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CAPTIVE BREEDING AND CONSERVATION
REPRODUCTION CYCLE OF THE EASTERN EGG-EATER SNAKE
Dasypeltis medici medici (BIANCONI, 1859) IN CAPTIVITY
Alessandro Paterna1
Submitted March 13, 2016
For the first time the data on the complete reproductive cycle of the eastern egg-eater snake (Dasypeltis medici
medici) have been documented and recorded. The data, collected from specimens in captivity, illustrate the age
when they reach sexual maturity, mating and its frequency in the course of the year, gestation, clutch size, egg
morphology, incubation times as well as different results based on the parameters used, appearance and general
characteristics of the hatchlings.
Keywords: Serpentes; Colubridae; Dasypeltis medici medici; eastern egg-eater snake; mating; gestation; egg-lay-
ing; hatchlings.
INTRODUCTION
The species Dasypeltis medici medici, originally de-
scribed as Dipsas medici by Bianconi in 1859, was later
split into two subspecies by Gans (1957): Dasypeltis
medici lamuensis and the nominal one (Fig. 1). The east-
ern egg-eater snake, as its name suggests, inhabits a geo-
graphical range comprising southern Kenya, Tanzania,
northern South Africa, and has a specialized diet on bird
eggs. In contrast to most other colubrids, this species
does not feed on whole eggs but only on their content.
A specialized sequence of vertebrae in the neck re-
gion with sharp tips protruding into the esophagus, al-
lows the snake to break the eggshell when it passes along
the throat (Gans, 1952; Gartner and Greene, 2008). These
“saw-toothed” vertebrae, combined with contractions of
muscles of the neck, create cracks on the egg’s surface.
The snake then breaks and compresses the egg, drinks its
contents and vomits the emptied eggshell. This feeding
process is supported by a very elastic skin of the jaws and
the neck region, which allows the snake to ingest eggs of
dimensions which are larger than its head (Gans, 1954).
Another peculiar characteristic of this species is its
resemblance in appearance and behavior to some African
viperids. Its pattern, especially in the head portion, looks
like the one of the rhombic night adder (Causus rhom-
beatus ). Additionally it has small serrated scale rows
along the sides. When the snake feels threatened, these
are used by disposing its body in an “S” shape and rub-
bing the modified scales against each other, “imitating”
the appearance and the sound of the saw-scaled viper
1026-2296/2017/2403-0228 © 2017 Folium Publishing Company
Russian Journal of Herpetology Vol. 24, No. 3, 2017, pp. 228 – 234
1via F. Brandimarte, 3 - 64100 Teramo (TE) Italy;
e-mail: alessandro.paterna@hotmail.com
Fig. 1. Portrait of Dasypeltis medici medici.
(Echis pyramidum, former: E. carinatus ) (Gans and
Richmond, 1957; Mehrtens, 1987).
The genus Dasypeltis, the species’ varieties and the
populations belonging to it have been object of interest
and revisions on different occasions (Gans and Lover-
idge, 1952; Gans, 1959; Trape et al., 2012).
Nevertheless, many aspects regarding the species’
behavior, their habits, and their characteristics in general
are still not quite known, especially those of D. medici
medici (Branch, 1988b; Loveridge, 1942; Marais, 1992,
2004; McLachlan, 1979).
This study is about this species’ reproductive cycle,
based on observations and materials collected from spec-
imens kept under human care.
MATERIAL AND METHODS
A study about the captive breeding of several speci-
mens of D. medici medici originating from Usambara
Mountains (Tanzania), started from the beginning of
2013.
The initial group, a trio of sub-adults, consists of one
male and two females of the same dimensions. Due to ap-
propriate housing of the animals, they never showed
signs of stress or unease. On the contrary, in a short time
the snakes not only reached sexual maturity, but even
bred several times. Additionally, the hatchlings that de-
rived from the original group grew healthily to sexual
maturity, copulated, and produced a second generation.
Adult specimens were housed in terrariums with the
base measuring 40 × 70 cm, and an height of 40 cm,
while smaller structures were dedicated to hatchlings and
young ones. Temperature and humidity parameters were
modified during the year period to imitate the alternating
of the dry and rainy seasons which characterize the re-
gion these animals are originating from. Terrariums’ in-
ternal temperatures never dropped under 16°C and raised
over 30°C. Humidity level was kept low during the dry
periods and raised (moistening regularly) both during the
rainy seasons and the shedding times. In order to help the
snakes to acclimate, the structures were provided with
hot spots and constant humid areas.
