Natural History Notes
28 Herpetological Bulletin  - Number 92
ANILIUS SCYTALE (Red pipesnake):
REPRODUCTION. The Red pipesnake inhabits
northern South America from southern and eastern
Venezuela, Guyana, Suriname, and French Guiana
through the Amazon Basin of Colombia, Ecuador,
Peru, Bolivia, and Brazil (McDiarmid et al., 1999;
Uetz, 1995–2005). It is a viviparous snake with
fossorial habits that feeds mainly on elongate
fossorial and aquatic vertebrates (Martins &
Oliveira 1999), and which escapes from predators
either by fleeing (flight category, Seigel & Fitch,
1984) or by using some form of active defense
(stand-and-fight; Seigel & Fitch, 1984).
Life history data on Ecuadorian populations of
this species are scarce or unpublished. The only
reproductive data available for Anilius in Ecuador
is that reported by Duellman (1978), who states:
‘one female collected in June with small ovarian
eggs’. Cunha & Nascimento (1981) reported on
seven females from Brasil (520–945 mm total
length [TTL]) collected between March and
November with ovarian eggs (3–37 eggs/female),
two females collected in March and July with
eight and ten developing embryos each one; and,
seven other females (530–841 mm TTL) collected
between February and July with developed
embryos (5–8 embryos/female, 184–218 mm
TTL). Among these, one female (841 mm TTL)
had twelve embryos with a mean TTL of 203.9 ±
2.1 SE mm (194–214 mm TTL, mode = 210 mm),
and another (680 mm TTL) had nine embryos with
a mean TTL of 196.0 ±2.3 SE mm (185–205 mm
TTL, mode = 201 mm). Cunha & Nascimento
(1981) stated that A. scytale appeared not to have
a defined breeding season, independent from the
rainy or dry season, and suggested a gestation
period of four to six months. In the Iquitos region
(Peru), Dixon & Soini (1986) reported on one
female (1184 mm TTL) that gave birth to six
young in February 1972; a smaller female that
gave birth to four young in January 1966; and a
very young specimen taken in early March.
Martins & Oliveira (1999) reported on one female
(598 mm snout-vent length [SVL], 24 mm tail
length [TL]) that gave birth to eight young
(154–163 mm TTL) in October; another (898 mm
SVL, 29 mm TL, 181 g) that gave birth to 15
young (206–234 mm TTL; combined mass of all
15 young = 52 g; relative clutch mass [RCM] =
total offspring mass/female total mass = 0.29); a
female (424 mm SVL, 17 mm TL) with seven
fully developed embryos (157 – 173 mm TTL) in
October; and, a female (898 mm SVL, 29 mm TL)
with five developing embryos.
On 26th January 1999, a female A. scytale was
collected in the Centro Mashient, province of
Morona-Santiago, Ecuador. The specimen (FHGO
2355) was maintained in captivity and gave birth
to 18 living and 8 stillborn young on 6th February
1999 (FHGO 2356-64, 2373-74, 2378, 2380,
2387-88, 2390-91, 2393-95, 2397, 2403, 2440).
The female had a TTL of 1027 mm, and a mass of
155.7 g when collected. The 18 young had a mean
TTL of 213.7 ± 2.5 SE mm (190–230 mm TTL,
mode 218 mm), and mean mass of 2.8 ± 0.1 SE
mm (2.2–3.3 g, mode=2.8 g). Four of the stillborn
snakes had a mean TTL of 212.5 ± 3.1 SE mm
(206–221 mm TTL) and mean mass of 2.7 ± 0.1
SE mm (2.4–2.9 g). Total litter mass was c. 70 g,
RCM = 0.45. The 18 young snakes remained alive
for between 53 to 69 days and died of unknown
Additional data presented herein indicate that A.
scytale litter size varies from 4 to 18 young, with
an SVL range of 154–234 mm). Reproductive
females had a mean SVL of 718.5 ± 54.2 SE mm
(424–1142 mm, n = 15), and relative clutch mass
values range from 0.29–0.45. Notwithstanding the
small sample size, RCM and SVL range in this
species appears to be relatively high compared
with other viviparous snakes (e.g. Seigel & Fitch,
1984; Seigel et al., 1986). Also, although a
decrease in RCM is often associated with
increasing body size in viviparous snakes (Seigel
et al., 1986), A. scytale shows a different trend.
