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EffEcts of ArtificiAl Night lightiNg oN AmphibiANs ANd rEptilEs
iN UrbAN ENviroNmENts
Gad Perry1, Bryant W. Buchanan2, Robert N. Fisher3,
Mike Salmon4, and Sharon E. Wise2
Abstract — Amphibians and reptiles have evolved with natural lighting cycles. Consequently, alteration of natural
variation in diurnal and nocturnal light intensities and spectral properties has the potential to disrupt their physiology,
behavior, and ecology. We review the possible effects of night lighting on many species of amphibians and reptiles,
noting that few studies of the consequences of articial lights to amphibians and reptiles have been conducted to
date. The one exception is the information available on the negative impacts of articial lights on hatchling sea
turtles, which have received considerable coverage in both scientic and popular media. In many studies that might
be relevant, researchers have not recorded the illumination or irradiance at which experiments were conducted. We
identify light pollution as a serious threat that should be considered as part of planning and management decisions
in the maintenance or conservation of urban areas containing amphibians and reptiles. However, we consider it too
early to precisely gauge the effects of articial night lighting on other taxa found in light-polluted environments or
provide specic management recommendations, beyond pointing out the urgent need for more information.
Key words — Activity Pattern, Amphibians, Behavior, Conservation, Ecology, Invasive Species, Light Pollution,
Night Lighting, Photopollution, Physiology, Reptiles, Suburban, Urban
Chapter
16
© 2008 by the Society for the Study of Amphibians and Reptiles
Urban Herpetology. J.C. Mitchell, R.E. Jung Brown, and B. Bartholomew, editors
Herpetological Conservation 3:xx-xx.
1Department of Natural Resources Management, Box 42125, Texas Tech University, Lubbock, TX 79409, USA
2Department of Biology, Utica College, 1600 Burrstone Rd., Utica, NY 13502, USA
3U.S. Geological Survey, Biological Resources Discipline, San Diego Field Station, 4165 Spruance Road, Suite 200, San Diego, CA
92101, USA
4Department of Biological Sciences, Florida Atlantic University, PO Box 1096, 777 Glades Rd., Boca Raton, FL 33431, USA
239
Conservation biologists have long been concerned about
anthropogenic effects on species and environments. ere
is good reason for herpetologists to share this concern: both
amphibians and reptiles are declining worldwide (e.g., Alford
and Richards 1999; Gibbons et al. 2000). Much work has
focused on habitat loss and the consequences of water and air
pollution, particularly on amphibians. Other anthropogenic
impacts, such as light pollution, remain poorly studied and
are of concern for urban herpetofauna (defined here as those
species that are present within or adjacent to urbanized areas).
Light pollution is a by-product of anthropogenic outdoor illu-
mination from sources such as street lighting, sports arenas,
and porch lights (e.g., Dawson 1984). When discussed in the
context of adverse effects on wildlife, light pollution is also
known as photopollution (Verheijen 1985). Its effects on her-
petofauna are the focus of this chapter.
Five decades ago, Verheijen (1958) documented illumina-
tion patterns produced by lighting devices in urban habitats.
e abnormal lighting patterns from these artificial sources
resulted in locally elevated contrast in brightness between
lighted and background areas which attracted invertebrates, a
phenomenon known as “light trapping” (Robinson and Rob-
inson 1950). Artificial lighting has become much more perva-
sive since 1958, affecting most of the world’s urban areas and
adjacent habitats (Cinzano et al. 2001; Longcore and Rich
2004). Street and security lights can be more than one million
times brighter than natural ambient illumination (S. Wise and
B. Buchanan unpubl. data). Additionally, skyglow, caused by
240
Pe r r y e t a l .
reflection of artificial night lights from clouds, may increase
nocturnal ambient illumination indirectly in less urban areas
near cities (Cinzano et al. 2001). Sources of light pollution
are often referred to as “night lighting,” and the relatively new
habitat created by the presence of artificial lights has some-
times been termed the “night-light niche” (Garber 1978).
With the exception of negative consequences for sea turtles,
data on the effects of night lighting on amphibians and rep-
tiles are uncommon. A recent book (Rich and Longcore 2006)
focuses on many ecological aspects of light pollution. To avoid
duplication, this review provides an updated synthesis of
information we presented separately there (Buchanan 2006;
Perry and Fisher 2006; Salmon 2006; Wise and Buchanan
2006). We focus on what little is known about the relation-
ship between artificial lighting and urban herpetofauna and
suggest areas that require further work. Special attention is
paid to taxa that appear to be at greatest risk of being effected:
species that are edificarian, feed at lights (or are simply posi-
tively phototactic), inhabit permanent and ephemeral ponds
(parks, ditches), or are found in greenbelts or habitat reserves
in or near city limits that are affected by skyglow or glare.
Roads that connect urban areas, many of them illuminated
by fixed lights in addition to vehicle headlights, may also have
effects on species occurring nearby (Outen 2002; Spellerberg
2002), although few papers address this problem (e.g., Baker
1990; Mazerolle et al. 2005). In this chapter, we document the
apparently positive (i.e., population-increasing) consequences
of night lighting on some species and discuss effects that are
clearly or possibly negative for others.
Taxonomic P r e f ac e
Information presented in the body of this chapter is arranged
by habitat. However, some taxon-specific information pertains
across habitats and is presented here. We use standard English
names for large, well-recognized clades, but prefer scientific
names when discussing specific species.
Salamanders — Salamanders are often nocturnal or crepuscu-
lar, with activity patterns regulated by photoperiod (reviewed
in Wise and Buchanan 2006). Many species that have been
studied are negatively phototropic or phototactic, although
some species may show ontogenetic shifts in behavior, exhib-
iting positive phototaxis as larvae and negative phototaxis as
adults (reviewed in Wise and Buchanan 2006). Artificial night
lighting may affect physiology and behavior by (1) increasing
ambient illumination, (2) lengthening photoperiod, and (3)
varying the spectral properties of ambient light. Most stud-
ies of the effect of artificial light on salamanders have been
conducted in the laboratory and focus on hormone levels or
thermoregulation. ese laboratory results, the basis for much
of the information below, are important for generating field-
testable hypotheses that may explain how artificial night light-
ing affects salamander populations in natural habitats.
Frogs — Frogs may be exposed to extreme changes in natural
lighting patterns in urban environments. Few data exist that
demonstrate direct effects of lighting on frogs, but many indi-
rect effects are likely (Buchanan 2006). Adults of most taxa
conduct the majority of their foraging and reproductive activi-
ties under twilight or nocturnal conditions. Eggs and larvae
typically develop in aquatic environments, where they may
be exposed to artificial illumination. Unfortunately, very few
experimental data exist on the effects of artificial illumination
on frogs in natural environments. Consequently, most of the
data presented in this chapter have been extracted from papers
dealing with the general effects of light on the physiology or
behavior of frogs.
Caecilians — As with most subterranean taxa, relatively little is
known about the biology of caecilians (Gower and Wilkinson
2005). Although many caecilians are of conservation con-
cern, night lighting seems unlikely to be a significant cause
of population decline, because these animals spend so little
time above-ground and possess such poor eyesight. We have
found no information to suggest otherwise and therefore do
not discuss caecilians in the sections that follow.
