Hermann`s tortoise

Hermann’s tortoise
(Testudo hermanni)
in Serbia
About the Project
This publication was produced within the
project “Distribution and conservation of
Hermann’s tortoise (Testudo hermanni
boettgeri) in Serbia”, financed by the Rufford
foundation.
The goal of this project is to establish the actual distribution of the Hermann’s tortoise in
Serbia, to assess the state of its populations,
and to gather basic morphometric data and
DNA samples for future studies.
Other than field research, the project implies
various educational activities: lectures, informative posters, brochures, etc.
For more information about the project,
please visit:
www.rufford.org/rsg/projects/ana_golubović.
Text:
Ana Golubović,
research assistant;
Sonja Đorđević,
Research Associate
Faculty of Biology, University of Belgrade;
Serbian Herpetological Society ”Milutin
Radovanović“
Technical preparation:
Sonja Đorđević
Printing was financed by the Project.
Hermann’s tortoise
(Testudo hermanni)
in Serbia
Basic species’ characteristics, endangering
factors and guidelines for future investigation
Ana Golubović, Sonja Đorđević
Prepared within the project
“Distribution and conservation of Hermann’s tortoise (Testudo hermanni boettgeri) in Serbia”,
financed by the Rufford foundation
2013
Photographs and illustrations sources:
Except where stated otherwise, the photographs used for this publication were made by the members of the Serbian Herpetological Society “Milutin Radovanović” and colleagues from similar organizations and institutes: Marko Anđelković (pages 4, 5), Ana Golubović (pages 11, 13), Sonja
Đorđević (pages 1, 2, 3, 4, 8, 12), Vuk Iković (page 6) and Xavier Bonnet (page 14).
Hermann’s tortoise ( Testudo hermanni )
Where do the chelonians
live?
There are approximately 300
species of chelonians known in the
world. They live on all continents
(except the Antarctica), on land and
in salt- and fresh water.
Entire species’ distribution: white circles = western subspecies, T. hermanni hermanni; black
circles = eastern subspecies, T. hermanni boettgeri (from Fritz et al., 2006: A rangewide
phylogeography of Hermann’s tortoise, Testudo hermanni (Reptilia: Testudines: Testudinidae): implications for taxonomy. Zoologica Scripta, 35: 531–543).
In Serbia, Hermann’s tortoises live south of the Danube and Sava
Rivers. They typically inhabit hills and plains, open spaces with sparse
bushes, and oak forests. These tortoises are omnivores, which means that
they feed mostly on plants, but also consume mushrooms and carrion.
Hermann’s tortoise is an endemic species
In nature, Hermann’s tortoises live only in Europe, and nowhere else in the world! Considering the decline of populations in Western Europe, Serbia and the surrounding
countries are the last refuge for this species. If we don’t protect Hermann’s tortoises in
the Balkans, they may become extinct.
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Like other reptiles in regions
under temperate climate, Hermann’s tortoises are active during warmer parts of
the year. From the beginning of November until the beginning of March they fall
into a state of inactivity (hibernation).
After hibernation, tortoises intensively
feed and start searching for mates. Reproductive activities are common from
spring to early autumn, with peaks in late
spring and late summer. Females usually
lay four to six eggs in nests dug in the
ground. Juveniles hatch after two months
of incubation. The gender of young tortoises depends on thermal conditions
during incubation: temperatures above
31.5°С “produce” females, while in
colder nests more males develop.
The sex of immature individuals
is almost undetectable superficially
(based on external morphology), i.e. sexually dimorphic characters usually develop only after the age of ten. In adult
tortoises gender is easily distinguishable
by the shape and size of the shell and tail.
The figures depict a female
(left) and a male Hermann’s tortoise (right), viewed from their ventral and dorsal sides.
Differences between the sexes in
the shape of their shells are clearly
visible: female shells are oval, while
those of males are trapezoidal;
males’ tails are larger and possess
a large horny spur on their tips
(upper right). In addition, fully grown
males are smaller than mature females.
2
Juvenile tortoises are difficult to observe in nature. They have a lot of
potential natural predators hence they spend most of their time in shelters.
Their shell hardens at the age of four, thus juveniles represent potential meals
even to relatively small predators such as cats, dogs and birds (crows, magpies
and even shrikes). Because of the pliable shell and absence of other anti-predator mechanisms, many tortoises don’t reach maturity: mortality rates of juveniles are very high. Adults are well protected by the rigid and highly domed
shell, and hardly any animal can harm them (e.g. pigs/wild boars and badgers).
Tortoises grow
throughout their life
Tortoises, like other reptiles, continuously grow during their entire life.
Growth rates are the highest in juvenile
tortoises; the mature ones grow much
slower. If there is an unlimited supply of
food, e.g. on farms, adult tortoises continue their fast growth, thus can reach
twice the size of those in nature!
The approximate age of tortoises living in temperate climates can be
assessed by the number of growth rings on the horny plates of their shells.
