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The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra)
MSc Zoo Conservation Biology
Full time
2014-2015
School of Science and the Environment
Name: Michael Godfrey Wilson 14058121
Supervisor: Dr Lesley Lace
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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With the exception of any statements to the contrary, all the data
presented in this report are the result of my own efforts. In addition, no
parts of this report have been copied from other sources. I understand
that any evidence of plagiarism and/or the use of unacknowledged third
party data will be dealt with as a very serious matter.
Signed ........................................................................
Date ........................
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Abstract Humans have maintained wild animals in zoological collections for the purposes of education,
conservation, research, and recreation for many years. In captive environments, animals can
develop abnormal behaviours due to a lack of sensory stimulation. A zoo environment has to
provide opportunity for animals to carry out a wide array of their natural behaviours.
However, due to spatial and financial constraints, captive environments do not always
provide for this. Sumatran Tigers (Panthera tigris sumatra) are a particularly difficult case due
to their large natural ranges and predatory behaviours. Wild tiger populations have declined
by 97% in the past 100 years making captive breeding programmes a major focus of the zoo
community; as a result, tiger husbandry research is paramount. This study analysed the
effects on behaviour of two Sumatran tigers housed at Chester Zoo, in North West England
with respect to disturbance (visitor numbers) and noise levels.
The data in this study was collected by a focal observational sampling method of the tigers’
behaviour, every minute for 30 minutes as well as a head count of visitors and a recording
based upon the reading of a decibel reader. The behaviour displayed at the time was recorded
and later analysed using R studio. A range of behaviours were recorded and compared to
visitor numbers and noise levels. Preference of enclosure location was also determined. Noise
levels did not significantly affect behaviour whereas visitor numbers did. The animals also
preferred wooden platforms that were elevated above the ground and stayed close to dense
vegetation, where they spent over 70% of the time. The male performed almost twice as
much stereotypic pacing, 22%, than exploratory behaviour, 11%, however this was not
reflected in the female who spent no time displaying stereotypical behaviour.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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The primary objectives of this study are to determine the frequency of occurrence of resting,
exploring, and stereotypic behaviours in two captive Sumatran tigers as well as the amount
and quality of enclosure space that was utilized by the study animals. The researcher hopes
to examine the relationship between behaviours and visitor number as well as ambient noise
level.
Key Words: Zoos, Behaviour, Stereotypy, Sumatran, Tiger, Enclosure, Noise, Visitor
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Introduction There are estimated to be only 400-500 Sumatran tigers in the wild (Luo et al., 2004, 2010;
Linkie et al., 2008) and their range is much reduced and fragmented. The recent extinction of
the Caspian, Javan, and Bali subspecies and the 97% decrease of total tiger numbers since the
early 1900s (Nowell and Jackson, 1996; Kitchener and Dugmore, 2000; Luo et al., 2004)
emphasises, that tiger extinction is a very real and quickly occurring concern for conservation
and captive breeding. There are 295 registered Sumatran tigers in captivity (Luo et al., 2010),
partly due to the fact they are popular animals with the public (Luo et al., 2010). This suggests
that reintroduction could be a feasibly possible means to securing the future of the species
(Johnsingh and Madhusudan, 2009).
Tigers being large, attractive and an endangered ensures they fall very much into the category
of flagship species, making them one of the most popular zoo exhibits. This has led to the
large captive population that is seen today, which provides a great educational opportunity
regarding their conservation. It has been shown that displaying wild animals to the public can
be an effective education tool. However, it is far more effective when the animals on display
perform healthy species-specific behaviours in naturalistic-looking exhibits (Shettel-Neuber,
1988; Swanagan, 2000; Catibog-Sinha, 2008). It can also break down the conception that
humans have dominion over nature, and encourages people to view them as more than
merely a recreational display for the public.
However, some animals may develop abnormal behaviours when the captive, human-made
environment is not sufficient for the full range of instinctive, natural behaviours to be
performed (Broom, 1991; Tribe, 2003). Unfortunately zoos are often unable to provide the
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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requirements needed to allow for these behaviours due to spatial and financial constraints
(Tribe, 2003).
Over the past 40 years, a number of zoos have undertaken major changes in the husbandry
of felids to enhance their lives by incorporating environmental enrichment into the care of
the animals (Law et al., 1997; Broad and Weiler, 1998). However, effective enrichment is
difficult to develop and execute for felids due to their complex hunting behaviours and large
natural ranges. Lack of suitable enrichment and high volumes of visitors can lead to
Stereotypy (Broom, 1991; Pitsko, 2003).
Stereotypic behaviours are often considered a response to stress (Broom, 1991; Pitsko, 2003),
however this could also be the symptom of a psychological disorder. Either way, both of these
are indicators of poor welfare (Broom, 1991). Therefore, to increase welfare in captive
animals, stereotypy should be addressed. This would not only benefit the general wellbeing
of the animal, but also would increase the success of captive breeding programmes. In
addition, the delivery of the conservational and educational message and aesthetic value of
the exhibit would be enhanced. Captive breeding of endangered species aims to maintain
genetic diversity within the captive population and this is especially important for Sumatran
tigers due to their massively decreased wild population (Hutchins, 2003; Catibog-Sinha, 2008;
McGregor Reid and Zippel, 2008).
