Biodiversity Studies • Wetland Delineation & Assessment • Habitat Management • GIS Mapping • Permitting
Vernal Pool Survey Results 1717, 1733, 1753 Storrs Road Mansfield, CT
Submitted to: Robert Moskowitz
Submitted by:
Eric Davison Wildlife Biologist Registered Soil Scientist Certified Professional Wetland Scientist
Date: 12-24-19
Davison Environmental, LLC • 10 Maple Street, Chester, CT 06412 • 860-836-6576 • www.davisonenvironmental.com
CONTENTS
1.0 INTRODUCTION ...... 1
2.0 VERNAL POOLS DEFINED ...... 1
3.0 TERRESTRIAL (NON-BREEDING) HABITAT ...... 2
4.0 SURVEY METHODS ...... 2
5.0 SURVEY RESULTS ...... 3 5.1 Wetland Characteristics ...... 3 5.2 Vernal Pool Survey Results & Wildlife Observed ...... 3
6.0 REFERENCES ...... 5
ATTACHMENTS
• Figures 1-2
• Site Photographs
Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
1.0 INTRODUCTION Davison Environmental, LLC conducted a vernal pool assessment within wetlands on three contiguous parcels located on the south side of Storrs Road in Mansfield (the “site” hereinafter). See attached Figures 1 and 2 which illustrate the location of the site. These parcels total +25 acres, with one large contiguous wetland system covering a large portion of the properties.
Davison Environmental was originally retained to delineate the wetlands and watercourses on the site, which was completed in January of 2019. A survey of the delineated wetland boundary was provided by Bohler Engineering and that data was digitized using a Geographic Information System (GIS) software georeferencing tool and plotted onto Figure 2 in order to illustrate the approximate location and extent of the wetlands that were studied on the site.
2.0 VERNAL POOLS DEFINED Vernal pools are ephemeral waterbodies that provide critical breeding habitat for woodland amphibians, particularly mole salamanders (Ambystoma spp.) and wood frog (Lithobates sylvaticus).
Many vernal pool definitions have been developed by both regulatory agencies as well as conservation organizations. While these definitions vary slightly, they all include the same common critical characteristics. In the Northeastern U.S., a recognized source regarding protection of vernal pools is a document developed by Calhoun and Klemens (2002), entitled: Best development practices: Conserving pool-breeding amphibians in residential and commercial developments in the northeastern United States (the “BDP Manual”, herinafter). The BDP Manual provides the following operational definition of vernal pools:
“Vernal pools are seasonal bodies of water that attain maximum depths in the spring or fall, and lack permanent surface water connections with other wetlands or water bodies. Pools fill with snowmelt or runoff in the spring, although some may be fed primarily by groundwater sources. The duration of surface flooding, known as hydroperiod, caries depending upon the pool and the year; vernal pool hydroperiods range along a continuum from less than 30 days to more than one year. Pools are generally small in size (<2 acres), with the extent of vegetation varying widely. They lack established fish populations, usually as a result of periodic drying, and support communities dominated by animals adapted to living in temporary, fishless pools. In the region, they provide essential breeding habitat for one or more wildlife species including Ambystomid
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Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
salamanders (Ambystoma spp., called “mole salamanders” because they live in burrows), wood frogs (Rana sylvatica), and fairy shrimp (Eubranchipus spp.).”
Most vernal pool indicator species enter pools to breed in the late winter or early spring (March- April), with juvenile dispersal from pools occurring from June – October. The exception to this is the marbled salamander which breeds in pools in late summer and early fall (August- September), with juvenile dispersal occurring from May – July.
3.0 TERRESTRIAL (NON-BREEDING) HABITAT Vernal pool wildlife utilize upland (non-wetland) forested habitat adjacent to vernal pools (Colburn, 2004). The forest provides terrestrial non-breeding habitat for amphibians, where they feed on the forest floor and shelter beneath surficial cover objects (e.g., rocks, logs) and within fossorial small mammal burrows.
Forests not only provide habitat, but the trees adjacent to vernal pools are critical to vernal pool ecology, as they contribute to the food web (via detritus inputs), help maintain cool water temperatures, and affect pool hydrology (Colburn, 2004).
Vernal pool amphibians disperse a significant distance into forests surrounding vernal pools. A number of studies have documented dispersal distances of indicator species (Colburn 2004, Windmiller 1996, Semlitsch 1998). Individuals commonly migrate 400-800 meters or more from uplands to their breeding pool (Colburn 2004).