Tuataras — e remaining range of this taxon is limited, and
does not overlap major population centers. us, night light-
ing is unlikely to affect populations. e current recovery plan
(Gaze 2001) does not refer to lights as a source of concern,
and as we have found no information to suggest otherwise, do
not discuss tuataras in the sections that follow.
Crocodilians — Relatively few crocodilians occur in abundance
in urban areas. When they do, as in parts of Florida, USA,
and Darwin, Australia (Nichols and Lentic 2008), they are
often considered a source of concern in terms of human safety,
rather than a target for conservation efforts. Perhaps because
of this bias, we have been unable to locate evidence of possible
effects of night lighting on these organisms. us, no informa-
tion on crocodilians is presented in this chapter. Given that
most crocodilian species are under some degree of threat and
that urban sprawl is likely to bring more of them into contact
with humans and night lighting, we feel that studies to explore
these effects are urgently needed.
Turtles — Marine turtles are diving specialists (Lutcavage and
Lutz 1999) whose vision is adapted to finding food, locating
mates, and avoiding predators underwater. Seawater differen-
tially absorbs both the shorter (UV, violet) and longer (yellow
to red) light wavelengths, while best transmitting wavelengths
between 450–500 nm (blue-green to green). Some turtles
have spectral sensitivities that are “tuned” (most sensitive) to
the latter; sensitivity declines rapidly as wavelength increases
(Witherington 1992a; Lohmann et al. 1997; J. Gocke, M.
Salmon, and K. Horch unpubl. data). Negative influences
of light pollution on sea turtles, especially those of artificial
lights near beaches on the seaward locomotion of hatchlings,
241
effects o f a rtificial l i g h t s o n h e r P s
have been well-studied (reviewed in Witherington and Martin
1996), and have led to the only attempts we are aware of to
reduce such negative influences. However, the attention given
to sea turtles has not resulted in investigations of other turtles.
We suggest that field research on non-marine turtles is another
area that needs to be addressed.
Lizards — Lizards are often terrestrial and can be either diurnal
or nocturnal. More anecdotal information about the effects of
night lighting on lizards is available than for any other group
(Perry and Fisher 2006). Although this effort has identified
some intriguing preliminary patterns (e.g., positive effects for
invading species, discussed below), the lack of experimental or
systematic observational data is a source of concern.
Snakes — Snakes can be either diurnal or nocturnal, and some
species show an ontogenetic switch (Clarke et al. 1996). No
studies directly link artificial light to positive or negative effects
on snake populations. However, declines have been noted in
snake populations in many populated regions, making such
work very timely. Perry and Fisher (2006) discussed possible
positive predator-prey interactions between snakes and their
prey, such as geckos, that are attracted to artificial lights. ey
also reviewed the probable negative predator-prey interactions
associated with prey, such as the apparent decline of hetero-
myid rodents due to artificial lights, and increased exposure
to snake predators. Snakes generally elicit a negative response
in the general public, placing them at a special disadvantage
in urban areas.
effecTs o f lighT i n urban h a b i Ta T s
Although irradiance (defined as the density of radiant flux
on a surface and typically measured over 180 degrees in units
of W/cm2) is the more appropriate measure of light intensity
to use when describing light levels, we often refer to illumina-
tion (lux, lumen/m2), because it is more commonly reported
in the literature, making for easier comparisons.
Urban Cores — In this section, we focus on species found
within or near human dwellings (i.e., edificarian species). Taxa
common in urban cores are often familiar to many; some of
them have had a long history of co-residence with humans.
Although the number of species capable of surviving close to
humans is low, edificarian species can reach high densities in
their adopted habitat. Responses of edificarian amphibians
and reptiles to artificial lights are well documented (Tables 1,
2), but ecological consequences remain much less obvious.
Salamanders — Few salamanders are found in urban cores.
However, Garden Slender Salamanders (Batrachoseps major),
California Slender Salamanders (B. attenuatus), and Arboreal
Salamanders (Aneides lugubris) often occur around houses
or along rock walls in California, USA (Cunningham 1960;
Petranka 1998). We have not been able to find any informa-
tion on effects that night lighting might have on such species.
Frogs — Some species of frogs commonly associate with edifi-
carian habitats, including several species that feed on insects at
lights (Table 2). Such species are typically only active at night,
normally foraging under low ambient illumination (Wool-
bright 1985; Buchanan 1992). Some nocturnal frogs, such as
the widely introduced Cane Toads (Bufo marinus), regularly
forage under enhanced illumination near buildings (Table 2).
Many nocturnal frogs show positive phototaxis (Jaeger and
Hailman 1973), and laboratory studies have demonstrated that
enhanced lighting can facilitate foraging in edificarian species
(Larsen and Pedersen 1982; Buchanan 1998). However, it is
unclear whether frogs are attracted to the increased abundance
of insects available at lights, the light itself, or a combination
of the two. How much light or what illumination differential
is necessary to elicit this effect also remains unknown.
Although additional foraging opportunities can be benefi-
cial, frogs aggregating at lights may also experience increased
mortality. For example, Baker (1990) suggested that frogs
feeding under streetlights are particularly susceptible to being
killed by automobiles. In addition, radical and rapid changes
in illumination can reduce visual sensitivity and require hours
for complete light adaptation (Cornell and Hailman 1984).
e frog eye tends to adapt to the brightest available source
of light (Fain et al. 2001). Once they are light-adapted, frogs
moving through areas with different ambient illuminations
may suffer reduced visual capabilities, particularly when mov-
ing into shadows cast by artificial lights (Cornell and Hailman
1984; Buchanan 1993; Fain et al. 2001).
Table 1. Non-nocturnal amphibians and reptiles reported to use the night-light niche.
Species Location Source
Lizards
Geckos (Gekkonidae)
Gonatodes humeralis Peru Dixon and Soini 1975
Gonatodes vittatus Trinidad Quesnel et al. 2002
Lygodactylus capensis South Africa V. Egan unpublished
Phelsuma laticauda Hawaii Perry and Fisher 2006
Phelsuma madagascariensis Madagascar García and Vences 2002
242
Pe r r y e t a l .
