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Observations in a snake
habitat in the Val Mustair
Authors: Jesper Angelin, Bladins Gymnasium, Malmo, Sweden
Merlin Hochreutener, Gymnasium St. Antonius, Appenzell
Switzerland
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Tutor: Hans Schmocker
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2014-06-26
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Abstract
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Snake habitats found in the montane region of Val Mustair (Switzerland) usually serve as suitable
sites for observing the venomous Asp viper (Vipera aspis) and the non-venomous Smooth snake
(Coronella austriaca). Having received information about what was believed to be a snake habitat
in the Val Mustair region, we aimed to enhance our understanding of the area by defining the
species in the habitat, the number of individuals, the typical habitat characteristics, the daily
activities above ground, the available prey and, if any, possible interactions between the species.
During the three days of field work we observed two Vipera aspis and two Coronella austriaca.
Regarding the activity patterns, results revealed that the snakes tend to be basking during the
morning and afternoon but are rarely seen in the middle of the day if air temperatures reach more
than 20°C. Humidity, vegetation, branch piles and stone structures also proved to be significant
factors with direct impact on snake behavior and ecology. In addition, the different species were
observed basking together, a somewhat rare phenomenon that is not yet fully understood but
further investigated in this report.
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Keywords: Vipera aspis, Coronella austriaca, snake ecology, snake habitat, Val Mustair
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This in order to enhance our understanding of
1. Introduction"
the two species’ behavior and ecology. Hence!
forth, we specifically aimed to determine the
The Swiss Alps host a variety of reptiles where
some viviparous species can be found at
altitudes even as high as 2800 m.a.s.l. In the
Val Mustair (Switzerland), the Asp viper
(Vipera aspis) and the Smooth snake
(Coronella austriaca) are two commonly found
viviparous species. Both prefer dry and warm
habitats with stones suitable for basking.
Vipera aspis mainly feeds on mice, lizards and
frogs while the Coronella austriaca prefers
Slow worms (Anguis fragilis) and lizards.
Mature animals shed the skin two to three
times a year and the average length of local
Vipera aspis adults is 60 cm but Coronella
austriaca adults frequently reach 70 cm. The
Vipera aspis can usually be identified by its
characteristic broad triangular head where the
snout is slightly but distinctly upturned. When
identifying the Coronella austriaca one should
note the small head, the grey-brown colour
and the small dark spots or characteristic
blotches presented on the back.1
Based on earlier observations of both
Coronella austriaca and Vipera aspis in a
defined area2, we decided to investigate more
about what was believed to be a snake habitat.
1
2
different species in the habitat, the number of
individuals, the typical habitat characteristics,
the daily activities above ground, the possible
interactions between the species (if more than
one) and the available prey.
According to our hypothesis which was
partly based on rumors concerning the habitat,
we initially believed that the habitat hosted
both species and at least two individuals.
Furthermore, it was thought to be an area
exposed to solar radiation during most hours
of the day and populated by mice and frogs.
Regarding the daily activity we believed that
both species were most active during the
morning hours and in the afternoon. However,
as an additional prediction we presumed that if
any interactions occurred during our three
days of field work, they were going to be
hostile.
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Arnold Nicholas, Reptiles and Amphibians, page 232-234
In order to protect the habitat, no maps of the area are published.
2014-06-26
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2. Materials and methodology
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2.1 Locating habitat and snakes
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Without given coordinates we searched for
snakes with binoculars on three spots (see
figure 1 for details) close to the rumored
observation site during five hours of the first
day of excursion. Once snakes were spotted
and subsequently identified using Arnold
Nicholas field guide ”Reptiles and Amphibians”3, hotspots were marked out and
searched for snakes every hour but for no
more than 30 minutes in order to minimize
possible disturbance. Due to field work
limitations and sun hours we decided to search
for snakes from 08:00 to 18:00 on the 23rd,
24th and 25th of June.
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2.2 Counting, activity analysis and interactions
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Every time a snake was observed, pictures
were taken and further analysed. By comparing pictures, individuals were distinguished
and counted. Observing individuals simultaneously also assisted in confirming the total
number in the habitat. In the end of the study
attempts to collect all the observed snakes
were made for determination of sex and
identification marks. To determine the daily
activity and influencing factors, such as
weather conditions and temperatures, all
observation times as well as above mentioned
factors were dokumented every hour. Any
observed interactions between the species
were photographed and analyzed.
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2.3 Habitat and prey
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In order to identify typical characteristics of a
habitat, two genuine hotspots were compared
with a similar spot where no snakes had been
observed. By photographing and analyzing the
differences between these spots, the distinguished characteristics of the habitats favored
by the snakes emerged.
3
With no resources to do a proper analysis of
the mammals in the area, only sighted ones
were photographed and counted.