4.0 SURVEY METHODS Site visits were conducted on April 16th and May 10th, 2019. The purpose of those visits was to search site wetlands for larval and adult amphibians in areas of shallow water. This work was timed appropriate to record the early spring breeding activity of vernal pool wildlife. Aquatic and semi-aquatic species were also catalogued. On both site visits two biologists waded through site wetlands and visually surveyed for egg masses, used dipnets to search for larval and adult amphibians within the water column, and cover searched the wetland-upland interface to look for amphibians under cover objects (rocks, logs and other surficial material). On the May 10th survey, two biologists utilized a seine net and dipnets to capture and inventory species located in the deeper portions of the pond and surrounding marsh habitats. During both surveys, any amphibians heard chorusing were also noted.
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Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
5.0 SURVEY RESULTS
5.1 Wetland Characteristics Two wetlands occur on the site. The primary wetland, which occupies a large portion of the survey area, forms the headwaters to Cedar Swamp Brook. The system is part of the Willimantic River sub regional drainage basin. This wetland includes a pond (totaling ca. 1.5 acres) and bordering marsh with a narrow fringing shrub swamp. The northeastern and southwestern portions of this wetland are forested. These cover types are noted on Figure 2.
Wetland hydrology varies across the wetland in response to the variable topography but consists predominately of permanently ponded wetlands. This hydrology has been enhanced and maintained by beaver, as there is an active beaver dam located at the southwest side of the wetland. The western portions of the wetland consist of open water (i.e., pond), while the shallower fringes along the eastern side are densely vegetated. Areas of dense submergent aquatic and emergent vegetation are present within the open marsh portions of the wetland. The southeastern, northeastern and northwestern portions of the wetland are forested. The hydrology in these forested areas is largely saturated to temporarily flooded. The wetland drains in a southwesterly direction (into Cedar Swamp Brook).
A second small wetland (field demarcated by wetland flag #42-53) straddles the southern site boundary near Professional Park Road. This wetland is a small gently sloped forested wetland with a saturated hydrology. The wetland does not contain areas of prolonged standing (or flowing) water and therefore offers little habitat for wetland-dependent wildlife. It is not a vernal pool.
5.2 Vernal Pool Survey Results & Wildlife Observed Wetland-dependent and wetland-associated wildlife observed during the survey work are listed below in Table 1:
Table 1: species observed Common Name Scientific Name Spring peeper Psuedacris crucifer Green frog Rana clamitans Bullfrog Rana catesbeiana Wood frog Lithobates sylvaticus Pickerel frog Rana palustris Gray treefrog Hyla versicolor Redback salamander Plethodon cinereus Red-spotted newt Notopthalmus viridescens
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Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
Table 1 continued… Garter snake Thamnophis sirtalis Painted turtle Chrysemys picta Fish Bluegill Lepomis macrochirus Pumpkinseed Lepomis gibbosus Chain pickerel Esox niger Golden shiner Notemigonus crysoleucas Minnows Birds Mallard Anas platyrhynchos Canada goose Branta canadensis Red-winged blackbird Agelaius phoeniceus Eastern kingbird Tyrannus tyrannus Tree swallow Tachycineta bicolor Barn swallow Hirundo rustica
No vernal pools were found on the site. The wildlife assemblage present is dominated by limnetic species that inhabit open water. These species require permanent flooding, as opposed to seasonal flooding (i.e., along with seasonal drying) utilized by vernal pool species. The littoral zone, located on the fringes of the pond where the water is shallow and emergent and submergent vegetation occur, is occupied by species that favor marsh habitats such as spring peeper and gray treefrog, along with a small breeding population of red-winged blackbird.
A single vernal pool indicator species, the wood frog, was confirmed breeding in the wetland. Areas where wood frog egg masses were observed are shown on Figure 2. The total number of egg masses observed indicates a small breeding cohort was present during the 2019 season. A total of 5 egg masses were found in the shallow water along the southern shoreline. An additional 11 egg masses were found downstream of the dam spillway in the northwestern area of the wetland.
Wood frog recruitment (i.e., successful maturation to adulthood) rates are expected to be low in this wetland due to the presence of multiple competitor and predatory species. The pressure of competition and predation typical make these permanently flooded wetlands (i.e., ponds, marshes) of low value for vernal pool indicator species. Species that prey on wood frog larvae and egg masses were found to be abundant throughout the wetland, including fish, bullfrog, green frog, painted turtle and red-spotted newt. Of particular note was the presence of large numbers of fish captured during seine sampling on May 10th. Five separate fish species were recorded, along with gravel nests observed along the upstream side of the beaver dam. Where 4 | Page
Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
the ponds transitions to shallower marsh habitat, high densities of bullfrog and green frog were observed, both of which predate wood frog larvae.