Species Location Source
Sphaerodactylus cinereus Florida, USA J. Lazell unpublished
Haiti J. Lazell unpublished
Sphaerodactylus elegans Florida, USA Meshaka et al. 2004
Sphaerodactylus dicilis Hispaniola R. Powell unpublished
Sphaerodactylus macrolepis Guana Island, BVI Perry and Lazell 2000
Sphaerodactylus sputator Anguilla Howard et al. 2001
Anoles (Iguanidae)
Anolis aeneus Grenada R. Powell unpublished
Anolis bimaculatus St. Eustatius R. Powell unpublished
Anolis brevirostris Hispaniola Bowersox et al. 1994
Anolis carolinensis Hawaii Perry and Fisher 2006
Mississippi, USA J. Lazell unpublished
Texas, USA McCoid and Hensley 1993
Anolis cristatellus Dominican Republic Schwartz and Henderson 1991
Guana Island, BVI Perry and Lazell 2000
Puerto Rico Garber 1978
Anolis cybotes Hispaniola Henderson and Powell 2001
Anolis distichus Hispaniola R. Powell unpublished
Anolis gingivinus St. Maarten Powell and Henderson 1992
Anguilla Hodge et al. 2003
Anolis leachii Antigua Schwartz and Henderson 1991
Anolis lineatopus Jamaica Rand, 1967
Anolis luteogularis Cuba J. Losos, unpublished
Anolis marmoratus Guadeloupe Powell and Henderson 1992
Anolis richardii St. George’s, Grenada Perry and Fisher 2006
Anolis sabanus Saba Powell and Henderson 1992
Anolis sagrei Bahamas Schwartz and Henderson 1991
Florida, USA Meshaka et al. 2004
Anolis schwartzi St. Eustatius Powell et al. 2005
Anolis trinitatus St. Vincent R. Powell unpublished
Young Island R. Powell unpublished
Other iguanids (Iguanidae)
Agama agama Cameroon Böhme 2005
Gabon Pauwels et al. 2004
Basiliscus basiliscus Costa Rica A. Vega unpublished
Leiocpehalus carinatus Florida, USA Meshaka, in preparation
Tropidurus plica (= Plica plica) Trinidad Werner and Werner 2001
Skinks (Scincidae)
Cryptoblepharus poecilopleurus Cocos Island, Guam McCoid and Hensley 1993
Lamprolepis smaragdina Pohnpei Perry and Buden 1999
Snakes
Racers (Colubridae)
Alsophis portoricensis Guana Island, BVI Perry and Lazell 2000
Table 1. Continued
243
effects o f a rtificial l i g h t s o n h e r P s
Table 2. Nocturnal amphibians and reptiles reported to use the night-light niche.
Species Location Source
Frogs
Toads (Bufonidae)
Bufo americanus Oklahoma, USA J. Lazell unpublished
Bufo bufo England Baker 1990
Bufo cognanus Texas, USA S. Rideout unpublished
Bufo gutturalis South Africa V. Egan unpublished
Bufo maculatus Cameroon Böhme 2005
Bufo marinus Costa Rica A. Vega unpublished
Florida, USA Meshaka et al. 2004
Guadeloupe Henderson and Powell 2001
Hawaii, Fiji, American Samoa R. Fisher unpublished
Bufo melanostictus China Lazell 2002
Bufo terrestris Florida, USA W. Meshaka unpublished
Bufo woodhousii Oklahoma, USA J. Lazell unpublished
Bufo viridis Europe Balassina 1984
Schismaderma carens Tanzania V. Egan unpublished
Rain frogs (Leptodactylidae)
Eleutherodactylus coqui Puerto Rico Henderson and Powell 2001
Eleutherodactylus johnstonei Saba, Netherlands Antilles Perry 2006
Treefrogs (Hylidae)
Hyla cinerea Florida, USA Goin 1958
Mississippi and Louisiana, USA B. Buchanan unpublished
Hyla femoralis Florida, USA W. Meshaka unpublished
Hyla gratiosa Florida, USA W. Meshaka unpublished
Hyla squirella Florida, USA Goin and Goin 1957
Mississippi and Louisiana, USA B. Buchanan unpublished
Osteopilus septentrionalis Anguilla Henderson and Powell 2001
Guana, British Virgin Islands G. Perry, in MS
Florida, USA Carr 1940
Scinax eleochroa Costa Rica A. Vega unpublished
Old World treefrogs (Rhacophoridae)
Chiromantis xerampelina South Africa V. Egan unpublished
Lizards
Geckos (Gekkonidae)
Afrogecko porphyreus South Africa E. Baard unpublished
Bunopus tuberculatus United Arab Emirates Perry and Fisher 2006
Cosymbotus platyurus Southeast Asia Case et al. 1994
Cyrtopodion scabrum Jordan Disi et al. 2001
Gekko chinensis China J. Lazell unpublished
Gekko gecko China J. Lazell unpublished
Florida, USA W. Meshaka unpublished
Thailand R. Fisher unpublished
244
Pe r r y e t a l .
Species Location Source
Gekko subpalmatus China J. Lazell unpublished
Philippines J. Lazell unpublished
Indonesia J. Lazell unpublished
Gehyra mutilata China J. Lazell unpublished
Hawaii J. Lazell unpublished
Sapwuahk Atoll Buden 2000
Gehyra oceanica Sapwuahk Atoll Buden 2000
Pacic Region R. Fisher unpublished
Hemidactylus brookii China J. Lazell unpublished
Hemidactylus bowringi China J. Lazell unpublished
Hemidactylus aviviridis Egypt Ibrahim and Ghobashy 2004
United Arab Emirates Perry and Fisher 2006
Hemidactylus frenatus Australia Cogger 1979:179
Costa Rica Savage 2002:484-485
Florida, USA W. Meshaka unpublished
Guam G. Perry unpublished
Hawaii Case et al. 1994
Hemidactylus garnotii Costa Rica Savage 2002:484-485
China J. Lazell unpublished
Pacic Region R. Fisher unpublished
Florida, USA Meshaka 2000
Hemidactylus haitianus
(recently renamed H. angulatus)Dominican Republic Bowersox et al. 1994
Hemidactylus mabouia Anguilla Howard et al. 2001
Brazil Perry and Fisher 2006
Cameroon Böhme 2005
Gabon Pauwels et al. 2004
Dutch Antilles Powell and Henderson 1992
Florida, USA Meshaka 2000
Guana Island, BVI G. Perry unpublished
Puerto Rico R. Powell unpublished
South Africa V. Egan unpublished
Venezuela Fuenmayor et al. 2005
Hemidactylus persicus United Arab Emirates Perry and Fisher 2006
Hemidactylus turcicus Israel Werner 1966
Egypt A. Ibrahim unpublished
Jordan Disi et al. 2001
United Arab Emirates Perry and Fisher 2006
USA: Alabama, Florida, and Mis-
sissippi
Nelson and Carey 1993
Texas, USA G. Perry unpublished
Hemiphyllodactylus typus Pacic Region R. Fisher unpublished
Homopholis wahlbergi South Africa V. Egan unpublished
Table 2. Continued
245
effects o f a rtificial l i g h t s o n h e r P s
Species Location Source
Lepidodactylus lugubris Costa Rica Savage 2002:486
Guam G. Perry unpublished
Hawaii Case et al. 1994
Sapwuahk Atoll Buden 2000
Nactus pelagicus South Pacic Perry and Fisher 2006
Pachydactylus bibronii Namibia Perry and Fisher 2006
South Africa E. Baard unpublished
Pachydactylus turneri Namibia Perry and Fisher 2006
South Africa V. Egan unpublished
Ptyodactylus guttatus Israel Werner 1965
Ptyodactylus hasselquistii Israel Y.L. Werner unpublished
United Arab Emirates Perry and Fisher 2006
Ptyodactylus puiseuxi Israel Y.L. Werner unpublished
Tarentola annularis Egypt Ibrahim 2004
Tarentola mauritanica Egypt A. Ibrahim unpublished
Libya Ibrahim and Ineich 2005
Thecadactylus rapicauda Anguilla R. Powell unpublished
Dominica J. Lazell unpublished
Necker, BVI J. Lazell unpublished
Trinidad Kaiser and Diaz 2001
Snakes
Racers (Colubridae)
Lamprophis fuliginosus Namibia Cunningham 2002
Boiga irregularis Guam Perry and Fisher 2006
Papua New Guinea Perry and Fisher 2006
Solomon Islands Perry and Fisher 2006
Table 2. Continued
Turtles — Some terrestrial turtles, such as Box Turtles (genus
Terrapene) are known to inhabit urban cores (Dodd 2001).