During the whole period of the study all the details of
their biology have been noted. Data regarding behavior,
feeding, growth, sexual maturity, copulation, gestation,
egg-laying, incubation and hatching have been recorded
and documented with photographic material. Mass of
snakes and eggs have been measured with an electronic
balance. Stated lengths of the specimens refer to their
total lengths (TL to the nearest ±0.5 cm). Determination
of sexes was carried out by eversion of the hemipenes.
The eggs were incubated using a specific incubator or
kept at room temperature, employing vermiculite, sphag-
num or peat as a substrate to keep the right humidity
level. Temperatures refer to degrees centigrade.
RESULTS
Sexual maturity. In both sexes, sexual maturity in
the eastern egg-eater snake occurs when the snake
reaches adult size. For successfully mating and breeding,
these snakes must be at least about 50 cm long. In my
study they have a minimum recorded weight of 34 g for
females, and 25 g for males. A male that had hatched
from the second generation, copulated with an unrelated
adult female when it was 15 months old (452 days from
hatching). This copula resulted in the deposition of 4 fer-
tile eggs and healthy hatchlings.
This species gains weight as well as length very
quickly. The recorded maximum size belongs to a female
with a length of 60 cm and a weight of 55 g when she was
not gravid.
Copula and gestation. Based on my observations,
copulation always takes place on the same day of female
shedding or at the most, the day after (Fig. 2e). Also cop-
ulations that had been observed on the same day, or the
day after a female had laid eggs resulted in fertile
clutches. In a specific case, egg-laying and consequen-
tially mating, occurred within 24 h following the pre-de-
position shed of one of the females (Fig. 2g).
Copulation can take place either on the ground or on
branches (Fig. 2f,h), in bushes or in the inside of the pro-
vided hiding places. The bodies of the two specimens are
usually oriented in opposite directions, with only the re-
spective cloaca in contact. Exceptions occur if mating
takes place in a smaller area. Only in a single occasion I
observed a male holding a female with its jaws, biting it
at about the first third of its length, with the last half of
the bodies in parallel contact on the sides.
Mating usually lasts several hours, and despite the
fact that D. medici medici is essentially a nocturnal spe-
cies, copula can occur either at daytime or during the
night. The longest one recorded had duration of 11 h,
with a consequential loss of body weight of the male, rep-
resenting 1/7 of its body mass (weighing 35 g before and
30 g after the copula). The same male, sharing the same
terrarium with two females, has been observed mating 6
times in 9 months (from April 2013 to January 2014, with
a pause period lasting from October to December)
(Table 1).
One of the two females of the original trio laid 6 eggs
(3 of which were infertile) without any observable mat-
ing in the previous 10 months (Fig. 3d). On the other
hand, the other female, which was separated from the
Reproduction Cycle of the Eastern Egg-Eater Snake Dasypeltis medici medici in Captivity 229
230 Alessandro Paterna
Fig. 2. a, Specimens just hatched from the clutch pictured in Fig. 3a;b, dimensions of a hatchling and a three months old specimen; c, portrait of a
six months old specimen; d, one year old specimen; e, adult female shedding; f, mating occurring on the ground; g, mating occurring in the deposi-
tion box right after egg laying; h, mating occurring on branches.
male after mating, did not lay additional clutches except
the one originating from the last copula.
The gestation period can be very variable. From the
data collected from three females I can say that the time
between copula and deposition of the eggs varied from
shorter periods of 56 – 79 days, to longer ones of 126 –
142 days (reached by a single female) (Table 2).
At the end of gestation the presence of the eggs in the
females becomes very evident, especially in the proxim-
ity of the cloaca. Females shed their skin before egg-lay-
ing, usually from 1 to 6 days previously. In the days pre-
ceding deposition, females remain in the place they chose
to lay the eggs (in all cases I observed it was the box I had
prepared for the occasion), from where they will not exit
until the deposition will be concluded. Generally the fe-
males did not leave the clutch until it was removed, and
in some cases mating occurred in the deposition box after
the eggs had been laid (Fig. 2g).