However, this could be explained by the species’
fossorial habits, supporting Iverson’s hypothesis
(in Seigel et al., 1986) regarding the secretiveness
of fossorial species permitting higher RCM.
Species with burrowing habits are generally less
Natural History Notes
Number 92 - Herpetological Bulletin  29
exposed to visual predators and the reproductive
cost to females is thus likely to be relatively minor
in comparison with species that occur primarily
above ground, supporting Seigel et al.’s
hypothesis (1986) regarding the ecological
explanations for RCM and SVL relationships.
Ovarian eggs, developing embryos and young
have been reported from January to July, and in
October and November, suggesting continual
reproduction (Seigel & Ford, 1987) and
supporting Martins & Oliveira’s hypothesis
I am grateful to Jean-Marc Touzet and Ana María
Velasco for granting access to the specimens
deposited at the FHGO, to Dwain Holmes for
donating the pregnant specimen of Anilius scytale.
To Anita Peñaherrera, Gabriel Touzet, Margarita
Brandt, Andrés León, and Tomi Sugahara for
laboratory assistance. To Roy McDiarmid and to
the Savanna River Ecology Laboratory for sharing
literature. My gratitude to Maria Elena Heredia
and Laura Heredia for financial and moral support.
Universidad San Francisco de Quito provided
Cunha, O. R. da, & Nascimento, F. P. do. (1981).
Ofídios da Amazönia: XIII – Observacões sobre
a viviparidade em ofídios do Pará e Maranhão
(Ophidia: Anilidae, Boidae, Colubridae e
Viperidae). Bol. Mus. Para. Emílio Goeldi 109,
Dixon, J. R. & Soini, P. (1986). The Reptiles of the
Upper Amazon Basin, Iquitos Region, Peru.
Milwaukee: Milwaukee Pub. Mus. Press. 154
Duellman, W. E. (1978). The biology of an
equatorial Herpetofauna in Amazonian Ecuador.
Univ. Kansas Mus. Nat. Hist. Misc. Publ.,
Kansas 65, 1-352.
Martins, M. & Oliveira, M. E. (1999). Natural
history of the snakes in forests of the Manaus
region, Central Amazonia, Brazil. Herpetological
Nat. Hist. 6 (2), 78-150.
McDiarmid, R. W. Campbell, J. A. & Touré, T.
(1999). Snake species of the World: A taxonomic
and geographic reference. Vol.1. Washington,
D.C.: The Herpetologist’s League. 511 pp.
Seigel, R. A. & Fitch, H. S. (1984). Ecological
patterns of relative clutch mass in snakes.
Oecologia 61, 293-301.
Seigel, R.A. & Ford, N.B. (1987). Reproductive
ecology. In Snakes: Ecology and Evolutionary
Biology, pp. 210-252. Siegel, R.A. Collins, J.T.
& Novak, S.S. (Eds.). New York: Macmillan
Seigel, R. A. Fitch, H. S. & Ford, N. B. (1986).
Variation in relative clutch mass in snakes
among and within species. Herpetologica 42(2),
Uetz, P. (1995-2005). The EMBL Reptile
Database. Online. EMBL Heidelberg:
on December 2004].
DIEGO F. CISNEROS-HEREDIA
College of Biological and Environmental
Sciences, Universidad San Francisco de Quito,
Ave. Interoceánica y calle Diego de Robles,
Campus Cumbayá, Edif. Maxwell. Casilla Postal
17-12-841, Quito, Ecuador. E-mail: