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 2012 Accomplishments and Observations
Prepared:
By:
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March 25, 2013
Bryan Windmiller, President, Grassroots Wildlife Conservation
Ian Ives, Sanctuary Director, Massachusetts Audubon Society
John Berkholtz, Senior Keeper, Zoo New England
Reintroduction of the Eastern Spadefoot Toad
Scaphiopus holbrookii
to the Ashumet Holly Wildlife Sanctuary, Falmouth, MA
Summary of 2011 Accomplishments and Observations
I
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, Falmouth, MA in the 1980’s, where males were heard calling from
unsuitable breeding habitat1. All indications are that the species is currently absent from
Ashumet Holly Wildlife Sanctuary (ASH).
In 2011, with permission from the Massachusetts Division of Fisheries and Wildlife (Scientific
Collecting Permit #178.11SCRA), we began a reintroduction effort to re-establish 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 two de novo small breeding pools in an upland
area of ASH in April 2011 with the assistance of USDA wetland creation expert, Tom
Biebighauser. We then translocated a total of 2,170 headstarted spadefoot toads to the vicinity of
the new pools at ASH in June, 2011. All the translocated S. holbrookii were captured as early
stage larvae from vernal pools that were about to dry up completely in the Sandy Neck
Reservation in Barnstable, MA and then headstarted to either metamorphosis (1,871 of the
translocated individuals) or to about one month beyond metamorphosis (327 individuals).
Headstarting was done, according to protocols we had worked out in earlier years, in 10 school
classrooms and three other sites.
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.
2
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.
1
Several males were reported calling in Grassy Pond, a permanent pond with fish, by Jeff Boettner (pers. comm. to
B. Windmiller). More details on prior observations of S. holbrookii are provided in our 2010 Scientific Collecting
Permit Narrative.
2
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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.
Breeding Site Creation and Management at ASH in 2012
The two spadefoot toad breeding sites that we constructed in 2011 retained water with a
maximum depth of 12 – 15 inches on a permanent basis and thus did not yet exhibit the
ephemeral hydroperiod preferred by eastern spadefoot toads (Greenberg and Tanner, 2005). To
adjust these pools (Pools #1 and 2) to a more ephemeral hydroperiod we attempted two
management options in 2012: we punctured the liner of Pool #1 in two places about 6 inches
below the lip of the liner, and we drained both pools as completely as possible using a portable
sump pump in August, 2012.
Additionally, we created two new potential spadefoot toad breeding sites in a more wooded area
in ASH in May, 2012. These two pools were, like Pools #1 and 2, created de novo in upland
habitat and thus were made with a durable plastic liner. These pools were created to be
shallower (maximum depth of 8” and 9”) and will hopefully dry naturally during the summer.
Breeding pools #1 and 2 have been colonized by a wide variety of wetland forb and graminoid
plant species and are used as breeding habitat by: spotted salamanders (Ambystoma maculatum)
wood frogs, (Lithobates sylvaticus), green frogs (L. clamitans), and gray treefrogs (Hyla
versicolor). Additionally, we have observed several small species of dytiscid beetle, water
striders, backswimmers, and odonate larvae in the pools.
II
Headstarting and Translocation of 2012 Eastern Spadefoot Toad Cohort
Ian Ives observed breeding activity by eastern spadefoot toads at Sandy Neck on the night of
May 15-16, 2012. On the nights of May 17 and 20, Ian collected spadefoot toad eggs from four
small ephemeral pools near the Sandy Neck Gatehouse that were dry within 10 days of egg
deposition. The eggs were allowed to hatch in an aquarium and a total of 2,494 early stage
eastern spadefoot toads tadpoles into our headstarting program prior to release at ASH. Of these:
1,781 were released as tadpoles or metamorphs, 224 were released as post-metamorphic toadlets,
10 were kept by Ian Ives over the winter to study their growth rates, and 479 (19%) died in
captivity (see Table 1). Nearly all the deaths (96%) occurred at the Bristol Agricultural High
School when the aeration apparatus failed. (Please note that these numbers update those on the
annual report for Scientific Collecting Permit 123.12SCRA.)