Unnatural substrate has been known to cause stereotypic behaviours in captive animals
(Hediger, 1969) and can be more uncomfortable for captive cats (Law et al., 1997). However,
some of these unnatural substrates, such as the wooden platforms are built for the purpose
of environmental enrichment, which has been, suggested to reduce abnormal behaviours.
Concrete floors are considered more hygienic due to the ease of cleaning. However, recently,
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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research has proved otherwise and so more natural substrates are now preferred by zoo
enclosure designers (Law et al., 1997).
Vegetation can help to create a more natural environment for captive animals; however, it is
difficult to replicate the vegetation of the Sumatran tigers’ natural habitat. Firstly, the habitat
in the UK is not suitable for the propagation of most Sumatran plants and the dense Sumatran
rainforest would not allow for visibility for visitors. However efforts are made regarding
vegetation in order to allow hiding areas away from the public, which also create areas of
shade (Law et al., 1997). Planting allows for more complex environments and attracts other
natural stimuli such as birds and insects (Law et al., 1997).
Tigers are avid swimmers so the availability of a pool is beneficial for their welfare. It also
provides an alternate form of exercise and enrichment as well as a means of cooling down in
hot temperatures (Bush et al., 2002).
The presence or absence of visitors may potentially influence the behaviour and location of
the animal; a busy day may result in the animal being more likely to hide away from view or
indoors (Del Thompson, 1989). One might expect that animals born into captivity will be
accustomed to visitors, and therefore not be influenced by number of humans at close
proximity, however further research is required on the behaviour of tigers in captivity, their
preferences to the captive environment and the effects of enrichment on felid wellbeing
(Pitsko, 2003).
Zoos encourage the expression of naturalistic behaviours by the animals on display, in order
to successfully assist in the delivery of their conservation and educational message (Tribe,
2003). Due to the rise in public awareness of the importance of animal welfare, stereotypic
behaviours can be aesthetically displeasing to the visiting public.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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The North of England Zoological Society is a charity based in Cheshire; Chester Zoo contains
12000 animals and 400 different species. In 2014, it was voted the best zoo in the UK, second
best zoo in Europe and sixth best zoo globally. It is a pioneer in zoo animal welfare and
husbandry, and has reputation for excelling in this role. The North of England Zoological
society is responding to the demand for more aesthetically natural and ethically minded
enclosures, having invested £40,000 to develop six hectares of land into the 'Islands' exhibit,
which is based on the South East Asian islands of Panay, Papua, Bali, Sumba, Sumatra and
Sulawesi. This is the largest zoo development to have ever occurred in Britain and will have
the largest indoor zoo exhibit in the United Kingdom. It will house 100 different species of
animal and one of the most endangered species on display will be the Sumatran Tiger. Chester
Zoo boasts approximately 1,432,867 visitors annually, making it the most visited, paid-for
attraction in UK outside of London, this is due to rise with the opening of ‘Islands’. Therefore,
animal welfare concerning numbers of visitors and noise level is an important factor to
consider in maintaining their good reputation.
This study provides recommendations for improving the welfare of captive tigers and increase
breeding success. The study of animal welfare is an important component of husbandry. This
paper adds to the literature on Sumatran tiger behaviour, which is underrepresented, despite
them being the second most common subspecies of tiger in captivity. This study also provides
useful information to Chester Zoo for the future management of the study animals, as well as
other zoo exhibit planners and animal keepers. By analysing the relationship between visitor
numbers, noise levels, animal behaviour and animal exhibit preferences, zoos will be able to
attempt to optimise certain behaviours and reduce stereotypic behaviours that are
performed by their animals whilst still allowing for an enjoyable visitor experience. These
recommendations will not only be beneficial for just Sumatran tigers but should be applicable
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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to other subspecies of tigers not included in this study as well as other large felids, such as
the jaguar and lion, also housed at Chester Zoo.
The primary objectives of this study are to determine the frequency of occurrence of resting,
exploring, and stereotypic behaviours in two captive Sumatran tigers as well as the amount
and quality of enclosure space utilized by the study animals. As well as this, the researcher
aims to examine the relationship between behaviours and visitor number as well as ambient
noise level.
This study will contribute to the species-specific literature on Sumatran tigers. The upcoming
opening of the “Islands” exhibit in Chester Zoo provides an excellent opportunity to gather
data prior to their move. These data may be used by future researchers in a comparative
study to determine the extent to which the move improves the behaviour of the animals. This
project could also provide specific recommendations for the management of captive tigers.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Methods
Study Site and Animals
Chester Zoo, in the North of England, was the data collection site for this study. Fieldwork
took place between January and September of 2015. Two individual purebred Sumatran tigers
(Panthera tigris sumatra) were the subjects of the study; one male, named Fabi, and one
female, named Kirana. Fabi and Kirana are 7 and 8 years of age respectively. They were both
born in captivity and raised by their biological parents. Fabi was born at Prague Zoological
Gardens and Kirana at Paignton Zoo Environmental Park. Fabi moved in 2009 to the enclosure
used in this study and Kirana in 2008. Both tigers have been housed continuously in this
enclosure since their moves. They have had a successful breeding history with Kirana giving
birth to three cubs in January 2015 and 2 cubs in 2013, suggesting that welfare is of a high
enough standard for breeding success.
