Distribution Maps for Amphibians and Reptiles at the edge of their range in New York State Lauren

47 Pages·2010·5.45 MB·English

Distribution Maps for Amphibians and Reptiles at the edge of their range
in New York State

Lauren Lyons-Swift, Tim Howard
New York Natural Heritage Program
September 7, 2010

Abstract:
In this report we identify the herpetofauna (amphibians and reptiles) at the edge of their range in NYS. Of
the 74 herpetofauna known to occur in New York, 28 are at the edge of their range in the state with an
additional 7 having a limited but variable distribution. Continental range maps, where available, confirm
this finding. Of the 35 edge-of-range species identified, two had a northern distribution pattern (pages 7-
9), nine were southern (pages 10-19), 12 were southeastern (20-32), five were western (pages 33-38), and
seven were considered variable (pages 39-46). The NYS Herpetological Database (approximately 90,000
records) provides observation records and allows us to present the statewide distributions in a way that
provides perspective on movements of range edges that may have already occurred. Using the NYS
Herpetological Database, we mapped all 35 species with restricted distributions by location and by date of
observation. Dates of observations ranged from 1805 to the present. While some species have some
indication of changes in their distribution, further analysis would be required to quantify these changes.

Introduction:
The State of New York is a crossroads of North Temperate Zone biological diversity. Indeed, seven
different ecoregions cross into New York (Bailey 1997), the south-north transition from oak-dominated
forests to maple-dominated forests largely occurs in New York (Cogbill et al. 2002), and many animals
and plants reach their northern or southern range limits within the state. Particularly in this time of
uncertainty in plant and animal responses to changes in climate, understanding the potential behavior of
edge-of-range species is critical for making projections about how ecosystems are likely to respond to
climate change. Yet a complete list of edge-of-range species for New York does not exist. The purpose of
this project was to begin to rectify this problem by identifying the herpetofauna (amphibians and reptiles)
at the edge of their range in New York State. Recognizing the potential of the database and the fact that
we are in the midst of ongoing climate change, we also explored the possibility of detecting movement in
range edges by mapping the earliest date each edge-of-range species was observed within the boundaries
of USGS quadrangles.

Methods/materials:
1. We began by screening for edge-of-range herpetofauna using the NYS DEC public website
(http://www.dec.ny.gov/animals/7140.html). This site contains distribution maps for 74
amphibians and reptiles found in New York (see example below). These distribution maps show
all USGS 7.5 minute topographic quadrangles in which each species of amphibian and reptile are
known to occur, as based on the Amphibian and Reptile Atlas Project from 1990-1999 (Herp
Atlas Project). For a few species, additional reports collected during the post Atlas period are
included if they represent new locations not previously identified. Some reported observations
may be removed from the database during the final quality review prior to publication of the
results (Ozard 2010). The data collected over the nine year span of the Herp Atlas Project were
more than adequate, for the purposes of this initial screening, to determine the likely edge-of-
range species from the pool of all amphibians and reptiles known to occur in the state.
2. To better refine statewide distributions and better understand the temporal aspect of
herpetological observations throughout the state, we worked NYS DEC staff on the combined
herpetofauna database (NYSDEC 2009; Ozard 2010). This database is maintained by the non-
game unit and includes all amphibian and reptile observations recorded from 1805 to the present.
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Total observations for this database come to over 90,000 records. We ran a series of queries on
the data to eliminate records that lacked dates and/or clear location data. The resulting dataset
contained approximately 70,000 records. Although many records have a higher spatial resolution,
most records are recorded at the level of a USGS quad, an appropriate scale for this project.
3. In order to simplify presentation and explore the possibility that range shifts may already be
occurring, we selected the earliest date each species was observed within a given USGS
quadrangle. The resulting dataset contains just under 20,000 records.
4. We projected the tabular query results into a GIS and created distribution maps for each species.
Species maps were then grouped based on which geographic part of New York State represented
the edge their range.
5. To better understand the relationship between statewide distributions and entire species ranges,
we also examined full range maps for each targeted species.
6. We grouped species by their patterns of distribution within the state and continental range and
present distribution maps, range maps, and species and habitat information organized by this
grouping to best understand the spatial significance of distribution shifts for New York’s
herpetofauna.