Most of these species are diurnal and could conceivably be
affected if night lighting extends their activity period or dis-
turbs their nocturnal rest. Whether such an effect actually
occurs remains unknown.
Lizards — Night lighting can benefit some urban lizards.
Species that are not normally active after dark, especially ano-
lis lizards, have been observed foraging or being active near
artificial lighting at night (Table 1), taking advantage of the
“night-light niche” (Garber 1978). Normally nocturnal spe-
cies, especially members of the family Gekkonidae, have also
been documented around night lights (Table 2). At least some
of these taxa are also known to occasionally be active during
the day (McCoid and Hensley 1993; Teynié et al. 2004).
Presumably, the attraction of invertebrates to artificial lights
attracts lizards because of the greater quantity of food and the
increased predictability of finding prey. Intriguingly, the work
of Werner (1990) suggests that artificial lights can also provide
basking sites, and thus a second important resource, for lizards
(and possibly other amphibians and reptiles). Observations
from Egypt (Ibrahim 2004; Ibrahim and Ghobashy 2004)
suggest this may be a broad pattern, especially in winter, but
additional studies are desirable.
Negative effects of lights on non-introduced urban lizards
have not been documented, but some species are more likely
to take advantage of the presence of lights, and asymmetric
competition can cause locally negative effects for other taxa.
e best-documented example is the interaction between two
introduced geckos, the Common House Gecko Hemidactylus
frenatus and the Mourning Gecko Lepidodactylus lugubris, in
the Pacific. Although H. frenatus has negatively affected popula-
tions of L. lugubris and the Oceanic Gecko Gehyra oceanica in
some lighted locations (Case et al. 1994), the two species appear
to coexist in native and less-disturbed habitats (Case et al. 1994)
and on other lighted structures (Perry and Fisher 2006).
Taxa that would not normally interact might nonetheless
meet where artificial lights are available. Perry and Fisher
(2006) reported a more extreme example from Hawaii.
246
Pe r r y e t a l .
Hemidactylus frenatus (nocturnal), the Gold Dust Day Gecko
Phelsuma laticauda (a diurnal gecko), and the green anole A.
carolinesis (also diurnal) sometimes forage together at the same
light source, and may compete for food resources. Ironically,
all three are not native to Hawaii, and their ranges do not
naturally overlap anywhere. Observations conducted in 2007
indicate that P. laticauda was successful in competing for these
habitats, at least in the area around Kona, Hawai’i, where it
now dominates both the diurnal and nocturnal lizard com-
munities (R. Fisher, unpub.). In a different example, Perry and
Lazell (2000) reported that Anolis cristatellus forages at artifi-
cial lights in the British Virgin Islands. Its predator, the snake
Alsophis portoricensis (Puerto-Rican Racer), was also observed
at the same lights. ese species would normally interact dur-
ing the day, but such additional interactions are of interest
for two reasons. First, if common enough, added interactions
can exacerbate normal predation effects. Second, and more
importantly, this example shows that night lighting can affect
more than a single species at a time, perhaps allowing species
to interact that would otherwise not do so and possibly creat-
ing novel food webs. More severe or pervasive consequences
might occur when night lighting exposes native species to
competition with or predation by native or introduced species
with which they would not normally interact.
Snakes — e effects of night lighting are difficult to separate
from other problems that snakes face in urban environments,
such as persecution. Only two published reports have been
found of nocturnal snakes foraging under lights (Table 2).
Other nocturnal species, such as the Brahminy Blind Snake
Ramphotyphlops braminus, are found near houses in tropical
areas and in cities where they have become established, but
what effect lights have on their populations is not known.
ur b a n W a T e r b odies and greenbelTs
Many cities and towns have areas of natural or semi-natu-
ral aquatic or terrestrial habitats, such as city parks and water
runoff storage areas, within or just outside their limits. ese
are typically managed for aesthetics, recreation, and/or flood
control. ey may be connected to each other by corridors
or isolated, and the intensity of management can range from
heavy (e.g., channeled streams) to very low. In these areas,
skyglow may chronically increase ambient illuminations to
levels substantially greater than normal nocturnal light levels
(Buchanan 2006; Cinzano et al. 2001). As a result, artificial
illumination around urban ponds can be brighter than even
the brightest natural nocturnal light levels. For example, noc-
turnal light intensity around Utica Marsh in Utica, New York
was measured at 0.1–1 lux (S. Wise and B. Buchanan unpubl.
data), equivalent to illuminations at dawn or dusk. High-den-
sity urban cores are typically surrounded by less developed
areas (e.g., agriculture, waterways, and greenbelts). In such
areas, human density gradually decreases with distance from
the core and species absent from the city core are often pres-
ent here. Despite greater diversity, however, these areas remain
influenced by the urban matrix in which they are embedded
and the resulting light pollution.
Salamanders — Salamanders, such those of the genera
Ambystoma (Mole Salamanders) and Notophthalmus (Eastern
Newts), are commonly found in ponds and surrounding ter-
restrial habitats within or near urban areas. Completely ter-
restrial taxa, such as those of the genus Plethodon (Woodland
Salamanders), may be found in large wooded city parks and
greenbelts. Where ponds are located near roadways, salaman-
ders can be subject to very high probabilities of automobile
impacts when crossing roads during nocturnal activity (Fah-
rig et al., 1995; Hels and Buchwald 2001; Mazerolle 2004).
Most spotted salamanders (Ambystoma maculatum) and blue-
spotted salamanders (Ambysotoma laterale) respond to distur-
bance and lights from approaching automobiles by halting
their movements, perhaps further increasing the probability
of automobile-induced mortality by increasing the time that
salamanders spend on the roadway (Mazerolle et al. 2005).
e physiology and behavior of salamanders are influenced
by a variety of biotic and abiotic factors, including ambient
light. Introduction of artificial light during normally dark
periods can disrupt the production of melatonin, a hormone
responsible for many aspects of photoperiodic behavior and
physiology (Vanecek 1998). Common Mudpuppy (Necturus
maculosus) aquatic adults kept on a 12L:12D photoperiod
exhibited higher plasma melatonin levels during the dark
phase than during the light phase (Rawding and Hutchison
1992). When the photoperiod was reversed, melatonin pro-
duction was also reversed. Aquatic adults of the Eastern Tiger
Salamander Ambystome tigrinum also had significantly higher
plasma levels of melatonin during scotophase (the dark period
of a day-night cycle) than during photophase (the light period
of a day-night cycle) (Gern and Norris 1979). Gern et al.