The enclosure plan was split into various different sections depending upon the various
differing substrate, vegetation and other surface area attributes (see Figure 1) this facilitates
the collection of data and analysis. This method was also used by (Pitsko, 2003). Some
substrates, such as S1 to S7, are natural (not synthetic). Others, S7 to S16, are unnatural
(manmade). The tigers were able to fully submerge within the pond, which was constructed
out of concrete. The wooden platforms S12 to S14 were of varying heights with S12 being the
shortest and S14 being the tallest.
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Figure 1 - Sumatran Tiger Enclosure at Chester Zoo
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Variables
Data was collected using a focal observational sampling method of the tigers’ behaviour. This
is commonly used when observing the behaviours of an individual animal during a sampling
period (Altmann, 1974). During the pilot study it became evident that scan sampling was an
inappropriate method due to the size of the enclosure, and when the animals were on
opposite sides of the enclosure to one another, it was impossible to record both animals
simultaneously.
At one-minute intervals, focal samples of four variables were recorded for each animal. These
variables were: The Animal’s behaviour, The Animal location, Visitor number and Noise level
in A-weighted decibels (dBa).
Behaviours of individual animals were recorded every minute in phases of 30 minutes;
however, due to the observer collecting data consistently over the course of the day, the
phases were often back-to-back resulting in much longer continuous periods of data being
collected.
Recording took place during opening hours of the zoo and when visitors were present
between 10.30 and 18.00. Additional, unusual events, occurring in or near the exhibit were
also recorded and included keeper activity or the nearby monorail train.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Animal Behaviour and Location
The researcher classified behaviour based on an ethogram of common tiger behaviours
observed during the pilot study (Appendix 1). Much of the literature also contained common
felid behaviours and this was considered in the production of the ethogram (Lindburg, 1988;
Seidensticker and McDougal, 1993; Lyons et al., 1997). Each tiger was observed continuously
for the duration of the phase, unless it went out of sight. The behaviours were recorded on
the minute, along with the location within the enclosure that the behaviour was performed
(Figure 1). This constant observation allowed the observer to distinguish between similar
behaviours, for example walking and pacing. In order to simplify the data analysis, behaviours
were grouped into one of three distinct categories described as resting, exploratory and
stereotypic behaviour.
If more than one behaviour was displayed, for example standing and sniffing, the behaviour
with the most importance was prioritised with reference to the produced hierarchy (Appendix
1). Therefore, although the tiger is standing, which is a resting behaviour, it is also sniffing,
which is exploratory. The exploratory behaviour takes priority, in this case, so this data point
was considered as exploratory. Behaviours considered as stereotypic included pacing,
excessive grooming, tail sucking and paw chewing. However, only pacing behaviour was
witnessed during this study. The only two that could potentially apply to this study were
pacing and excessive grooming. The distinction between pacing and walking was that an
obviously, aimless walking, often back and forth, in circles, figures of eight or any other
repeatable pattern was considered pacing. Whilst walking to a separate area of the enclosure
with a purpose and not repeating was considered walking. Excessive grooming was harder to
distinguish from healthy grooming. However, due to the lack of bald patches or noticeable
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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hair loss, the study subjects would not be considered to be excessively grooming at the time
of this study.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Visitors and Noise Level
At each minute interval, a head count of the visitors visible from the position of the observer
was recorded. The visitor numbers were divided into 4 categories: Not busy - 0-4 people
looking at the enclosure, somewhat busy – 5-9 people looking at the enclosure, Busy – 10-14
people looking at the enclosure and Very busy – 15+ people looking at the enclosure.
Noise level was also included, seeing as one noisy visitor may affect the behaviour more than
10 quiet visitors. The LEMONBEST™ Mini Digital Sound Level Meter was used to measure
noise level in A-weighted decibels (dBa). Temperature was recorded using an electronic
thermometer and measured in degrees centigrade.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Results
Frequency of behaviours
During analysis, the frequency of the behavioural categories as a proportion of all behaviours
was recorded as a percentage (Table 1).
Table 1 – Time spent performing different categories of behaviour
Resting (%) Exploratory (%) Stereotypic (%)
Male 66.86 11.10 22.04
Female 87.71 12.25 0.04
Total 78.40 11.74 9.86
The male performed twice as much stereotypic behaviour than exploratory behaviour
whereas the stereotypic behaviour performed by the female was negligible. This potentially
could be due to the male having a psychological issue that results in a tendency to perform
stereotypic behaviour or alternatively could simply just be him patrolling his territory and the
observer due to the repeated nature of the behaviour recording it as stereotypic.