Results

Edge-of-range species

Of the 74 amphibian and reptile species known to occur in New York State, we found 35 species with
restricted statewide distributions (Table 1). An additional five marine turtle species also showed a
restricted distribution but were not included in this report. Most of these species with restricted
distributions are clearly at the edge of their range (e.g. Marbled Salamander, Figure 1a). Yet others have a
restricted distribution with patches of populations scattered throughout the state (e.g. Blanding’s Turtle,
Figure 1b). Based on information from the distribution maps, range maps, and known habitat
requirements, we have included these ‘variable’ species in this report because of the potential for them to
shift distribution with our changing climate. Table 1 lists all 35 species alphabetically by common name;
Table 2 groups the species by geographical distribution.

Figure 1. NYS Herp Atlas distribution map for Marbled Salamander (left) and Blanding’s Turtle (right)
exemplifying a typical species at its northern range in Southeastern New York and a species with variable
but limited distribution that may show distribution shifts concomitant with climate change (Source:
http://www.dec.ny.gov/animals/7140.html).

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Of the 35 species identified with restricted distributions, two had a northern distribution pattern, nine
were southern, 12 were southeastern, five were western, and seven were considered variable (limited
distribution but no distinct geographic area). Following Tables 1 and 2, we dedicate a page for each
species and provide a distribution map, a range map, species description, and a description of habitat
preferences to produce “Species Data Pages.” Range maps for each species were taken from a variety of
sources including NatureServe Explorer website (NatureServe 2010) and the IUCN Redlist website
(IUCN 2010). Species pages are grouped geographically below.

Discussion

Our finding that nearly 50% of New York’s herpetofauna show a limited distribution in the state
heightens the significance of how this taxonomic group may respond to our changing climate. Predicting
which of these species are most likely to respond quickly to climate change would require additional
research into habitat preferences, mobility, barriers, and population dispersal life-history traits, just to
name a few. Many of these species are quite mobile, with an ability to travel along stream courses and
connected wetland systems. Yet others may be restricted to very specific habitats with no other real
options within reach of migrating individuals. Understanding these types of habitat needs, habitat
connectivity, and dispersal ability will allow us to better understand the potential for these species
identified here to expand into new parts of the state.

One of New York’s species, the Mink Frog, is clearly a northern species with its population cores in the
Tug Hill and the Adirondacks. This is a species for which we would expect to see a range contraction in
the coming years. We could detect no indication of range contraction already occurring using all the Mink
Frog observation records from the Herp database, but this certainly is a species to watch at its distribution
peripheries.

As stated earlier, every single record of the NYS Herpetological Database has not been fully verified;
some of the spatially ‘errant’ records may be misidentifications. This does not undermine the tremendous
value of this dataset, it simply reinforces that any analysis using these data should focus on core
population areas and not necessarily single outliers. One avenue where additional spatial analysis of these
records would be sure to be fruitful would be in detecting range extensions that are already occurring.
Some of the species that seem to show the most promise for significant range expansions at some sites
include the Northern Black Racer, Eastern Hognose Snake, Eastern Worm Snake, Northern Cricket Frog,
and Spotted Turtle. Spotted Turtle, for example, has a clear core of early records at the north end of its
range in Albany and Rensselear counties with newer records expanding up the Hudson River valley.
Clearly, any analysis attempting to examine such range expansions needs to take into account survey
effort and the large increase in records during the Herp Atlas decade (1990-1999). Still, further analysis is
warranted to see if these difficulties can be overcome.

Other species to watch may be those on the edge of their range in New York that have relatively general
habitat requirements. These species include Western Chorus Frog, Marbled Salamander, Shorthead Garter
Snake, and Wehrle’s Salamander. Introduced species such as the Italian Wall Lizard may also be species
that show early and rapid distributional responses to climate change.