Growth rings form during activity periods, while gaps between them form during hibernation. Age at maturation can also be assessed: after reaching maturity,
tortoises’ growth rate drops drastically and growth rings become narrow. Males
reach maturity at the age of 6–14, and females at 7–16 years. Chelonians are
one of the longest-living vertebrates. On average, tortoises reach ages of 30–
80 (up to 150 years in Galapagos tortoises).
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Tortoises and humans
Juvenile Hermann’s tortoises are charming creatures. Sometimes people
can’t resist bringing them home (from the wild) for pets. However, when such tortoises grow up, their owners often get bored, and release them into nearby forests.
Unfortunately, this is often a huge mistake. First, taking tortoises from nature damages the original populations, which are very sensitive to declines in numbers; second, releasing tortoises into an unknown and inappropriate place can also
compromise their existence. Tortoises left in the environment with no other tortoises
will never have an opportunity to reproduce, thus such animals are as good as dead.
A tortoise left in an environment inhabited with other tortoises, but far from its original population, can easily introduce exotic parasites and disturb the balance in the
genetic structure of the host population. If you really like tortoises, it would be
best to enjoy their company in their natural habitats.
Tortoises travelled to space
Tortoise tissues are
not curative
Tortoises, along with mealworms and fruit
flies, are the first animals ever to have
been in space. Scientists of the Soviet
Union sent these animals around the
Moon on September 14th 1968. Seven
days later the shuttle returned and the tortoise passengers were alive! Although
they lost 10% of body mass, they were active and with their good appetite. This was
one of first proofs that animals can survive
voyage to the space.
Contrary to deep-rooted beliefs, tortoise
tissues are not curative. Tortoises are
prone to bacterial, viral and fungal infections, as are all other animals. Often they
host large numbers of parasites contagious to humans. Additionally, tortoises
commonly feed next to agricultural land
and near roads, thus their blood and meat
contain pesticides and heavy metals.
4
Unfortunately, people sometimes destroy tortoise nests, mistaking them for
the snake nests. As a matter of fact, they are easy to distinguish. Tortoise eggs are
spherical, with hard, calcified shells, similar to pigeon eggs. Snake eggs, on the other
hand, are elongated, with soft leathery shells. It is good to know that poisonous
snakes living on the Balkan Peninsula are viviparous, i.e. they do not lay eggs. Therefore, even if you do find a snake’s nest, it can only be a nest of some of the common
non-venomous colubrid species. Colubrid snakes feed mostly on small rodents, and
can’t harm humans. On the contrary, they can only be useful to people, regulating
populations of rodents around human settlements, just like cats! However, if you
don’t want any snakes in your neighborhood and you like tortoises, you can send us
photos of the nest and we will see to which group it belongs, and we’ll find a solution
together.
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Hermann’s tortoise is endangered
The gravest threats to Hermann’s tortoises are human activities: agriculture and urbanization, which lead to fragmentation and destruction of habitats, as well as traffic and collecting (for pets, food and “medicaments”).
Prolonged maturation, low numbers and high mortality of juvenile tortoises
make these animals prone to rapid extinction, even during a one year period,
when exposed to one of the above-mentioned factors.
Collecting tortoises from nature can easily lead to the extinction of a
given population. It is proven that removal of 11% of adult individuals is fatal
for the population. Adult females are especially important for the population
viability. High mortality and slow maturation of juvenile tortoises disable population recovery after catastrophic events.
6
Although historical and contemporary research about Hermann’s tortoises in Serbia are rare, known facts are stunning. Federal Statistical Office
noted export of over two million tortoises from former Yugoslavia, in a time
span of only 40 years during the 20th century. This enormous number is similar
to the number of inhabitants of Belgrade, the capital of Serbia. Clearly, tortoise
populations in former Yugoslavia were very dense and numerous. Considering
the biology of the species, this uncontrolled collecting in a comparatively short
time period probably led to the extinction of numerous populations.
Hermann’s tortoise distribution in former Yugoslavia, according to literature data and recent investigations (from Ljubisavljević et al., 2011.
Commercial export of the land tortoises (Testudo
spp.) from the territory of the former Yugoslavia: a
historical review and the impact of overharvesting
on wild populations. North-Western Journal of Zoology 7: 250-260).
The other subspecies of Hermann’s tortoise (Testudo hermanni hermanni) inhabits Western Europe. Despite considerable scientific and financial
efforts to conserve these animals, their numbers persistently decrease. Available data imply significantly better conditions of the Balkan populations, but
data of areal and population size are insufficient both in Serbia and the surrounding countries. Except long-term studies in Greece (1970–2000), there
were only a couple of studies on Hermann’s tortoises in the Balkan Peninsula,
almost 30 years ago.
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People in Serbia and the neighbouring countries often
see tortoises in nature. Therefore, since it is a common
species, we don’t have the feeling that the Hermann’s tortoise
is endangered, but in fact the Balkan Peninsula is its last resort! Our goal is to continue and expand the comprehensive
studies of tortoises in Serbia, and help people realize the
problems of tortoises in their surroundings. Considering its
comparatively good condition, the preservation of T. hermanni in Serbia requires a moderate effort and financial support – we just need to protect their habitats in the present
state, and find a way to stop tortoises disturbing and poaching.