A comparison between the proportions seen in Table 1 and those found by Pitsko (2003) was
performed using a Chi Squared comparison of proportions test. Pitsko (2003) found that the
tigers in her sample (n=18) rested for 76% of the time, Explored for 16% of the time and
performed stereotypic behaviour for 8% of the time. The comparison was statistically similar
(Chi squared, df = 2, P = 0.44). Therefore, there is no significant difference between the two
proportions of this study and that of Pitsko (2003), suggesting that although we have a small
sample size it shows similar proportions of different types of behaviour as an experiment with
a much greater sample size.
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Breakdown of Exploratory Behaviour The difference between the types of exploratory behaviours displayed by the Male and
Female tigers are shown in Figure 2. The exploratory data was split into the specific
behaviours as recorded in the observer’s ethogram (Appendix 1). Although the total time
performing exploratory behaviours only account for 11-13% of their total behaviour observed
it would be interesting to see what proportion of their exploratory behaviour is spent
performing specific behaviours.
Figure 2 -A Comparison between the Exploratory Behaviours displayed by Male and Female Sumatran Tiger
The Female spends 38% of her total time performing exploratory behaviours positively
socialising with the cubs. The Male walks around more than the Female and also Urinates
more, this would also be expected as he is likely to be patrolling, interacting with objects and
scent marking his territory.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Preference of Location The proportion of time spent at each location was found for each tiger. This was then plotted
as a comparative bar chart (Figure 3) to determine whether there is any difference between
the male and the female preference of location. As Figure 3 shows, both tigers spent a
considerable proportion of time at S13, S14 and S16, which with reference to Figure 1, we can
see are all man-made wooden platforms. These were elevated off the ground there for would
suggest that both tigers have a preference for more 3 dimensional habitats, even if they aren’t
entirely natural. S8 was not always open, and also had poor visibility and the pond was often
not filled, which might explain the low use of these two areas. The male would patrol around
his territory and this in this case the enclosure, this is perfectly natural behaviour and may
explain why the male spends less time in a single area and is generally more spread S14 is also
the highest wooden platform where he would potentially get the best view of his territory
possibly resulting in why he took preference to this. Due to the new born cubs the female was
often somewhere that was accessible to the cubs which may explain the low use of the
highest platform S14. The female has a great preference for the mid height wooden platform,
S13, as she spent over half her time here. It may be due to it being significantly raised however
still accessible to the cubs due to a ramp.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Figure 3 - Location Preference comparison for Male and Female Sumatran Tiger
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Noise level and visitor number effects on behaviour?
Visitor number was plotted as a box and whisker graph with noise level, to determine whether
noise level increases with visitors number (Figure 4). In order to determine the statistical
significance of the differences seen in Figure 4 a Kruskal-Wallis rank sum test was performed
(Kruskal-Wallis rank sum test, 1461.41, df =3, P < 0.001). This statistically significant result
found that noise level increases with visitor number.
Figure 4 - How ambient noise level increases with visitor number
The behaviour was then compared to noise level to establish whether the behaviour was
affected by the ambient noise (Figure 5).
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Figure 5 - How ambient noise level effects different behaviours
No relationship between the ambient noise level and behaviour was found. Noise level
displayed a non-Gaussian distribution following an Anderson-Darling test (Anderson-Darling
test of normality, A = 3.66, p < 0.001), therefore ANOVA could not be used. Due to the
continuous nature of the independent variable and the nominal dependent variable, a
Kruskal-Wallis rank sum test was performed (Kruskal-Wallis rank sum test, 2.51, df = 2, P =
0.29); this suggests that noise level has no statistically significant effect on behaviour.
Behavioural categories were compared to visitor number using a Pearson chi squared test, to
determine whether the abundance of visitors have an effect regardless of their noise
(Pearson’s chi squared test, 29.8234, df = 6, P < 0.001). We can conclude that the behavioural
categories are significantly different from each other with regards to visitor number. This
could however be a result of the tiger being more visible when performing certain behaviours
thus attracting more visitors, rather than large numbers of visitors effecting the behaviour of
the tiger.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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How temperature effects behaviour and location Behaviour and location do not seem to be dramatically effected by temperature. Although,
S10 which is indoors was used considerably more when temperature was low (Figure 6 and
Figure 7). Due to the data being collected between January and September 2015 in the UK
the recorded temperatures were only between 8.7 and 23.8 degrees C which is relatively
small range of temperature and it never got above body temperature or below the freezing
point of water. Therefore it wouldn’t be expected to dramatically alter their behaviour in
these relatively mild circumstances.