The information in this report provides the jumping off point for exploring which amphibians and reptiles
are likely to move into portions of the state where they currently do not reside. The behaviors and habitat
of any species migrating into or through new habitats are likely to alter food-web and ecosystem
dynamics. Even ecosystem function has been shown to be severely altered with species range shifts,
mostly for invasives (e.g. Brooks et al. 2004, Mack et al. 2000), but the loss or gain of native species may
have similar effects (e.g. Naeem et al. 1999). Thus, understanding which species are most likely to re-
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arrange their distributions in New York will help us take that next step in understanding how changes in
species’ distributions throughout the state may influence ecosystem resiliency and ecosystem function.

Most important, perhaps, is that amphibians and reptiles overall represent a very small component of New
York’s biodiversity. Other vertebrates, invertebrates, and especially plants will be shifting their ranges in
response to climate. We do not yet understand the potential and magnitude of these coming changes. An
obvious first step is to conduct similar edge-of-range analyses for other groups of species. Excellent
spatial data exist for plants, a particularly large group that would require a different, automated approach
to detecting edges-of-range. We hope to move on to this group as time and funding permits.

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Table 1. Herpetofauna with limited distributions New York State, sorted by common name. The final
column, ‘edge of range’ categorizes how each species’ distribution is restricted in the state. Those labeled
as South, for example, indicate species at their northern edge of their range in New York and currently
restricted to the southern portions of the state.
Common name Scientific name Edge of range
Blanding's Turtle Emydoidea blandingii Variable
Bog Turtle Glyptemys muhlenbergii Variable
Common Map Turtle Graptemys geographica Variable
Common Musk Turtle Sternotherus odoratus Variable
Eastern Box Turtle Terrapene c. carolina South
Eastern Hellbender Salamander Cryptobranchus a. alleganiensis South
Eastern Hognose Snake Heterodon platirhinos Southeast
Eastern Massasauga Sistrurus c. catenatus West
Eastern Mud turtle Kinosternon subrubrum Southeast
Eastern Redbelly Turtle Pseudemys rubriventris South
Eastern Spadefoot Scaphiopus holbrookii Southeast
Eastern Spiny Softshell Apalone spinifera Variable
Eastern Tiger Salamander Ambystoma t. tigrinum Southeast
Eastern Worm Snake Carphophis a. amoenus Southeast
Five-lined Skink Plestiodon fasciatus Southeast
Fowler's Toad Bufo fowleri Variable
Italian Wall Lizard Podarcis sicula Southeast
Longtail Salamander Eurycea l. longicauda South
Marbled Salamander Ambystoma opacum Southeast
Mink Frog Rana septentrionalis North
Northern Black Racer Coluber c. constrictor South
Northern Coal Skink Plestiodon a. anthracinus West
Northern Copperhead Agkistrodon contortrix mokasen Southeast
Northern Cricket Frog Acris crepitans Southeast
Northern Fence Lizard Sceloporus undulatus hyacinthinus Southeast
Northern Red Salamander Pseudotriton r. ruber South
Queen Snake Regina septemvittata West
Red-eared Slider Trachemys scripta elegans South
Shorthead Garter Snake Thamnophis brachystoma West
Southern Leopard Frog Rana sphenocephala South
Spotted Turtle Clemmys guttata Variable
Timber Rattlesnake Crotalus horridus South
Wehlre's Salamander Plethodon wehrlei West
Western Chorus Frog Pseudacris triseriata North
Yellowbelly Slider Trachemys s. scripta Southeast
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Table 2. Herpetofauna with limited distributions in New York State organized by geographic distribution.
Species grouped under ‘North’ have a northern distribution in New York and the southern edge of these
species range passes through New York State.