It is typical to find wood frog in a variety of wetland types beyond traditional vernal pools, including ponds, marshes and riverine backwater, as this species readily moves across the landscape in an effort to colonize new habitats. 15-20% of juvenile wood frog disperse from their natal pool and breed elsewhere (Colburn 2004). In large early-successional wetlands such as this, it is not unusual to observe wood frog breeding along the forested margins of the wetland where discrete areas of seasonally flooded hydrology can occur. At this site, areas of suitable seasonally flooded hydrology are limited, and areas with ample water to support breeding and metamorphosis are laden with predators and competing species. This is not to say that this wetland is incapable of supporting a small wood frog population, but that long-term establishment of a robust population is unlikely, and the site may function as a population sink.
The predominance of permanent flooding (as opposed to seasonal flooding and drying), and the presence of fish, makes this wetland non-compliant with the physical and hydrologic characteristics of a vernal pool. Seasonal drying is a critical feature of a vernal pool, as it prevents the establishment of fish populations, limits the distribution of large invertebrate predators (e.g., water beetles and dragonflies) and excludes some amphibians that overwinter in water as tadpoles, including green frog and bullfrog (Colburn 2004).
During the non-breeding season, wood frog present on the site can be expected to utilize the upland forest located on the southern side of the wetland as noted on Figure 2. No significant terrestrial habitat was found along the northern limits of the wetland, as existing development has converted these areas to impervious surfaces, graded and compacted earthen fill slopes, and non-forested habitats, all of which are of low terrestrial habitat value for wood frog.
While we did not exhaustively survey for other wildlife suites, other wetland-dependent and wetland associated species observed are noted in Table 1. This includes several birds, along with beaver which remain active in this wetland. During our May 10th survey, an adult beaver was observed, and recent repairs and maintenance to the dam were noted.
6.0 REFERENCES Connecticut Environmental Conditions Online (CTECO) (http://www.cteco.uconn.edu/)
Dowhan, J. and R. J. Craig. 1976. Rare and Endangered Species of Connecticut and Their Habitats. State Geological and Natural History Survey of Connecticut.
Mitsch, W.J. and Gosselink, J.G. 2007. Wetlands, fourth edition. John Wiley and Sons, Inc.
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Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
Calhoun, A.J.K. and M.W. Klemens. 2002. Best development practices: Conserving pool-breeding amphibians in residential and commercial developments in the northeastern United States. MCA Technical Paper No. 5, Metropolitan Conservation Alliance, Wildlife Conservation Society, Bronx, New York.
Colburn, E.A. 2004. Vernal pools, natural history and conservation. The McDonald & Woodward Publishing Company.
Semlitsch, R.D. 1998. Biological delineation of terrestrial buffer zones for pond-breeding amphibians. Conservation Biology 12:1113-1119.
Windmiller, B.S. 1996. The pond, the forest, and the city: Spotted salamander ecology and conservation in a human- dominated landscape. Ph.D dissertation, Tufts, University, Meford, MA.
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Vernal Pool Assessment Storrs Road, Mansfield, Connecticut
______FIGURES 1 and 2
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Copyright:© 2013 National Geographic Society, i-cubed
FIGURE 1 SCALE Site Boundary (approximate) Location Map 0 750 1,500 Feet Storrs Road ¯ Mansfield Davison Environmental, LLC Map Description 10 Maple Street The location and extent of features illustrated are approximate only. Chester, CT 06412 This map is intended for illustrative purposes only. It contains no 860-803-0938 authoritative data. UV195
Forested Wetland
Forested Wetland .! .!
Emergent Marsh Pond Emergent Marsh
Beaver Dam .! Forested Wetland
Forested Wetland
Suitable Terrestrial Forest for Wood Frog
Forested Wetland
k o o r B p m a w S r a d e
C ¤£44 P ro fe s s io n a l P a rk R o a d
FIGURE 2 SCALE Site Boundary (approximate) Aerial Site Map 0 125 250 Feet Storrs Road .! Areas with low numbers of wood frog egg masses ¯ Mansfield Wetland Boundary (approximate) Davison Environmental, LLC Map Description 10 Maple Street The location and extent of features illustrated are approximate only. Chester, CT 06412 This map is intended for illustrative purposes only. It contains no 860-803-0938 authoritative data.
______SITE PHOTOGRAPHS
Photo 1: pond habitat looking northeast (April 16th)
Photo 2: pond habitat looking east (May 10th)
Photo 3: beaver dam (looking south)
Photo 4: open marsh habitat
Photo 5: forested wetland area where wood frog egg masses were located in a discrete pool; note small extent of ponded area with surrounding saturated hydrology
Photo 6: wood frog egg mass cluster
Photo 7: bullfrog tadpole
Photos 8 and 9: golden shiner (left) and chain pickerel (right) were abundant in open water areas