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Hermann’s tortoise - protected species
Although the Hermann’s tortoise is protected
with national and international laws, the problem of its uncontrolled, illegal collecting from
nature remains an open question. For example,
during the preceding decade, on the borders between Serbia and EU countries, the customs
services confiscated tortoises on several occasions (e.g. 500 individuals in 2005, and 200 in
2007).
Several years ago the first farm of Hermann’s
tortoises was registered in Serbia, with all the
necessary permits for collecting, breeding and
export. There are 1,200 adult individuals in this
farm; only the young hatched at the farm are
eligible for selling and export (with the CITES
and other permits).
Unauthorized breeding and selling of Hermann’s tortoises is illegal. Even for scientific
research, with professional handling and minimal harassment, permits from the competent
Ministry are necessary.
Unauthorized persons are not allowed to:
• capture or in any other way harass tortoises
from nature;
• kill tortoises or sample their tissues;
• sell individuals or their body parts (e.g.
eggs, shells, meat etc.).
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Any violation of these prohibitions should be reported to
competent institutions:
- Local inspection authority
- Republic environmental protection inspection
Belgrade
Dr Ivana Ribara 91, 11070 Novi Beograd
Phone: +381112157-997 (08:30 – 16:30)
- Institute for Nature Conservation of Serbia
Belgrade Headquarters
Dr Ivana Ribara 91, 11070 Novi Beograd
Phone: +381112093-801, +381112093-802
(8:00 – 16:00)
E-mail: beograd@zzps.rs
Department in Niš
Vožda Karađorđa 14, 18000 Niš
Phone: +38118523-448 (8:00 – 16:00)
E-mail: nis@zzps.rs
10
Maybe you didn’ t know:
How long do the
chelonians exist?
According to fossil records, the
first chelonians lived more than
220 million years ago. Compared
to chelonians, modern humans
are evolutionary young organisms, existing for merely 200
thousand years – a thousand
times shorter!
A fossil of Odontochelys semitestacea (from Li et al. 2008. An ancestral turtle
from the Late Triassic of southwestern China.
Letters to Nature, 456: 497-501).
Who are the closest
relatives of chelonians?
For a long time it was thought
that the closest living relatives of
chelonians are lizards and
snakes, considering their morphology. However, new genetic
research proved that tortoises
are more closely related to crocodilians and birds.
Extant tortoises
don’t have teeth
On the left: one of the possible positions of tortoises in the reptilian “family tree”
(from: Сао et al. 2000. Phylogenetic position of
turtles among amniotes: evidence from mitochondrial and nuclear genes. Gene, 259: 139-148).
Jaws of extant tortoises are covered with hard keratin (the same
protein your fingernails are composed of) which forms a beaklike
“sheath” – they don’t have teeth.
With their powerful bite tortoises
rip off parts of food and swallow
them without chewing.
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What do the tortoises do in the morning?
Tortoises, like other reptiles, must raise their body temperature in order to
“wake”. In most of the cases they heat up by basking. In this way they
raise their metabolic functions (e.g. digestion) and only afterwards start
feeding or patrolling their territory.
Tortoises do produce
sounds
Male Hermann’s tortoises make
high-pitched noise during courting
and mating. Scientists hypothesise
that these noises could be a product of mating effort, sort of communication with females or a kind of
signal to rival males.
Tortoises always find
their way back home
Although they seem as inactive,
clumsy animals, tortoises possess
remarkable orientation and travelling skills. It was shown that tortoises unmistakably find the way
back to their primary habitat shortly
after being translocated.
12
What is the chelonian shell made of?
Bony elements of the shell develop from the overgrown vertebrae, ribs,
pectoral girdle and small bony elements originating independently in the
skin: the shell is the external skeleton of chelonians, thus they can’t get
out of it. The outer surface of the shell is covered with horny (keratinous)
plates. Although the shell is relatively heavy (i.e. energy-consuming) to be
carried around all the time, it represents a secure shelter, at least for adult
tortoises. When a tortoise is completely retracted in the shell, hardly any
animal can harm it.
13
Tortoise shells are
sensitive to touch
Hermann’s tortoise is not
highly social
Tortoises can feel the pressure on
their shell, just like you can feel a
pressure on your fingernails. This
allows them to retract in the shell
on the first sign of danger.
Tortoises living in nature can rarely
be seen in company of other tortoises. Even hatchlings are completely independent. Only during
reproductive season it is possible to
see couples or males fighting for a
female.
Female tortoises store sperm in their oviducts
During the reproductive season females usually mate with several
males, therefore the progeny of several fathers can be found in a single clutch. It is proven that females can store sperm in oviducts,
keeping it viable for up to four years! In other words, females can lay
fertilized eggs four years after the last mating. It was suggested that
females choose mates by visual, tactile and auditory cues before
mating occurs, but sperm competition (post-copulatory sexual selection) also occurs.
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