Based on my experience the clutch size can
vary from 2 to 6 eggs, with an average of 3 or 4
(Fig. 3a,c–e). Eggs are white in color with an elongate
shape. Their diameter usually measures about 1/3of
their total length, with some variations based on the fe-
male’s dimensions and the clutch size.
The smaller ones of the fertile eggs observed, mea-
sured 32 × 14 mm (Fig. 3c), bigger ones reaching dimen-
sions of up to 55 × 14 or 50 × 19 mm (Fig. 3a). The eggs
weight at the moment they are laid can vary from 4 to 8 g.
During incubation, within days, the volume and the
mass of the eggs increase, some weighing as much as
16 g before they hatch, growing 1 g per week during the
last month.
Unfertile eggs are easily identifiable. Some of them
have visibly smaller dimensions and a color which differs
from that of the fertile ones. Candling the eggs is an easy
and secure way to verify the presence of blood vessels
and capillaries in their inside (Fig. 3f,h).
Eggs’ appearance can differ from clutch to clutch.
Their surface can be exclusively and homogeneously
smooth (Fig. 3a,c,e), or entirely covered by concretion
shaped like stars or asterisks in different dimensions.
(Fig. 3b,d,f–h).
Eggs of the latter type were laid after females were
exclusively fed with common quail eggs (Coturnix cotur-
nix ) during the whole gestation period and before. This
may be a hint to a higher amount of calcium in the quail
eggs than in those of the other birds that were fed to the
snakes (Gomathi et al., 2014, Tolik et al., 2014).
Depending on the diet and the frequency of feeding, each
female can lay eggs of either variety, but according to my
experience, each clutch consists of only eggs of the same
variety. The texture of the surface of the eggs does not en-
tail any difference in the embryos or the hatchlings.
Incubation and hatchlings. Depending on incuba-
tion temperature and other factors that could not be iden-
tified yet, length of incubation can vary. Investigations
with different clutches incubated at different tempera-
Reproduction Cycle of the Eastern Egg-Eater Snake Dasypeltis medici medici in Captivity 231
TABLE 1. Data about the Complete Reproductive Cycle of Two Females and a Single Male in the Years 2013 – 2014
Year Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.
2013 }aMD H
2013 }bMMD H
2013 – 2014 }aHMMD
2014 }b* DH
2014 }aMDH
Note. M, mating; D, deposition; H, hatch; * Mating was not observed.
TABLE 2. Data of Different Clutches.
Clutches Days
of gestation No. of eggs Temperature
of incubation, °C Days of inc. Hatchling’s
weight, g Sex ratio
}a-1st 73 4 19–28 87 2–4 3x–0}
}b-1st 56 2 19–28 93 4 2x–0}
}a-2nd 126 3 27.5–28 76–77 2–3 1x–2}
}b-2nd ? 6 (3 unfertile) 24 – 26 104 – 105 4 0x–2}
}a-3rd 142 3 24 – 26 103 – 105 3 – 4 0x–3}
}c-1st 79 4 26–28 69–71 3 1x–3}
Note. Where the number of the specimens hatched is lower than the one of fertile eggs it’s due to the death of the embryo in the egg during incubation.
232 Alessandro Paterna
Fig. 3. a, Clutch consisting of two very elongate eggs with smooth surface; b, hatchling cutting the shell of an egg with star-shaped concretions; c,
clutch of four eggs with smooth surface; d, clutch of six eggs with star shaped concretions on the surface; e, clutch of four eggs with smooth sur-
face; f, candling an egg with a surface with sun shaped concretions; g, close-up view of star shaped concretions on an egg’s surface; h, egg candling
shows blood-vessels, capillaries and the embryo on the bottom.
tures have been made (Table 2). With an incubation tem-
perature range of 24 – 26°C (2 clutches/6 eggs) they
took from 103 to 105 days to hatch. Eggs incubated at
27.5 to 28°C (1 clutch/3 eggs) hatched after 76 – 77
days, while incubated at 26 to 28°C (1 clutch/4 eggs) the
days needed were from 69 to 71. A third test (2
clutches/6 eggs) was made incubating the eggs at room
temperature with a minimum of 19°C reached during
night time, and a maximum of 28°C at daytime. With this
temperature the eggs hatched within 87 to 93 days.