Common name Scientific name
North Mink Frog Rana septentrionalis
Western Chorus Frog Pseudacris triseriata
South Eastern Box Turtle Terrapene c. carolina
Eastern Hellbender Salamander Cryptobranchus a. alleganiensis
Eastern Redbelly Turtle Pseudemys rubriventris
Longtail Salamander Eurycea l. longicauda
Northern Black Racer Coluber c. constrictor
Northern Red Salamander Pseudotriton ruber ruber
Red-eared Slider Trachemys scripta elegans
Southern Leopard Frog Rana sphenocephala
Timber Rattlesnake Crotalus horridus
Southeast Eastern Hognose Snake Heterodon platirhinos
Eastern Mud turtle Kinosternon subrubrum
Eastern Spadefoot Scaphiopus holbrookii
Eastern Tiger Salamander Ambystoma t. tigrinum
Eastern Worm Snake Carphophis a. amoenus
Five-lined Skink Plestiodon fasciatus
Italian Wall Lizard Podarcis sicula
Marbled Salamander Ambystoma opacum
Northern Copperhead Agkistrodon contortrix mokasen
Northern Cricket Frog Acris crepitans
Northern Fence Lizard Sceloporus undulatus hyacinthinus
Yellowbelly Slider Trachemys s. scripta
West Eastern Massasauga Sistrurus c. catenatus
Northern Coal Skink Plestiodon a. anthracinus
Queen Snake Regina septemvittata
Shorthead Garter Snake Thamnophis brachystoma
Wehlre's Salamander Plethodon wehrlei
Variable Blanding's Turtle Emydoidea blandingii
Bog Turtle Glyptemys muhlenbergii
Common Map Turtle Graptemys geographica
Common Musk Turtle Sternotherus odoratus
Eastern Spiny Softshell Apalone spinifera
Fowler's Toad Bufo fowleri
Spotted Turtle Clemmys guttata

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Northern species

Two species were identified as having the southern edge of their range in northern New York (Table 3).
The New York distribution maps and range maps for these species follows.

Table 3. Herpetofauna species with the edge of their range in the northern part of New York State.
Common name Scientific name Type
Mink Frog Rana septentrionalis amphibian - frog
Western Chorus Frog Pseudacris triseriata amphibian - frog

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Mink Frog (Rana septentrionalis)

Description: This frog measures 4.8 -7.0 cm long and has a mottled or spotted dorsal pattern. The skin
produces a mink-like odor (or rotten onions) when the frog is rubbed.

Habitat: Found along streams and rivers but prefers borders of ponds and lakes.
(Conant & Collins 1991)

Figure 2. The earliest observations of Mink Frog within each USGS quadrangle. Quads with only more
recent observations have larger dot sizes.

Figure 3. Range map for Mink Frog compiled by IUCN, Conservation International,
NatureServe, and collaborators (NatureServe 2010).

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Western Chorus Frog (Pseudacris triseriata)

Description: A small frog measuring 1.9 – 3.9 cm long. The back is usually pale gray with three dark
stripes down the back and a wide dark stripe down each side of the body passing through the eye.

Habitat: Found in a variety of habitats, some dry and altered by human activities. Originally occurring in
prairies but has expanded its range into farm lands. May also inhabit damp meadows and marshes.
(Conant & Collins 1991, Shearwater Marketing Group 2007, NatureServe 2010)

Figure 4. The earliest observations of Western Chorus Frog within each USGS quadrangle. Quads with
only more recent observations have larger dot sizes.

Figure 5. Range map of Western Chorus Frog (IUCN Red list of Threatened Species 2010). Data source:
IUCN, Conservation International & NatureServe.

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Southern species

Nine species were identified as having the northern edge of their range in the southern half of New York
(Table 4). The New York distribution maps and range maps for these species follow.

Table 4. Herpetofauna species with the edge of their range in southern New York.
Common Name Scientific name Type
Eastern Box Turtle Terrapene c. carolina reptile - turtle
Eastern Hellbender Salamander Cryptobranchus a. alleganiensis amphibian - salamander
Eastern Redbelly Turtle Pseudemys rubriventris reptile - turtle
Longtail Salamander Eurycea l. longicauda amphibian - salamander
Northern Black Racer Coluber c. constrictor reptile - snake
Northern Red Salamander Pseudotriton r. ruber amphibian - salamander
Red-eared Slider Trachemys scripta elegans reptile - turtle
Southern Leopard Frog Rana sphenocephala amphibian - frog
Timber Rattlesnake Crotalus horridus reptile - snake

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