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Table 1: Disposition of Headstarted Eastern Spadefoot Toads
Headstarting Locations Long Pasture Wildlife Sanctuary Bristol County Agricultural High School Drumlin Farm Wildlife Sanctuary and 3 Off-­‐
Cape Schools Overall for Project III
Total Early # Released as # Released Stage Tadpoles Tadpoles or as Entered Into Metamorphs
Toadlets # Dead Headstarting (%) (%) (%) 1,840 1590 (86.4%) 224 (12.2%) 509 50 (9.8%) 0 145 2,494 16 (0.9%) 459 (90.2%) 4 (2.8%) 479 1781 (71.4%) 224 (9.0%) (19.2%) 141 (97.2%) 0 # Kept Overwinter (%) 10 (0.5%) 0 0 10 (0.4%) Observations on Eastern Spadefoot Toad Breeding at Sandy Neck
The spring months of 2012 were unusually dry on Cape Cod, and vernal pool water levels at Sandy Neck reflected this. In Barnstable, only 6.34” of precipitation fell from January through April in 2012, compared to the 14.05” that falls on average during that time period. As a result, breeding pools on Sandy Neck were dry from January through April and spadefoot toads were not actively chorusing and breeding during that period. The first recorded chorus’s were witnessed on May 10, as opposed to April 13th in 2011, March 29th in 2010, and April 6th in 2009. The first egg masses deposited in Sandy Neck pools were on May 17. The latest egg deposition date documented in any of the prior 3 years was April 22. Documented breeding pools for 2012 are indicated in Figure 1. For the fourth year running, there was no witnessed successful metamorphosis from any of the documented breeding pools at Sandy Neck. Below is a summary of the breeding season at the site. May 10 2012: 2.51” of rain reported in the last 24hrs. Temperature 51F. NE Winds 8mph-­‐ gusting 15mph. Location of Survey: Sandy Neck Rd and surrounding vernal pools •
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3:20pm: Checked all documented breeding pools around gatehouse area. All but 2 were dry. No eggs or adult Spadefoots seen. Presumed chorusing activity on night of •
May 9, as reports of chorusing spadefoots were made at Provincelands and Westport MA. 6:30pm: up to 4” of water at horse trail pools on east end of Sandy neck, but no eggs seen. May 17, 2012: 1.96” of rain reported in last 24 hrs. Temperature 66, clowdy. Location of Survey: Sandy Neck Rd and surrounding vernal pools •
•
2:30pm: looked for egg masses in all documented breeding pools around gatehouse area. Documented approximately 150,000 spadefoot toad eggs at 5 pools in this area. 3:30pm: collected approximately 2000 eggs from Sandy Neck barrier beach from 4 pools at gatehouse area. Some of the tadpoles that hatched from these eggs were later released. Notes: •
•
•
Presumably, eggs seen were deposited on night of 5/15 & 5/16. Rain started after 10pm on 5/15, and continued heavily till 8am, then drizzle till noon on 5/17. Presumably, the 5/9 storm triggered chorusing, and following storm initiated amplexus. May 20, 2012: No measurable rain in last 3 days. 69F, sunny. Location of Survey: Sandy Neck Rd and surrounding pools •
10am: Collected an additional 1150 tadpoles from pool near gatehouse August 12, 2012: 3” of rain in last 2 weeks. Only 7.3” of rain since May 20, and a maximum of only .85” of rain on any given storm (not nearly enough to create puddling in a pool for more than 24 hrs). 80F, sunny. Location of Survey: Sandy Neck Rd and surrounding vernal pools 2pm: Surveyed all gatehouse pools. No water in any of the documented breeding pools. Notes: Given data through May 20th, and insufficient rain between May 20 and August 12 to trigger breeding bouts, and fill any pools for more than a day, it can be assumed that no tadpoles survived to metamorphoses this season on Sandy Neck. •
IV
Plans for 2013
In late 2011, Mass Audubon staff installed drift fence pitfall trap arrays around ASH Pools #1
and 2. We plan to close the fences and open the traps on these arrays and trap around these two
pools for two months in 2013. This trapping will allow us to survey for subadult spadefoot toads
(those from the 2011 and 2012 cohorts) that might be moving around the pool perimeters.
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Of more likely usefulness, we will be able to use the pitfall trap arrays to determine the
survivorship of direct-released early stage tadpoles in these two pools. To do so, we will direct
release approximately 200 newly hatched Sandy Neck tadpoles into each of the ASH pools with
drift fences and monitor the traps for at least two months post-release. We will also, if possible,
see if pool hydroperiod influences the survivorship of these direct released cohorts by draining
one of the pools prior to the release and leaving the other pool unmanipulated. (We are unable to
replicate these conditions so this will be an anecdotal study.)
We will also install a Wildlife Acoustics “Songmeter” digital recording device near the 2012
ASH pools to monitor the area for spadefoot toad vocalizations. Based on the slow growth of
spadefoot toads kept since the 2011 cohort, however, we think that it may be at least two more
years before any of the 2011 cohort are of breeding age.
In 2013, we hope to repeat the translocation of up to 3,000 headstarted eastern spadefoot toad
metamorphs or toadlets from Sandy Neck to ASH. With the exception of the 400 tadpoles used
in the direct release study, the tadpoles will be headstarted to at least Gosner stage 40 at the Long
Pasture and Drumlin Farm Wildlife Sanctuaries and at a number of schools in eastern
Massachusetts.
In 2013, we hope to conduct a pilot radiotelemetry project at ASH by implanting transmitters in
eight adult spadefoot toads collected at Sandy Neck. We hope that this will allow us not only to
develop our telemetry protocols for the eventual adult spadefoot toads that we encounter at ASH
but we will study the habitat use of the Sandy Neck adults to obtain information about likely
upland habitat preferences of spadefoot toads at ASH. We will request permission to conduct
this study from the Massachusetts Natural Heritage and Endangered Species Program shortly.
Finally, we hope to construct four or five new breeding pools at the Mass Audubon Long Pasture
Wildlife Sanctuary in Barnstable, directly across the Great Marsh from Sandy Neck. If permitted
to do so by the Massachusetts Natural Heritage and Endangered Species Program, we might
begin releasing translocated spadefoot toads at Long Pasture in 2014.
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Error! Objects cannot be created from editing field codes.Figure 1. Confirmed breeding
pools, potential breeding pools and pools confirmed to have had breeding activity in 2012.
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