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3. Results
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3.1 Habitat characteristics and available prey
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Results obtained from analyzing the different
spots indicated on both similarities and
differences outlined in figure 1 and 2.
However, snakes were only observed in the
first two spots which had branch piles, dry
stone structures and frequent illumination as
common denominators. Although spot three
had similar stone structures to the other spots,
these were covered with moss, resulting in an
increased humidity.
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Figure
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Spot 2
Spot 3
Illumination Frequent
Frequent
Less
frequent
Humidity
Dry
Dry
Quite wet
Typical
structures
Branch
piles, large
and varied
stone
structures,
high grass
but sparse
vegetation!
, river
Branch
piles, large
and varied
stone
structures,
high grass
but sparse
vegetation!
, river
No branch
piles, large,
varied and
moss
covered
stone
structures,
no high
grass but
quite dense
vegetation
Available
prey
sighted
2 frogs
2 frogs
1 mouse
Number of
individuals
observed
1 Asp Viper! 1 Asp Viper!
1 Smooth
1 Smooth
Snake
Snake
Arnold Nicholas, Reptiles and Amphibians, page 47, 48
2014-06-26
Spot 1
0
Dense
Vegetation Sparse
Figure 2
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Interestingly the Vipera aspis B was seen
more times basking during very warm
conditions compared to the other snakes.
When comparing the activity between the two
species it is evident that Vipera aspis
individuals were mostly seen throughout the
day and more times than the Coronella
austriaca individuals. The activity of the
Coronella austriaca species showed a tendency to be restricted to the later hours of the
day.
Spot 2
Spot 1
Spot 3
Wet
Dry
Humidity
3.2 Individuals identified and their activity
patterns
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Frequent observations and idle search
revealed the presence of one Vipera aspis and
one Coronella austriaca thriving at spot one (A
snakes) and a second Vipera aspis and a
second Coronella austriaca thriving at spot 2
(B snakes). The Vipera aspis A, B and the
Coronella austriaca B were the only snakes
caught for determination of sex and identification marks. After having detected eggs in
all three snakes they were identified as gravid females. Only speculations regarding the
sex of the Smooth Snake A were made.
Results further revealed some specific and
relatively clear activity patterns above ground.
The period from 15:00 to 18:00 proved to have
the highest observation frequency during the
three days of research (see figures 3,4 and 5).
However, the activity above ground also
proved to be highly dependent on the weather
conditions and air temperature. For instance
only Vipera aspis B was observed during rainy
weather conditions (see figure 3). On the other
hand the snakes favored basking at air
temperatures around 17-19 degrees and
especially during cloudy and slightly unstable
weather. During sunny water with air
temperatures reaching above 19 degrees few
snakes were found in general.
The individuals that were observed during
these conditions were often covered by
branches or high grass.
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!Figure 3
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!Figure 4
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Observed activity
Monday 23rd of June 2014
Coronella austriaca B
Coronella austriaca A
Vipera aspis B
Vipera aspis A
Daily time
08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
Temperature in shade/°C ?
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?
20.0 21.0 20.0 18.5 19.3 19.3 19.7
18.0
Weather conditions
Sunny Sunny Sunny Sunny Sunny Cloudy Rainy Rainy Sunny Sunny Sunny
Observed activity
Tuesday 24th of June 2014
Coronella austriaca B
Coronella austriaca A
Vipera aspis B
Vipera aspis A
Daily time
08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
Temperature in shade/°C 12.5 14.5 15.9 17.3 17.2 17.5 14.3 17.0 17.0 13.6
13.6
Weather conditions
Cloudy Cloudy Cloudy Sunny Cloudy Cloudy Rainy Cloudy Cloudy Rainy Rainy
2014-06-26
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!Figure 5
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Observed activity
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3.3 Interactions between the species !
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Wednesday 25th of June 2014
Coronella austriaca B
Coronella austriaca A
Vipera aspis B
Vipera aspis A
Daily time
08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00
Temperature in shade/°C 10.0 10.7 12.1 12.7 18.2 19.9 20.6 19.5 19.4 19.1
18.6
Weather conditions
Rainy Cloudy Cloudy Cloudy Sunny Sunny Sunny Cloudy Cloudy Sunny Sunny
At 16:00 on the 24th of June, Vipera aspis A
and Coronella austriaca A were observed at
spot 1, basking together on the same stone
with close contact but without any hostile
interaction (see figure 6). At 16:00 on the 25th
of June, Vipera aspis B and Coronella
austriaca B were observed at spot 2, also
basking together without any hostile interaction
(see figure 7).!
