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264 IGUANA  •  VOLUME 14, NUMBER 4  •  DECEMBER 2007 NATURAL HISTORY RESEARCH REPORTS

Escape Behavior in 
Cuban Curly-tailed Lizards

Several aspects of escape behavior are pre-
dictable by escape theory based on
expected costs due to predation risk and
escaping. Although the function of pur-
suit-deterrent signaling is to dissuade
predators from attack, relatively little is
known about relationships between spe-
cific components of escape and the sig-
naling behavior. COOPER (2007.
Herpetologica 63: 144–150) studied
effects of the risk factor distance from
refuge on flight initiation distance, dis-
tance fled, probability of entering refuge,
and the distance between predator (an
approaching human) and prey when
pursuit-deterrent display begins (display
distance) in the Cuban Curly-tailed
Lizard (Leiocephalus carinatus). The
author also investigated whether starting
distance (distance between predator and
prey when approach begins) affects
escape behaviors. As predicted by escape
theory, flight initiation distance and dis-
tance fled were greater and refuge entry
was less probable at greater distance from
refuge, indicating that qualitative predic-
tions of escape theory apply to pursuit-
deterrent signalers. Starting distance did
not affect escape behaviors, presumably
because it did not affect perceived risk,
but might do so at a faster approach
speed. Display distance and flight initia-
tion distance were identical in the data
set analyzed, but individuals sometimes
perform tail displays prior to fleeing.

Native Predators May Limit 
Iguanas in Florida

Known predators of Green Iguanas
(Iguana iguana) in Florida include
Raccoons (Procyon lotor), domestic dogs
(Canis familiaris), Yellow-crowned Night
Herons (Nyctanassa violacea), Florida
Burrowing Owls (Athene cunicularia
floridana), and a hawk (Buteo sp.). Smith
et al. (2007. Journal of Kansas
Herpetology 23: 7–8) report nest preda-
tion and attempted adult predation on
Green Iguanas by a Gray Fox (Urocyon
cinereoargenteus) and suggest that avian
and mammalian predators may poten-
tially function as limiting factors on col-
onization patterns of exotic iguanas in
Florida.

Survival of Timber Rattlesnakes
(Crotalus horridus)

Juvenile survival is one of the least
known elements of the life history of
many species, in particular snakes.
BROWN ET AL. (2007. Copeia 2007:
656–671) conducted a mark-recapture
study of Timber Rattlesnakes (Crotalus
horridus) from 1978–2002 in northeast-
ern New York near the northern limits
of the species’ range. They marked 588
neonates and estimated annual age-, sex-,
and morph-specific recapture and sur-
vival rates. Wild-caught neonates (field-
born, n = 407) and neonates produced
by captive-held gravid females (lab-born,
n = 181) allowed comparison of the
birthplace, or lab treatment effect, in
estimated survival. Recapture rates
declined from about 10–20% over time
while increasing from young to older age
classes. Estimated survival rates (S ± 1
SE) in the first year were significantly
higher among field-born (black morph:
S = 0.773 ± 0.203; yellow morph: S =
0.531 ± 0.104) than among lab-born
snakes (black morph: S = 0.411 ± 0.131;
yellow morph: S = 0.301 ± 0.081).
Lower birth weights combined with a
lack of field exposure until release appar-
ently contributed to the lower survival
rate of lab-born snakes. Subsequent sur-

vival estimates for 2–4-yr-old snakes
were S = 0.845 ± 0.084 for the black
morph and S = 0.999 (SE not available)
for the yellow morph, and for > 5-yr-old
snakes S = 0.958 ± 0.039 (black morph)
and S = 0.822 ± 0.034 (yellow morph).
The most parsimonious model overall

Tail-curling may serve as a pursuit-deterrent signal in Cuban Curly-tailed Lizards (Leiocephalus
carinatus). 

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A Gray Fox (Urocyon cinereoargenteus) exca-
vating a Green Iguana (Iguana iguana) nest
and eating the eggs at Hugh Taylor Birch
State Park in Broward County, Florida.

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N A T U R A L  H I S T O R Y  R E S E A R C H  R E P O R T S

For young Timber Rattlesnakes (Crotalus
horridus) (ages 1 yr and 2–4 yr), survival
tended to decline over the years for both
“yellow” and “black” morphs, whereas for
adult snakes (> 5 yr), survival was constant
or even increased slightly.

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IGUANA  •  VOLUME 14, NUMBER 4  •  DECEMBER 2007 265NATURAL HISTORY RESEARCH REPORTS

contained an independent time trend for
survival of each age, morph, and lab-
treatment group. For snakes of the first
two age groups (ages 1 yr and 2–4 yr),
survival tended to decline over the years
for both morphs, whereas for adult
snakes (> 5 yr), survival was constant or
even increased slightly. These data on
survival and recapture are among the
first rigorous estimates of these parame-
ters in a rattlesnake and among the few
available for any viperid snake. These
data are useful for analyses of the life-
history strategy, population dynamics,
and conservation of this long-lived
snake.

Ringneck Snakes are Toxic to Prey
Ringneck Snakes (Diadophis punctatus)
are suspected of being venomous
because their Duvernoy’s gland secre-
tions have high levels of phospholipase
activity, which is characteristic of many
viperid and elapid venoms, and because
anecdotal reports of feeding behavior are
consistent with the use of a venom.
O’Donnell et al. (2007. Toxicon 50:
810–815) tested the toxicity of

Northwestern Ringneck Snake (D. p.
occidentalis) oral secretions to a natural
prey species, Northwestern Garter
Snakes (Thamnophis ordinoides), by
injecting 2–35 µl of oral secretions
intraperitoneally. All doses were 100%
lethal within 180 min. The dose signifi-
cantly affected the time to loss of a right-

ing response. Neither injection of saline
nor denatured oral secretions resulted in
loss of a righting response or any visible
detrimental effects. The authors sug-
gested that Northwestern Ringneck
Snakes may have evolved venom to sub-
due larger prey items than the snake
would otherwise be capable of taking.

Virginia Herpetological Society
Publications On-line

The Virginia Herpetological Society has
digitized all of its publications from 1958
to 2005, providing easy access to almost
50 years worth of field notes, articles, 
and the history of the society. Interested
herpetologists are encouraged to access
this resource at fwie.fw.vt.edu/
VHS/ (or publications specifically at
fwie.fw.vt.edu/VHS/vhs_history.htm).

Fourth Annual Sonoran Desert
Herpetological Symposium

The Tucson Herpetological Society and
its cosponsors are pleased to announce
the fourth symposium on “Current
Research on Herpetofauna of the
Sonoran Desert” from 11–13 April
2008. The goals of this meeting are: (1)
Presenting research on the herpetofauna
of the Sonoran Desert (in the states of
Arizona, Sonora, and on the Baja
California Peninsula and gulf islands),

and (2) Bringing the interested commu-
nity together to get better acquainted.
Invited speakers are Harry Greene, Ed
Moll, and Cecil Schwalbe.

The first three Sonoran Desert

Herpetofaunal symposia were an
epiphany for many. These symposia
revealed the wide variety of research being
conducted in the area. For more informa-
tion, see: http://tucsonherpsociety.org/.

N E W S B R I E F S

Northwestern Ringneck Snake (Diadophis punctatus occidentalis) oral secretions are toxic to a
natural prey species, Northwestern Garter Snakes (Thamnophis ordinoides). 

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The Tucson Herpetological Society and cosponsors announce the fourth symposium on
“Current Research on Herpetofauna of the Sonoran Desert.” 

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