(1983) found that A. tigrinum kept under constant light (a
condition that can occur under bright point sources of arti-
ficial night lighting) did not show significant differences in
plasma levels of melatonin during photophase and scotophase
as they would under natural lighting conditions. Although not
tested statistically, levels of melatonin during scotophase were
similar to levels during photophase for salamanders kept on a
regular 12L:12D photoperiod.
Melatonin has multiple effects in amphibians, including
reducing tolerance to high temperatures and lowering body
temperature (Erskine and Hutchison 1982; Hutchison et al.
1979). One prediction, therefore, is that decreased nocturnal
plasma melatonin levels will cause higher metabolic rates.
Whitford and Hutchison (1965) compared physiological
functions of terrestrial adults of Spotted Salamander (A. macu-
latum) kept on a 16L:8D photoperiod to those kept on an
8L:16D photoperiod. As predicted, animals kept on a 16L:8D
photoperiod had significantly higher pulmonary, cutaneous,
and total rates of O2 consumption and higher cutaneous
and total rates of CO2 production (Whitford and Hutchison
247
effects o f a rtificial l i g h t s o n h e r P s
1965). Wise and Buchanan (2006) therefore hypothesized
that artificially increasing the length of photophase through
night lighting may disrupt normal cyclical changes in meta-
bolic rates, changing the energy demands of salamanders. is
effect could become problematic during periods of low food
availability or when energetic demands are especially high,
such as during egg production or periods of drought.
e diel pattern of vertical migration exhibited by larval
salamanders (genus Ambystoma: A. jeffersonianum (Jefferson
Salamander), A. opacum, A. talpoideum (Mole Salamander),
and A. tigrinum) is influenced by ambient light, temperature,
competition, and predation risk (Anderson and Graham 1967;
Stangel and Semlitsch 1987). Anderson and Graham (1967)
observed that A. opacum exhibited more activity on overcast
days and less vertical migration on bright nights. Interruption
of vertical migration may reduce size at metamorphosis or sur-
vival (Semlitsch 1987).
Changes in light intensity during scotophase as a result of
artificial night lighting can also affect other behaviors, such as
foraging. Buchanan (unpubl. data) tested adult Red-backed
Salamanders (Plethodon cinereus) in the laboratory, in the
absence of olfactory cues but under a range of illuminations
(complete darkness, 10-5, 10-4, or 10-3 lux). Salamanders ori-
ented toward prey sooner at higher ambient illuminations,
indicating improved visually-based foraging ability with higher
light levels. Although increased ambient light may allow sala-
manders to see prey better, it can also delay the nocturnal
foraging activity of P. cinereus, which typically emerge from
the leaf litter approximately 1–2 h after dark (B. Buchanan
and S. Wise unpubl. data; Fig. 1). Buchanan and Wise con-
ducted forest censuses 1–2 h after sunset in six dark (no artifi-
cial illumination; 10-4 lux) and six lighted (with white holiday
lights; 10-2 lux, equivalent to bright moonlight) transects.
Fewer salamanders were active in the lighted transects than in
the unlighted transects during the census. B. Buchanan and
S. Wise (unpubl. data) hypothesized that delayed emergence
may reduce the length of time salamanders are able to forage,
especially on dry nights, when reduced humidity decreases the
amount of time spent foraging (Keen 1984).
Agonistic behavior is also affected by nocturnal ambi-
ent illumination. Adults of P. cinereus are territorial, guard-
ing cover objects that provide access to food, moisture, and
potentially mates (Mathis et al. 1995). In the laboratory, B.
Buchanan (unpubl. data) examined the threat displays exhib-
ited by territorial residents towards intruding salamanders
under different levels of illumination (complete darkness,
10-4, or 10-2 lux). Residents used more visual displays as light
intensities increased. Presumably, visual threat displays are
energetically costly to produce (Wise and Jaeger 1998); thus,
increased use of visual displays with increased ambient illu-
mination may negatively affect energy budgets. On the other
hand, increased visibility may also allow individuals to assess
better the outcome of agonistic interactions, thereby reducing
the probability of contests escalating to overt aggression and
injury (Jaeger 1981).
Spectral properties of light may affect migration to and
from ponds. Metamorphosed juvenile Red-spotted Newts
(Notophthalmus viridescens) migrate from their natal ponds to
nearby forests a few months after hatching and return to their
natal ponds as adults. Adults also leave the ponds during peri-
ods of drought or when ponds freeze (Petranka 1998). ese
salamanders use a light-dependent magnetic compass (Phil-
lips et al. 1995) involving extraocular photoreceptors (Adler
1970; Deutschlander et al. 1999) for navigation. Phillips and
Borland (1992a,b,c, 1994) demonstrated experimentally that
orientation and homing behavior were disrupted by mono-
chromatic, long-wavelength light (yellow spectrum, especially
550–600 nm). Common outdoor lights emit light at 540–630
nm (Massey et al. 1990). eir use, therefore, could negatively
affect the ability of N. viridescens, and perhaps other species of
salamanders that use a similar light-dependent magnetic com-
pass, to navigate to home ponds for breeding. us, spectral
properties of artificial night lighting should be considered as
Fig. 1. Activity of Plethodon cinereus (Red-backed Salaman-
der) during a representative night census (from dusk until
dawn, 2100 – 0700 h, 1-2 July 2003) of two 50 x 1 m tran-
sects (Buchanan and Wise, unpubl. data). The study was
conducted at Mountain Lake Biological Station, University
of Virginia, Giles County, VA. Plotted are the numbers of
salamanders detected on the leaf litter or vegetation (n),
the mean illumination from the 4 cardinal directions (l),
temperature (°), and percent relative humidity (®) for each
sampling period.
248
Pe r r y e t a l .
part of conservation or management efforts in urbanized habi-
tats containing semi-aquatic salamanders.
Frogs — Frogs are typically aquatic breeders, and in urban
settings they are likely to use both ephemeral breeding sites
(e.g., ditches) and permanent sites (e.g., ponds or streams).
Such sites are frequently exposed to increased light levels due
to roadway lighting and skyglow (Buchanan 2006). Effects
of altered lighting may be seen as early as during embryonic
growth and larval development. Decreasing the duration of
scotophase slowed growth in larval Painted Frogs Discoglossus
pictus (Gutierrez et al. 1984) and African Clawed Frogs Xeno-
pus laevis, causing the latter to metamorphose at a smaller size
(Delgado et al. 1987; Edwards and Pivorun 1991). Conversely,
constant lighting accelerated larval development in Northern
Leopard Frogs, Rana pipiens (Eichler and Gray 1976). us,
artificial night lighting has the potential to affect time to meta-
morphosis or size at metamorphosis.
e behavior and physiology of tadpoles may also be
affected by night lighting. For example, larval American Toads
(Bufo americanus) use photoperiodic cues to thermoregulate
behaviorally (Beiswenger 1977) and vertical migration in Xen-
opus laevis larvae is dependent upon changes in illumination
(Jamieson and Roberts 2000). Exposure at night to artificial
light for as little as 1 min can disrupt production of precursors
required for larval melatonin production (Lee et al. 1997),
which may in turn have important effects on physiological
performance (Vanecek 1998). For example, X. laevis larvae
exposed to constant lighting did not experience normal diel
patterns of color change (Binkley et al. 1988).