Figure 6 - Temperature effect on location
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Figure 7 - Temperature effect on Behaviour
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Summary of results In summary, we found that the tigers spent the vast majority of their time resting, with
between 11-13% performing exploratory behaviours. The Male stereotyped around 22% of
the time, however the female did not stereotype at all. Of the exploratory behaviour both
tigers performed behaviours one would expect that are justifiably natural, female performed
great deal of maternal behaviour toward cubs and male performed territorial behaviour such
as scent marking and patrolling. The tigers did seem to have a preference to the elevated
wooden platforms surrounded by dense vegetation. Visitor number did seem to have a very
small effect on behaviour however it is impossible to tell whether this was visitor number
effecting behaviour or if when performing stereotypic behaviour the male tiger was more
visible thus attracting more viewers, Id Est the behaviour effecting visitor numbers rather than
the other way around. Temperature and ambient noise level had no effect upon the
behaviour and other than S10, a room indoors, being used more in colder temperatures, there
was no effect of temperature on location.
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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Discussion
In captivity an animal’s environment is dramatically different to the environment they would
experience in the wild, and they depend entirely upon humans for the provision of their daily
needs. This causes a major problem with regards to the stimulation of the individual and can
result in the development of abnormal behaviours, which may lead to a reduction in
reproductive output. As tiger populations in the wild dwindle, the necessity for healthy,
happy, reproductively successful captive populations for the use in captive breeding
programmes is of paramount importance and environmental stimulation will likely increase
captive breeding success. However, in many zoological gardens, space is limited, hunting and
mating opportunities are dramatically reduced, and various environmental components are
dependent on humans. As Chester Zoo opens its ‘Islands’ exhibit in late 2015, a major
opportunity will arise to compare the animals’ behaviour before and after the move. Also, the
data collected prior to the move, can be used to determine enclosure preference for the
tigers, and cater the new enclosure to their needs. This project can be considered a
foundation upon which to develop further research, to determine whether the move had the
expected result, and also contribute to the future management of the animals in question.
This study focused on evaluating the effects of several environmental and animal variables
on the behaviours of two captive Sumatran tigers (Panthera tigris sumatra). With a specific
interest in stereotypic pacing, due to the idea that captive carnivores often display this
behaviour when stressed. This study contributes to the small body of literature for captive
tiger management.
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A limitation was identified with the collection of visitor number data in that the observer
would only be able to see at best approximately half of the visitors surrounding the
enclosure at any time, there may well have been many more visitors on the other side of the
enclosure which were not accounted for. The enclosure was located on a major route
through the zoo, as well as being near a restaurant thus in can be assumed that the
recorded number of observers was an under estimation. The noise level may potentially
influence the behaviour and location of the animal, as well as overcoming some of the
limitations of the measurement of visitor number. Another limitation was with temperature,
the range of temperatures recorded were somewhat limited and we would expect a large
warm blooded mammal, such as a tiger, to be able to cope with this range. As a result the
behaviour wasn’t effected by the temperature, however future studies could be performed
in colder temperatures and hotter temperatures, for example the data could be collected
through the middle of both summer and winter, giving a more varied temperature range,
rather than just spring which was when the majority of data for this study was collected.
The study animals spent the majority of their time (average 78%) resting. Therefore, captive
tigers should be provided with various resting sites throughout the enclosure. Captive animals
can often have unnatural sleeping patterns due to lack of mental stimulation. This is a concern
to zoo keepers as it can be an indicator of poor welfare. However due to the nocturnal nature
of tigers, and observations only being carried out during the day time, these finding may not
be representative of typical behaviour during a 24 hour period. Further studies should be
performed overnight, and more data collected on the tiger’s behaviour throughout their
entire day. To aid this cameras could be fitted around the new enclosure which would allow
for vast quantities of behavioural data being collected throughout the day without the
The Behaviour of Captive Sumatran Tigers (Panthera tigris sumatra) | Michael Godfrey Wilson
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presence of an observer who may, especially over night when it is quiet, influence the
behaviour of the tigers.
The study animals spent around 12% of their time performing exploratory behaviour, this
however could be due to the fact that tigers are naturally nocturnal and a much greater
proportion of the time during the night could be spent exploring, when data was unable to
be collected. When broken down to more specific behaviours being displayed there was
nothing unusual. The female performed positive socialisation with the cubs for around 38%
of the time that was considered exploratory. The male walked around and urinated/scent
marked relatively more than the female. The male being more territorial and the female more
maternal is what would be expected. The male subject was observed to spend 22% of his time
performing stereotypic behaviour, which could be a cause for concern with regards to his
welfare. However, this could be partially due to the fact that a number of enrichment
activities were not being provided in order to ensure safety for the young cubs. Also, although
the Tiger performed repetitive movements as far as the observer was concerned, it could
have just been patrolling its territory which would result in the exploratory and territorial
behaviour we would expect being recorded as stereotypic behaviour. It is impossible to tell
whether this is just natural patrolling or pacing, as a result of a psychological or behavioural
issue.
Having compared the behavioural data to that of Pitsko (2003), our data was significantly
similar to the data collected in a study with a much larger sample size.