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Figure 6
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C.a. A
V.a. A
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Figure 7
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C.a. B
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V.a. B
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It is important to emphasize that this study was
a small study where only binoculars were used
for observation of snakes. Thus, one should
bear in mind that some snakes might have
been active above ground while still being out
of sight. Consequently, this possible error
might have affected the results to a certain
degree. Therefore, the conclusions drawn in
this section should not be considered entirely
conclusive. However, considering the habitat
characteristics and typical structures of spot 1
and spot 2, we now better understand why
snakes were not found in spot 3. Primarily, the
difference in vegetation between the first two
spots and spot 3 proved to be a crucial
distinguishing factor. Snakes require frequent
solar radiation hence they are more likely to be
found in dry places like spot 1 and 2 without
sun-blocking obstacles such as trees. It is
possible that the moss, covering the stones at
spot 3 prevented the snakes from thriving
since it contributes to a more humid
microclimate. Such microclimates tend to
consistently have lower temperatures than dry
microclimates. It is common that snakes prefer
dry and sun exposed places near a stretch of
water which compresses the amplitude of the
temperature (spot 1 and 2). These microclimates also enable the snakes to adapt its
position to the current weather conditions and
therefore preserve a relatively unchanged
body temperature. Something that was
supported by our results. Secondarily, the
branch piles are believed to play an important
role since they can function as cover while still
allowing the snakes to bask in the sunlight that
is let through. The temperature of the
branches is also lower than the temperature of
the stones which can reach up to 60 °C and
that is too hot for the snakes. Hence, the
branches also help prevent the snakes from
becoming overheated.
When studying the snakes activity patterns
above ground it was evident that they were
highly dependent on the weather conditions.
Because reptiles are cold-blooded animals
they prefer warm weather conditions which
allows them to come out and bask to regulate
4. Discussion
2014-06-26
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their body temperature.4 Therefore it is not
surprisingly remarkable that we often observed
snakes during the sunny hours of the day.
Likewise, during rainy weather conditions the
snakes had to move to a sheltered place, often
underground. Measurements of the temperature indicated on a major air temperature
decrease of up to 6 degrees Celsius when it
started to rain. However, the ground temperature stayed relatively unchanged and even
higher than the air temperature during these
conditions. Due to this fact most snakes went
underground in order to preserve their
increased body temperature.
Amazingly only the Vipera aspis B could be
observed basking during the whole Wednesday even though the sun was shining quite
firmly, giving rise to air temperatures of up to
20,6 degrees Celsius. Eventually when this
snake was collected for further investi-gation
she indisputably proved to be a high gravid
female. Gravid viviparous snakes are required
to absorb as much solar radiation as possible
for their eggs to develop. Consequently, they
repeatedly go to the same places to bask.
Although the Vipera aspis A and the Coronella
austriaca B also were believed to be females,
they were not seen basking during these
warmer conditions. One suggestion why this
was not the case might be due to the fact that
they were mistakenly identified as females or
that they had not reached the same stage of
gravidity as the Vipera aspis B.
Another surprising phenomenon was the
interactions between the Vipera aspis species
and the Coronella austriaca species. They
were basking very close to each other. The
Coronella austriaca and the Vipera aspis are
sometimes seen basking close together when
they are gravid. Experts speculate whether
such accumulations only occur in places with
very favorable microclimate, places where only
females of the two species thrive or if it is just
a general phenomenon. Suggestions of why it
occurs might deal with the fact that the snakes
perplex predatory birds or that they assist each
other in temperature regulations.5
In conclusion this study has provided
general information of a specific snake habitat
in the Val Mustair, enhancing our understanding of snake behavior and ecology in the
montane region. Most predictions regarding
the habitat and activity times were proved to
be correct with the exception of the prediction
regarding the interactions. Further research in
this genre should, in our opinion, therefore aim
to focus on why the Coronella austriaca and
the Vipera aspis interact in the way they do
and why there were no signs of aggression
during these interactions.
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Acknowledgements
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First and foremost we would like to thank The
Swiss Foundation of Young Scientists which
organized the International Wildlife Research
Week in Valchava. It gave us the opportunity
to explore and research the nature and wildlife
found in the alpine climate. We would also like
to express our gratitude towards the reptile
specialist Hans Schmocker who inspired us to
work with reptiles and provided most useful
guidance during the project.
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References"
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Meyer Andreas / Silvia Zumbach / Benedikt
S c h m i d t / J e a n - C l a u d e M o n n e y, A u f
Schlangenspuren und Krötenpfaden,
Amphibien und Reptilien der Schweiz; ISBN:
978-3-258-07874-8; second edition 2014;
page, 42-43, 72-73!
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Nicholas Arnold, Reptiles and Amphibians,
page 47-48, 232-234, second edition
published 2002, Collins!
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4
Andreas Meyer, Auf Schlangenspuren und Krötenpfaden, Amphibien und Reptilien der !
Schweiz, page 42-43
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Andreas Meyer, Auf Schlangenspuren und Krötenpfaden, Amphibien und Reptilien der !
Schweiz, page 72-73
2014-06-26