Adult frogs living in greenbelt or park areas, like those of
many species, would traditionally be active at very low envi-
ronmental illuminations (reviewed in Buchanan 2006), and
may thus be affected by artificial night lighting. Species such as
the Western Tailed Frog Ascaphus truei, normally active only at
the darkest natural nocturnal illuminations (Hailman 1982),
are likely to be influenced when environmental illuminations
increase to levels at which the frogs typically seek refugia.
Artificial night lighting can disrupt foraging, fat storage, and
growth in adult frogs (e.g., in Fowler’s Toad B. fowleri, Bush
1963). Reproductive behavior is also sensitive to changes in
illumination. For example, calling males of Panamanian Cross-
banded Treefrogs Smilisca sila exhibit illumination-dependent
changes in anti-predator behavior under natural conditions
(da Silva Nunes 1988). In another example, females of the
Tungara Frog (Physalaemus pustulosus) become less likely to
exhibit mate choice at higher ambient illuminations (Rand
et al. 1997), and vary their oviposition behavior in response
to changes in illumination (Tárano 1998). Other nocturnally
breeding species, such as the Squirrel Treefrog Hyla squirella
(Taylor et al. 2007) and the Sarayacu Treefrog H. parviceps
(Amézquita and Hödl 2004), use visual cues in mate choice
and male-male competition. Artificial lighting may allow these
and other visually-based behaviors to occur at uncharacteristic
times or intensities (Buchanan 2006).
Frogs moving across roadways while foraging or breeding
have a high probability of being killed by automobiles (Fahrig
et al., 1995; Hels and Buchwald 2001; Mazerolle 2004). Many
frogs are primarily active at night, and the moving lights of
oncoming cars create cycles of increasing and decreasing illu-
mination that may make dark adaptation difficult. Buchanan
(1993) found that rapid increases in illumination similar to
that produced by oncoming traffic slow visual foraging in the
Gray Treefrog (H. chrysoscelis). Mazerolle et al. (2005) similarly
found that nocturnally active American toads (B. americanus),
spring peepers (P. crucifer), green frogs (R. clamitans), and
wood frogs (R. sylvatica) are more likely to become immobile
on the road when approached by automobile-related stimuli
than when left undisturbed. Although their experiment did
not completely control for disturbance, making it impossible
to separate out the effects of light and disturbance, their results
are consistent with the idea that rapid shifts in illumination
can alter the behavior of frogs at night.
Physiological consequences are also possible. For example,
Leopard Forgs, Rana pipiens kept under constant lighting suf-
fered from retinal irregularities (Bassinger and Matthes 1980)
and Common Asian Toads B. melanostictus show reduced
sperm production when maintained in constant light (Biswas
et al. 1978). e expression of genes that, in turn, regulate
other physiological processes can also be altered by constant
illumination (Baggs and Green 2003; Green and Besharse
1996; Steenhard and Besharse 2000). e number of species
that may be susceptible to these various effects and the mag-
nitude of change in illumination intensity or duration that is
necessary to elicit such responses remain unknown.
Turtles — A number of freshwater turtles survive within urban
matrices, perhaps because of their unusual resistance to various
pollutants (Gasith and Sidis 1984). Increasingly, species com-
mon in the pet trade, such as the Red-Eared Slider Trachemys
scripta elegans, are also becoming widely established in urban
settings (e.g., Lever 2003; Perry et al. 2007), presumably fol-
lowing their release or escape. Information about the ecology
of such species in urban and near-urban environments, and
on the influence of lights upon them, is lacking. e single
exception involves a laboratory study in which Chinese Soft-
Shelled Turtles (Trionyx sinensis) were shown to have lower
food uptakes and growth rates at higher light intensities (Zhou
et al. 1998). It is quite possible that species such as softshell
turtles (Trionychidae) that sleep on shore at night would also
be more exposed to predation due to increased visibility to
predators in lighted landscapes.
Lizards — Many lizard species exist in urban peripheries.
Nonetheless, we have not been able to find any studies show-
ing effects of lights on these reptiles. Further study on the
impacts of night lighting in these habitats is needed.
Snakes — Some aquatic snakes track the lunar cycle in their
activity and foraging patterns (Andreadis 1997; Houston
249
effects o f a rtificial l i g h t s o n h e r P s
and Shine 1994; Madsen and Osterkamp 1982). e issue
of artificial lights disrupting the lunar cycle in natural areas
(i.e. biodiversity reserves) adjacent to urban areas is of con-
cern, but studies exploring this potential problem are absent.
Increased lighting may affect snake foraging success. Predation
success rates for some species that prey on snakes increase with
increased illumination (Bouskila 1995), and some snake prey
reduce their foraging activity in response to increased illumi-
nation (e.g., Bouskila 1995; Bowers 1988).
ur b a n b eaches and e sTuaries
Many of the world’s largest cities originated as port towns.
Other urban centers have more recently emerged around tour-
ist destinations, and often feature heavily-developed beaches.
In many cases, the same sandy beaches treasured by vacationers
are also the traditional sites for sea turtle nesting. Sea turtles at
such locations probably offer the best case studies of the effects
of artificial lighting on any taxonomic group (e.g., Withering-
ton 1992b). Other species, such as the diurnal Fringe-Toed
Lizard (Acanthodactylus scutellatus) and the nocturnal Leaf-
Nosed Snake (Lytorhynchus diadema) also inhabit those same
dunes (e.g., Perry and Dmi’el 1995) and may be exposed to
ambient light from nearby cities.
Frogs — Although no species of frog tolerates the high salin-
ity associated with marine beaches per se, some (e.g., Marine
Toads Bufo marinus, Crab-Eating Frogs Rana cancrivora) are
known to breed in brackish water. One of them, B. marinus,
has been widely introduced around the world (Lever 2003)
and is commonly found near urban centers. In Hawaii,
Guam, and elsewhere, large numbers will forage under lights,
clearly taking advantage of the increased prey abundance (J.
Lazell pers. comm.; G. Perry unpubl. data). However, the
consequences of lights for amphibian populations inhabiting
beaches and estuaries remain unstudied.