According to Margulis et al (2003), felid behaviour isn’t affected by visitor activity however
visitor activity is affected by the behaviour of felids. We found, however, a small effect
between visitor numbers and tiger behaviour, but, with Margulis et al (2003) in mind, this
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may be more likely due to the fact that when the male was stereotyping he was more visible,
and a more visible, active animal attracted more viewing visitors. From the point of view of
the visiting and paying public, it is often assumed that stereotypic behaviour is a psychological
or behavioural concern relating to welfare, and it wasn’t unusual for the observer to over hear
comments expressing concern over the welfare of the Tiger whilst it was performing this
behaviour. Therefore it is important to attempt to make the tigers more active and less
stereotypic for the purpose of visitor experience, even if it is not a welfare concern of the
animals.
Judging from the high usage of the wooden man made platforms that were constructed
around the enclosure, it can be assumed the tigers had a preference for these structures.
They spent over 70% of their time on any one of the wooden structures. These structures
were situated either in dense vegetation or in close proximity to it and were also raised off
the ground. This three dimensional element of the enclosure, along with dense vegetation,
has been described as “good quality” of enclosure space and it would be beneficial to the
tigers’ welfare if plenty of these are built around the ‘Islands’ exhibit. An additional benefit
was that they are easily visible from the public viewing areas. Thus, it is evident that an
enclosure which provides high welfare for its animal residents, can be additionally beneficial
in being aesthetically pleasing to the paying visitor.
The results of this study do not necessarily reflect the quality of the zoo or its husbandry
practices. Due to the presence of young cubs, certain enrichment which under normal
circumstances is performed regularly was unavailable at certain occasions to ensure the
safety of the cubs.
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Literature Review
The Sumatran Tiger, Panthera tigris sumatrae
The Sumatran Tiger’s geographic range is across the island of Sumatra in Indonesia (Luo et al.,
2010). There have been captive populations since 1937 and there are currently 295 registered
individuals compared to the 400-500 estimated in the wild (Luo et al., 2004, 2010; Linkie et
al., 2008). Due to their isolation on Sumatra, Sumatran tigers possess multiple unique
characters, including two diagnostic mtDNA nucleotide sites, ten mtDNA haplotypes, and 11
(out of 108) unique microsatellite alleles (Luo et al., 2010). The Sumatran tigers relatively high
genetic variability and the phylogenetic distinctiveness suggest they historically had a large
effective population size and highly restricted gene flow between the island and mainland
population (Luo et al., 2010). Like all tigers the Sumatran Tiger population is thought to be
declining as a result of habitat loss and fragmentation which is around 3.2-5.9% per year
(Achard et al., 2002; Linkie et al., 2008), this is due to expansion of oil palm plantations and
planting of Acacia plantations (Kinnaird et al., 2003; Linkie et al., 2003, 2004, 2006; Gaveau et
al., 2007). There are high levels of illegal trade in tiger parts (Nowell, 1999, 2007) and also
increasing human-tiger conflict (Nyhus and Tilson, 2004), also contributing to their decline.
History and role of Zoological Parks
A zoo is defined as any establishment where wild animals are kept for exhibition to which the
public have access, with or without charge for admission, for seven or more day in any period
of twelve consecutive months (Great Britain, 1981). Many institutions similar to this have
been documented throughout history, previously known as menageries and often used as a
display of the society’s elite.
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Within the last century, the role of the zoo has rapidly changed (Tribe and Booth, 2003;
Cuarón, 2005; Catibog-Sinha, 2008; Marino et al., 2010) becoming institutions for not only
research and recreation but also important institutions for education and conservation,
especially within urban societies. With approximately 50% of the world's population of
humans currently living in cities (Mitchell, 1998; Turley, 1999; Hutchins, 2003; Catibog-Sinha,
2008; Gusset and Dick, 2010; Marino et al., 2010), a zoological collection is one of the only
ways to experience direct contact with wildlife's diversity. As a result zoos possess the
potential to stimulate curiosity in nature and encourage its preservation (Mallinson, 2001;
Hutchins, 2003; Miller et al., 2004; Conway, 2011).
A modern zoo is now is considered an interactive, entertaining institution, more responsive
to the demand for naturally aesthetic and ethically driven animal exhibits (Tribe and Booth,
2003; Cuarón, 2005; Catibog-Sinha, 2008). This emerging role is evident in the mission
statements of many modern zoos as well as from the World Zoo Conservation Strategy
(Mallinson, 2001).
Zoos provide four key roles: Conservation, Education, Research and Recreation (Shettel-
Neuber, 1988). They assist in conservation through breeding threatened populations in ex
situ conditions (Bowkett, 2009). The role is analogous to the biblical story of Noah’s ark where
zoos can sustain populations of animals until the political or ecological cause of their decline
is resolved allowing for their eventual reintroduction (Turley, 1999; Mallinson, 2001;
McGregor Reid and Zippel, 2008; Bowkett, 2009; Conde et al., 2011). Tiger reintroduction has
proved successful in India, however to ensure its success much preparation is required and
long term management needs to be maintained to ensure that the causes of its initial decline
don’t return (Johnsingh and Madhusudan, 2009).
