanders (Ambystoma
maculatum), their current permanent hydroperiods likely renders them unsuitable as
spadefoot toad breeding sites. A single perforation made in the liner of Pool #2 in 2012
did succeed in lowering its water level somewhat.
The two shallower breeding pools created in 2012 (Pools #3 and 4) were colonized by
spotted salamanders less than one year after their creation in the early spring of 2013. In
total, Ian Ives counted about 50 spotted salamander egg masses in the two pools and 15
adult spotted salamanders were captured in minnow traps in 2012 Pool #3 during a field
trip activity conducted with students of the Sturgis West High School. Both Pools #3 and
#4 dried completely in the late summer of 2013.
III.
Breeding Pool Creation at Long Pasture Wildlife Sanctuary
Ian Ives, with the assistance of Tom Biebighauser and Bryan Windmiller, designed and
constructed five de novo vernal pools on the margins of a field in the Long Pasture
Wildlife Sanctuary in Barnstable, MA, just across Barnstable Harbor from the Sandy
Neck Reservation. Unlike the four upland pools created at ASH, the Long Pasture pools
were excavated either in the margins of a degraded forested wetland or within the
regulatory buffer zone of that wetland. The LP pools were all created without a plastic
liner and were designed to fill seasonally from groundwater and surface flow.
IV.
Capture of Adult Eastern Spadefoot Toad at Ashumet
On June 11, 2013, a single male eastern spadefoot toad was captured entering 2011
Ashumet Vernal Pool #2. This individual, which measured 47mm SVL and weighed
14.1g, was likely a young adult. Its length was near the cut-off criterion used by Kevin
Ryan (pers. comm.) in differentiating eastern spadefoot toads as juveniles or adults in a
study completed in Canterbury, CT. Although it is impossible for us to tell definitely
whether the captured male was one of the tranlocated individuals or a spadefoot toad that
reached the site independently of us, we believe that the latter is much more likely since
it was the only adult observed at Ashumet in 2013 and we think it unlikely that any of the
2011 cohort of translocated spadefoot toads could have grown to that size in two years.
PO Box 332, Concord MA 01742 v 617-­‐538-­‐4914 v
www.grassrootswildlife.com [email protected] 3 V.
Headstarting and Translocation of 2013 Eastern Spadefoot Toad Cohort
In the spring of 2013, Ian Ives first observed breeding activity by eastern spadefoot toads
at Sandy Neck on the night of April 12, 2012. On that night, he collected spadefoot toad
egg masses for the reintroduction project from a small vernal pool located just north of
the air pump station near the Sandy Neck gatehouse. Of the tadpoles that hatched, 700
were released as fairly early-stage tadpoles (ca. Gosner stage 25) on May 2 into 2011
ASH Pools #1 and 2. These two pools were enclosed by a drift fence – pitfall trap array,
allowing us to quantify the number of the direct released tadpoles that later emerged as
metamorphs, an indication of their rate of survival to metamorphosis. In total, Ian Ives
and assistants Gynn Silva, Elise Ludec, and Sean Kortis, captured 57 individuals
metamorphs leaving the two ponds in June, indicating a survival to metamorphosis of less
than 10% among the direct-released tadpoles.
A further 2,832 tadpoles were then assigned to our headstarting program. Ultimately, of
those tadpoles, 533 (18.8%) died during headstarting, 2,147 (75.8%) were released at
ASH as metamorphs, and 152 (5.4%) were released at ASH as toadlets. Headstarting
was conducted at nine schools (Barnstable United Elementary School, Falmouth High
School, Sturgis West High School in Hyannis, Thoreau Elementary School in Concord,
Ephraim Curtis Middle School in Sudbury, and the Cabot and Franklin Elementary
Schools in Newton) as well as at five nature or conservation centers (Long Pasture, North
River, and Drumlin Farm Wildlife Sanctuaries of Mass Audubon, Sandy Neck
Reservation gatehouse, and the offices of Grassroots Wildlife Conservation). Ten of the
14 headstarting facilities had less than 10% mortality among the headstarted tadpoles and
toadlets that they raised.
VI.
Observations on Eastern Spadefoot Toad Breeding at Sandy Neck
In 2013, Ian first observed spadefoot toad egg masses in a number of small vernal pools
near the entrance to Sandy Neck on April 12; these were likely deposited on the night of
April 10. The egg masses had hatched by April 17 and early stage tadpoles were
apparent. A second breeding event occurred just before April 24, when Ian again found
many egg masses in vernal pools near the gatehouse. Late stage tadpoles were observed
on May 22 and then, on May 27, Ian found thousands of eastern spadefoot toad
metamorphs along the shorelines of two of the gatehouse area vernal pools. This was the
first observation of successful metamorphosis by eastern spadefoot toads at Sandy Neck
since we began our fieldwork there in 2009. Additionally, Ian observed newly laid
spadefoot toad egg masses on May 27, also indicating that the 2013 breeding season at
Sandy Neck was exceptionally long in duration, extending from at least April 10 to May
27.
PO Box 332, Concord MA 01742 v 617-­‐538-­‐4914 v
www.grassrootswildlife.com [email protected] 4 Plans for 2014
In 2014, we plan to conduct the 4th year of headstarting and translocation of spadefoot
toads to Ashumet Holly Wildlidfe Sanctuary. Based on the relatively poor survival or the
direct-released tadpoles in 2013, we will translocate only metamorphs and young toadlets
in 2014. Our conclusion that translocating metamorphs is likely to result in much higher
eventual survival to adulthood than translocating early stage tadpoles is supported by a
recent study on the results of reintroductions of boreal toads (Anaxyrus boreas) in
Colorado (E. Muths et al. 2014. Animal reintroductions: An innovative assessment of
survival. Biological Conservation 172 (2014) 200–208).
Additionally, we plan to assess the suitability of soils at the Long Pasture Wildlife
Sanctuary, where five new breeding pools were excavated in 2013, for upland spadefoot
toad habitat. To do so, we will construct very small enclosures (< 1m2) into which we
will release headstarted spadefoot toadlets so that we can observe if the toadlets can
burrow successfully into the generally loamy soils at Long Pasture.
This spring and summer, we will be conducting a more extensive analysis of spadefoot
toad breeding habitat at Sandy Neck than we have been able to do in the past. Rachel
Jania, a veterinary student at Tufts University, and Sean Kortis, a spring intern with Mass
Audubon – Long Pasture, will lead an effort to survey several dozen vernal pools at
Sandy Neck and compare physical, chemical, and biotic characteristics of the pools in
which spadefoot toads breed to those in which no toads breed in 2014.
At Ashumet Holly Wildlife Sanctuary, Ian Ives, Sean Kortis, and volunteers have
installed a drift fence enclosure around one of the 2012 created vernal pools as well as
around several thousand square feet of upland habitat. We intend to release
approximately 100 individually-marked headstarted toadlets into the enclosure and trap
for them along the inner rim of the enclosure periodically so that we can estimate their
rates of growth and survival.
If possible, we plan on implanting radio-transmitters into up to 8 adult spadefoot toads
from Sandy Neck this spring, translocating them to Ashumet, and monitoring their choice
of upland habitat areas. We hope that this study will allow us to determine the most
favorable upland habitat at Ashumet for spadefoot toads.
PO Box 332, Concord MA 01742 v 617-­‐538-­‐4914 v
www.grassrootswildlife.com [email protected] 5