Turtles — McFarlane (1963) described how hatchling turtles
in Florida, after emerging from their nests, were attracted
to street lighting visible at the beach. Many crawled inland,
crossed a coastal roadway en route to the lights, and were
crushed on the road by passing cars. We now know that
hatchlings worldwide are commonly attracted to light x-
tures (Philibosian 1976; Peters and Verhoeven 1994), and
that most turtles attracted to lights die from exhaustion, dehy-
dration, and predation. Other sources of illumination (such
as abandoned campres on land) can also be deadly (Mor-
timer 1979). Articial lighting also affects adult turtles by
degrading the quality of their rookery sites. Nesting attempts
(crawls of gravid females up the beach to nest) each night
by Green Sea-Turtles (Chelonia mydas) and Loggerheads
(Caretta caretta) were reduced to almost zero at historically
important sites (Melbourne Beach, Florida; Tortuguero,
Costa Rica) when these locations were experimentally
exposed to lighting (Witherington 1992b). When the lights
were turned off, nesting attempts each evening immediately
increased. In Florida, the spatial pattern of articial lighting
probably accounts for the present distribution of the “pre-
ferred” rookery sites along the East Coast (approximately
75,000 loggerhead nests annually). About 90% of all nests
are deposited at ve beach sites characterized primarily by
their lower exposure to articial lighting (Salmon 2003).
The same sites are also preferentially used by Leatherbacks
(Dermochelys coriacea), C. mydas, and C. caretta, which
elsewhere tend to nest at different locations. This suggests
that the negative effects of coastal development and its asso-
ciated lighting, rather than features that have traditionally
promoted female reproductive success and hatchling sur-
vival, currently determine where marine turtles nest.
Lizards — Some species of lizards inhabit beaches, and a few,
such as Black Iguanas (Ctenosaura similis), may occasionally be
seen near human habitation. Slightly further from the beach
proper, species such as the Fringe-Toed Lizards Acanthodacty-
lus scutellatus and A. schreiberi inhabit dune formations nestled
within seaside urban communities (Perry and Dmi’el 1995).
However, such cases are uncommon, and we are unaware of
any studies examining the influence of lights on such species.
Snakes — A number of snake species in the family Elapi-
dae (some authors place them in the families Hydrophiidae
and Laticaudidae) spend their lives in the sea and most can
at times be found near land, if only briefly. Some of these
(e.g. Laticauda species) can be quite common along beach-
retaining walls in urban south-Pacific cities that are exposed to
lights. Another group of snakes, the Homolopsines, primar-
ily occur in mudflats and forage at night. Finally, terrestrial
species such as the Sand Snake (Psammophis schokari) and
Lytorhynchus diadema inhabit dune formations nestled within
sea-side urban communities in Israel (Perry and Dmi’el 1995).
However, we are unaware of studies examining the effects of
lights on such species.
remediaTion
All of the work conducted to date on light pollution reme-
diation for herpetofauna involves sea turtles. Recent tests on
hatchling orientation, conducted in an arena setting, indicated
that natural cues and artificial lights “compete.” is work
offers hope of identifying a technological fix because it shows
that a reduction in the perceived “attractiveness” of artificial
lighting makes it more likely that hatchling orientation will be
based upon natural cues (Tuxbury and Salmon 2005).
A number of studies have examined the feasibility of using
alternative lighting methods that would reduce or eliminate
the negative influence on sea turtles but that would also be
acceptable to humans. Turtle-friendly lights generally emit
wavelengths between 540 and 700 nm (amber to red) and
can be produced either by designing lights that emit only the
longer wavelengths (Fig. 2) or by using filters that exclude the
250
Pe r r y e t a l .
shorter wavelengths of “broad-spectrum” lights. Salmon and
his colleagues (Halager et al. in press) developed a bioassay
that can be used to evaluate the efficacy of “turtle-friendly”
lights by giving hatchlings choices between darkness and a
light (single light experiments), or pairs of different lights.
Using this bioassay, Halager et al. (in press) found that some
lights are more attractive to turtles than others and that the
strength of attraction declines as spectral energies become
more concentrated in, and shifted toward, the longer wave-
lengths (Figs. 3, 4). Field experiments demonstrate that high-
pressure sodium vapor lamps affect marine turtles, but passing
such illumination through a filter that excludes wavelengths
below 530 nm makes these lights far less attractive to hatch-
lings (Sella et al. 2006). In fact, when this filtered lighting
is visible at nesting beaches, it no longer reduced nesting by
adults (Pennell 2000).
e use of spectrally-modified outside lighting should
increase the number of hatchlings that successfully locate
the ocean, even at urban nesting beaches. Recently, lighting
along a coastal roadway in the city of Boca Raton, Florida, was
extensively modified. Streetlights placed on posts were turned
off during sea turtle nesting season and replaced with light-
emitting diodes installed in the pavement. ese provided suf-
ficient illumination for traffic safety, but none of the lighting
was visible at the nesting beach. Behavioral tests at the beach
demonstrated that the seaward orientation of hatchling Log-
gerheads was normal when the embedded lights were on, but
disrupted when the elevated streetlights were on (Bertolotti
and Salmon 2005). It remains to be seen to what extent use of
similar technologies could help other taxonomic groups.
discussion
Artificial light, long considered a problem for astronomers
but of little concern to biologists, is increasingly viewed as a
threat by conservation biologists. A recent volume (Rich and
Longcore 2006) illustrated the pervasiveness of the problem of
artificial lights, which affect a broad range of taxa. In this chap-
ter, we focused on updating and summarizing the information
for amphibians and reptiles, but emphasize that the problems
associated with artificial night lighting likely do not stop with a
particular group of organisms. It may impact entire communi-
ties, and we find it encouraging that solutions to this problem
may also simultaneously benefit a broad range of taxa.
ere are doubtlessly additional species and populations
which use artificial lights and are not listed in Tables 1 and 2.
For example, Outen (2002) and Spellerberg (2002), identified
lights associated with roads as a potential source of concern, but
could find few studies directly evaluating this potentially wide-
spread risk (but see Mazerolle 2004; Mazerolle et al. 2005).
e reports collected by Rich and Longcore (2006) also stress
the magnitude of the lack of information on effects of artificial
night lighting for many taxonomic groups, including amphib-
ians and reptiles (Buchanan 2006; Perry and Fisher 2006;
Salmon 2006; Wise and Buchanan 2006). However, there is
reason to be concerned about the effects of artificial light on
amphibians and reptiles in general: many species are nocturnal
and many populations are in serious decline (e.g., Alford and
Richards 1999; Gibbons et al. 2000). Unfortunately, the litera-
ture demonstrates a lack of information for caecilians, tuataras,
and crocodilians, which are primarily nocturnal and could
therefore be at risk from changes in light levels.
Urban ecology is a rapidly growing discipline, but her-
petological research in urban environments remains nota-
bly underrepresented. Studies typically focus on relatively
undisturbed habitats, and even herpetofaunal surveys rarely
Fig. 2. Spectral energy distributions for four “turtle-friendly”
lights (Magnaray, M; ltered High Pressure Sodium vapor,
HPS; Twistee, T; and Beeman Red, BR). One short-wave-
length light (Beeman Blue, BB) was used as a control. Fil-
tered HPS lights are used on coastal roadway poled street-
lights in Florida; the Twistee and Beeman red are lights
designed for buildings (residential or commercial) that are
visible at marine turtle nesting beaches.