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A major problem with zoos is that they simply aren’t big enough (Rahbek, 1993; Mallinson,
2001; Conway, 2011). Often this results in very small, non-breeding populations being
sustained (Conway, 2011). Other problems with ex situ breeding can be maintaining genetic
integrity (Catibog-Sinha, 2008; McGregor Reid and Zippel, 2008) as well as domestication and
loss of natural behaviours (Bowkett, 2009).
Most concerning is the sheer expense, they can cost more than the equivalent in situ breeding
for mammals (Balmford et al., 1995) and often the more cost effective conservation efforts
can be overlooked if captive breeding is prioritised (Snyder et al., 1996; Bowkett, 2009).
Despite its limitations, it can be a useful and necessary conservation method under the right
circumstances and the debate has shifted to when ex situ breeding is warranted considering
it competes with in situ efforts for funding (Hutchins, 2003; McGregor Reid and Zippel, 2008;
Bowkett, 2009).
The World Zoo Conservation Strategy puts more emphasis on in situ conservation
programmes (Hutchins, 2003; Reid et al., 2008). The World Association of Zoos and Aquaria
quickly became the third largest contributor to field conservation (Conde et al., 2011; Gusset
and Dick, 2011), with the potential to become the primary non-governmental global field
conservation organisation (Hutchins, 2003; Tribe and Booth, 2003). Although zoos do
financially contribute it is relatively small amounts (Tribe and Booth, 2003; Gusset and Dick,
2010) due to financial constraints.
The combining of in situ and ex situ conservation efforts represents a great opportunity for
zoos (Mallinson, 2001; Hutchins, 2003; Gusset and Dick, 2010; Conde et al., 2011) and may be
the only hope for the survival of some species (Hutchins, 2003; Catibog-Sinha, 2008;
McGregor Reid and Zippel, 2008).
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As zoos have become more federated they are far more capable of managing their collections
as a single large collection and as a result overcome some of the problems posed by small
population size (Tribe and Booth, 2003; McGregor Reid and Zippel, 2008; Bowkett, 2009;
Conde et al., 2011). This will dramatically enhance the potential of future captive breeding
populations (Tribe and Booth, 2003).
There is a great deal of controversy around captive breeding in the conservation literature
(Rahbek, 1993; Rabinowitz, 1995), however as we progress into the Holocene extinction and
reintroduction science develops, it will play a larger role in supplementing in situ conservation
efforts (Mallinson, 2001; Conde et al., 2011; Conway, 2011).
A great deal of people agree that zoos have a great potential when it comes to educating the
general public and often it is portrayed as being the single most important contribution zoos
can make (Hutchins, 2003; Tribe and Booth, 2003; Miller et al., 2004; Patrick et al., 2007;
Catibog-Sinha, 2008; McGregor Reid and Zippel, 2008; Conway, 2011; Gusset and Dick, 2011).
However, It is also complicated to not increase the perception of human domination over
nature, when people believe the animals are confined for the visitors leisure (Kellert, 1997;
Miller et al., 2004). A well-developed educational programme with naturalistic and interactive
exhibits certainly has the potential to educate people and have a conservation impact
(Swanagan, 2000; Tribe and Booth, 2003; Miller et al., 2004; Catibog-Sinha, 2008).
Zoos are also engaging in more scientific research and offer a varied opportunities of study
(Hutchins, 2003; Catibog-Sinha, 2008; Conde et al., 2011). As a result of putting science to the
forefront of management they successfully develop husbandry and breeding methodologies
that are transferable to conservation programmes (Turley, 1999; Conway, 2011).
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If zoos want to remain economically viable they cannot forget their recreational role
(Mallinson, 2001). Most people visit a zoo for its recreational value (Mallinson, 2001) and
people who want an enjoyable day out will often be uninterested if the conservation message
is overemphasised (Turley, 1999).
What is welfare and how do zoos provide it?
Animals possess many functional systems that allow for their survival, these often require a
wide range of needs (Broom, 1991). Some of these are complex mechanisms that have
evolved in the species, such as providing environmental enrichment for sensory input (Broom,
1991).
When an animal has a need, its motivational state changes allowing for a behavioural and
physiological response that should rectify the desire (Broom, 1991). An animal employs
various coping responses that allow it to control and maintain mental and physical stability
(Broom, 1991). These are often energy intensive and therefore are rarely used unless the
normal regulatory actions fail (Broom, 1991).
Occasionally, an animal may cope with its environment and thus has adapted, sometimes this
can only be achieved with difficulty (Broom, 1991). If its natural control systems are
overloaded and it fails to cope causing a reduction in its biological fitness, it is deemed as
stressed (Broom, 1991).
Welfare comprises of the state of the individual as it attempts to cope, the extent of what has
to be done in order to cope and the success of such efforts (Broom, 1986).
Welfare can be measured using various indicators and the extent of the stresses for the
animal identified and an ethical decision can then be made to determine the welfare (Broom,
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1991). However, ethics should remain separated from a welfare assessment to ensure there
is no emotional influence and guarantee scientific integrity.