From my data it looks like male hatchlings are pre-
vailing (5 males, 0 females out of 2 clutches from 2 dif-
ferent females) if the eggs are incubated at temperatures
varying from 19 – 28°, whereas there are more females
(2 males, 10 females out of 4 clutches from 3 different fe-
males) among the hatchlings of the clutches that are incu-
bated at more constant temperatures with a higher mini-
mum value. In order to find out the dependency of incu-
bation temperature and sex of the emerging hatchlings in
this species, more investigation should be done in the
future.
When candling eggs for monitoring, I noticed that
embryos in eggs that needed 105 days to hatch moved
and reacted to the light from the 67th day of incubation.
At the end of the incubation period the hatchlings cut
the eggshell with an egg-tooth (Fig. 2a; Fig. 3b), which
will be lost in a short time after they have completely
exited. Right after hatching the snakes weigh from 2 to
4 g (average 3.4 g) and measure from 24.5 to 29 cm. The
pattern is the same as that of the adults and will not
change with growth, only the purplish color will turn
paler when they reach sexual maturity (Fig. 2a–d). The
babies shed their skin for the first time on their 19th –21
st
day of life.
DISCUSSION
The materials and the data collected, even if based on
captive kept specimens, provide multiple information
and characteristics that help understand the different as-
pects of the biology of the species and its complete repro-
duction cycle.
Even if we don’t know a lot about the behavior and
biology of D. medici medici in nature, the compiled
records of my study prove that in captivity, in a period of
12 months, a female can mate up to 4 times and lay
3 clutches, while a male can reach the number of 6 copu-
lae in 9 months.
Additionally, despite the fact that this species has a
feeding habit specialized in bird eggs, in captivity it can
reach sexual maturity within a short time (less than one
year and half for the males).
The way of housing and the method adopted for the
husbandry of my specimens made it possible to achieve
the hatching of two captive bred generations within three
years from the acquisition of the original specimens.
If the factor of rapid growth and the ability to breed re-
peatedly per year observed in captivity were to reflect the
habits this species has in nature, it could explain the com-
monness of D. medici medici in the areas it inhabits
(Marais, 2004).
After copulation, the gestation period can be very
variable, independently from the period of the year when
the copula occurred. The collected data comprises re-
markable variations, with a minimum of 56 and a maxi-
mum of 142 days between mating and egg-laying.
The fact that one female laid a clutch consisting of
six eggs (with half of them unfertile) with no signs of
mating within the preceding 10 months may be an indica-
tion that females have the ability to preserve sperm in the
oviduct for a certain time (amphigonia retardata).
There were 2 to 6 eggs in the clutches, their size
varied between 32 × 14 and 55 × 14 mm, with an average
weight of 4 g and a maximum of 8 g. Both Branch
(1988a) and Marais (1992) refer to a case of deposition of
a clutch consisting of 6 eggs of the dimensions of
24 × 8 mm. The smaller size of the eggs of that clutch
may have been due to the dimensions and the age of the
female who laid it. In 2004 Marais describes D. medici
medici as being able to lay up to 28 eggs of the dimen-
sions mentioned above. This statement may derive from
an incorrect identification of the species, since adult
dimension of the eastern egg-eater snake would hardly
permit the presence of such a big number of eggs in its
oviducts.
From my observations the eggs can appear in differ-
ent aspects due to the diet of the female during the gesta-
tion period. This variation may be caused by the diverse
amount of calcium present in the eggs of the various bird
species. Furthermore the data regarding the incubation
values show that depending on the temperatures estab-
lished, the major part of the clutches resulted in hatch-
lings of the same sex. Additionally, depending on incuba-
tion temperatures, the incubation period varied from 69
to 105 days.
The hatchlings, after their exiting from the eggs mea-
sure from 24.5 to 29 cm and weigh from 2 to 4 g. They
share the pattern of the adults, the coloration is character-
ized by purplish shades that will fade into less striking
tones when they reach adult size. In contrast to most
other colubrid snakes, the time between pre-deposition
sheds and egg-laying in the females is shorter (only 1 – 6
days), whereas the time between hatching and first shed
of the babies is longer (19 – 21 days).
Reproduction Cycle of the Eastern Egg-Eater Snake Dasypeltis medici medici in Captivity 233
Acknowledgments. I am especially grateful to Rainer
Fesser for reviewing my study and for his precious help during
the years. A big thank goes to Marietta Grazietti for the review
of the English text.
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234 Alessandro Paterna