Fig. 3. Choices of hatchling sea turtles (Loggerheads, Caret-
ta caretta) presented with various lights. A no-light control
was used in each case. Differences among light sources in
relative intensities were eliminated through the use of neu-
tral density lters, so that responses shown by the turtles
were based upon spectral differences alone. Results show
that the turtles are statistically signicantly attracted to the
Twistee (T, n = 25 turtles), Beeman Blue (BB, n = 25), and
Magnaray (M, n = 35) lights, but not to the Beeman Red
(BR, n = 45) or Filtered HPS (HPS, N = 46).
251
effects o f a rtificial l i g h t s o n h e r P s
explicitly address taxa found in or near human habitation. e
biology of edificarian taxa is even more rarely reported (but
see Powell and Henderson 2008). We hope that the increased
interest in urban ecology will lead to more studies addressing
light pollution and their effects on amphibians and reptiles.
Although these influences are only beginning to be studied, a
few general patterns appear to be emerging:
1) Species vary in their sensitivity to light pollution, which
may have no effect, benefit, or negatively affect a particu-
lar taxon. us, it is important to consider the photobiol-
ogy of all taxa found in a particular habitat. For example,
sea turtle nesting problems may be reduced by shifting
the spectra of lights to longer wavelengths. Shifting spec-
tra to longer wavelengths can, however, disrupt migra-
tion in newts (which do not, fortunately, share the same
habitat). us, there may not always be simple solutions
to lighting problems other than the removal, reduction of
use, or shielding of artificial night lighting.
2) Different aspects of a given species’ biology can be affected
differently by different lighting conditions at different life
history stages.
3) ere is a paucity of research available on the negative
effects of lighting on herpetofauna. Negative effects of
light pollution, such as the disruption of orientation
in hatchling sea turtles (e.g., Witherington and Martin
1996) are well documented, but detailed studies for other
taxa are not yet available.
4) ere is a dearth of studies of the positive effects of light-
ing on herpetofauna. Positive influences, such as increased
prey availability and thermoregulatory opportunities
around artificial night lighting are better documented,
if only anecdotally, in lizards (Tables 1, 2). We are not
aware of studies that have elucidated population-level
consequences, what mechanisms are involved, and which
species are most likely to be affected.
5) Indirect effects are likely to be common. Benefits to one
species may negatively influence another, as demon-
strated by Case et al. (1994). However, studies of this
phenomenon that do not involve invasive species are only
now starting to reach the literature (Rich and Longcore
2006).
6) e ability of artificial light to enhance the invasive poten-
tial of some species should be a source of broad concern.
Some of the species listed in Table 1 and many of those in
Table 2 were observed in areas outside their native range.
e ability to use human habitats, which are often char-
acterized by having additional lighting during the night,
can be beneficial to invasive species, many of which first
colonize urbanized areas. For species that are not only
tolerant of such conditions but can also take advantage of
the night-light niche, establishment of viable populations
may be easier. Almost no information is available on the
impacts of invaders such as geckos, which are generally
perceived as innocuous, yet it seems likely that at least
some native species (particularly invertebrate prey) must
be negatively affected. Light-aided invasive species may
also spread disease and exotic parasites to native species.
Is it possible to resolve such conflicts of interest between
urban residents and urban amphibians and reptiles? New tech-
nology, briefly reviewed above, offers some promising options
for providing illumination that satisfies human requirements
while minimizing effects on other species. However, solving
the light pollution problem necessitates light management,
including protocols that eliminate the influence of artificial
lighting on wildlife by, for example, turning off unnecessary
lights, reducing wattage, shielding and lowering luminaires, or
creating natural light barriers, such as dune or wooded areas,
between light sources and wildlife habitats (Witherington
and Martin 1996). However, humans often perceive lighted
environments as more pleasing or safe. For example, lighting
along roadways and in city parks is often considered neces-
sary for pedestrian and vehicular safety. us, there may be
resistance to reducing the amount of lighting at urban sites.
ere is much room for research on the human dimensions
of the problem and such work can hopefully help identify
technological solutions that benefit wildlife and are broadly
acceptable to the public. We hope that such solutions can be
incorporated rapidly not just where a particular species of sea
turtle or gecko is found, but on a global scale commensurate
with the scope of the artificial light problem.
managemenT r ecommendaTions
e information presented in this chapter clearly indicates
the potential for multiple types of effects on amphibians
and reptiles resulting from artificial night lighting. Although
Fig. 4. Choices of hatchling sea turtles (Loggerheads, Caret-
ta caretta) in tests in which paired light presentations were
made. Turtles are signicantly attracted to the Twistee (T)
and Magnaray (M) lights when each is matched with a l-
tered HPS light (n = 29 and 60, respectively, for each test).
However, turtles are signicantly attracted to the ltered
HPS light when it is paired with a Beeman Red light (BR,
n = 40), which is also less attractive to the turtles than the
Beeman Blue light (BB, n = 25).
252
Pe r r y e t a l .
the most extensive work has been carried out on sea turtles
at urban beaches, preliminary evidence indicates that many
species are likely at risk. Although it is clear that much more
research is needed in this area before firm conclusions can be
drawn, work reviewed above has begun identifying potential
problems and solutions to these problems, which we are hope-
ful can effectively be incorporated into standard practices. We
recommend that managers adopt a precautionary approach
and attempt to minimize consequences without waiting for
researchers to confirm the impacts on a particular species or
habitat. It is clear that the best approach for the conservation
of native taxa involved is returning habitats as closely as pos-
sible to their natural lighting conditions, primarily through
the removal of unnecessary lighting and shielding of neces-
sary lighting. It is worth noting that several entities that have
experimented with reducing lighting have also recouped their
investment in reduced power costs (e.g., International Dark
Sky Association: http://www.darksky.org/infoshts/pdf/is191.
pdf; accessed May 2006).
summary
Amphibians and reptiles have not evolved with artificial
lighting at night. us, alteration of the natural variation in
diurnal and nocturnal light intensities and spectral properties
of lights has the potential to disrupt their physiology, behav-
ior, and ecology. Our review identified possible effects of night
lighting on many species of amphibians and reptiles. However,
it also reveals that conclusive data are often lacking. Few stud-
ies on the consequences of artificial lights for amphibians and
reptiles have been conducted to date, and in many that might
be relevant, researchers have not recorded the illumination
or irradiance at which experiments are conducted. us, it is
currently impossible to precisely gauge the effects of artificial
night lighting on taxa found in urban, light-polluted environ-
ments. e one exception is the information available on the
negative impacts of artificial lights on hatchling sea turtles,
which has received considerable coverage in both scientific and
popular media. With that exception, we believe it is too early
to draw sweeping conclusions and to provide broad manage-
ment recommendations, beyond pointing out the urgent need
for more information. However, we identify light pollution as
a serious threat that should be considered as part of planning
and management decisions in the maintenance or conserva-
tion of urban areas containing amphibians and reptiles.
Acknowledgments — We thank C. Rich and T. Longcore
for first getting all of us together, and the many colleagues
who have helped us locate obscure publications or graciously
allowed us to use unpublished observations in this work. is
is manuscript T-9-1047 of the College of Agricultural Sciences
and Natural Resources, Texas Tech University.
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