Suffering is the occurrence of an acute or prolonged unpleasant subjective feeling due to the
fact that an animal is not capable of carrying out actions required to reduce risk to its
wellbeing (Dawkins, 1990). Suffering is often associated with welfare, but welfare is a wider
term. In the absence of suffering, poor welfare can still exist. For example, stress induced
immunosuppression without the onset of disease (Kelley, 1980). If the animal is having
difficulties coping its behaviour will reflect this allowing us to somewhat quantify the suffering
and therefore realise the extent to which the welfare is poor. This highlights the importance
of observational behaviour studies in the determination of welfare. We are unable to know
the emotional feelings of an animal, however we can recognise the behavioural and
physiological responses that relate to them (Broom, 1991).
Suffering is the emotional feelings, which are unknown and also subjective. Welfare has to
incorporate other factors, as it is not scientifically sound to define welfare just in context of
the level of assumed suffering (Broom, 1991).
Frustration is when an animal knows how to interact with the environment however is
prevented from doing so, this can result in abnormalities in physiology and results in
behavioural changes, which can be indicators of welfare (Broom, 1991). It can be very difficult
for an animal to cope if it has evolved to explore and respond to various stimuli once kept in
an enclosure that doesn’t have a sufficient space or varied enrichment (Broom, 1991).
Sensory deprivation is well known for leading to various behavioural abnormalities (Broom,
1991; Tribe, 2003).
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The biological fitness of an animal can indicate welfare (Broom, 1991). Biological fitness is
often defined as the animal’s lifetime reproductive success. However, in zoos, breeding
programme coordinators dictate which individuals will breed in order to maintain genetic
diversity therefore actual biological fitness will be impossible to truly determine.
An abnormal behaviour is a behaviour that differs in pattern, frequency, or context from that
shown by the majority of the species in conditions that allow a full range of behaviour (Broom,
1991). The behaviour of the animal will change to deal with the environmental difficulty,
therefore should only be unusual or short lived experiences. Sometimes, the abnormal
behaviour can develop into a behavioural pathology which no longer processes a beneficial
effect and can potentially harm the perpetrator.
An example of abnormal behaviour that is common in zoos is stereotypy. This is a repeated
sequence of movements that has no obvious purpose (Dantzer, 1986; Mason, 1991; Pitsko,
2003; Tribe, 2003). Stereotypies are commonly seen in situations which are frustrating,
threatening or unstimulating (Broom, 1991; Pitsko, 2003). It seems likely that they are
pointless, energetically expensive signs of psychological pathology (Dantzer, 1986). The more
often the stereotypy is displayed and the length of time the stereotypic behaviour lasts, the
worse the welfare.
There are three major factors that has encouraged change throughout the zoo industry:
The development of zoo legislation and codes of practice,
The development of more suitable captive animal exhibits
Improvements in husbandry and veterinary care.
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Most countries around the world have some form of legislation for zoological collections
(Cooper, 2003), that ensure basic provisions are provided for. Zoo enclosure development has
gone through 3 distinct phases over the past 150 years (Shettel-Neuber, 1988):
First generation exhibits – which consist of barred cages which were common in the
pre 20th century zoos. Often held animals in isolation and had limited facilities.
Second generation exhibits – generally larger and constructed out of concrete or
cement, containing animals within a moat or chain link fence. Facilities were more
suitable and allowed renovation. Common around the early to mid-20th century.
Third generation exhibits – larger still and often attempting to replicate the animal’s
natural habitat. Often more immersive to visitors, whilst avoiding welfare issues.
Common from mid-20th century to present (Tribe, 2003).
The various zoo associations that have formed encourage zoos to become members and thus
allow industry self-regulation through the development of codes of conduct and risk of
expulsion from the association.
Research into animal husbandry has massively increased welfare in zoos, resulting in many
cases animals that have higher life expectancy in captivity than in the wild (Kirkwood, 2003).
Regardless the scrutiny of zoos is greater than ever, resulting in the zoo industry attempting
to scrupulously excel in animal welfare, struggling with limited space and still maintaining a
financially viable business. Thorough the understanding of the effect of captivity upon the
behaviour of animals, manipulation of enclosure space and husbandry practices can improve
welfare (Tribe, 2003).
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Zoos in the United Kingdom generally consider the Royal Society for the Prevention of Cruelty
to Animals Five Freedoms (Brambell, 1965) as the minimum to its provision of welfare which
state:
Freedom from hunger or thirst
Freedom from discomfort
Freedom from pain, injury or disease
Freedom to express normal behaviour
Freedom from fear and distress
It is in the interest of zoos to ensure high standards of welfare, as an animal displaying
naturalistic behaviours in an environment that mimics its natural one will aid in the delivery
of its conservational and educational messages as well as being more aesthetically pleasing
for the recreation.
Zoos attempt to deliver high welfare through various forms of environmental enrichment.
Environmental enrichment is a practice that enhances the quality of the captive environment
in order to promote optimal psychological and physiological well-being (Mellen and
Shepherdson, 1997). In practice there are four forms of environmental enrichment (Tribe,
2003):
Physical enrichment - providing toys, smells, objects, water features and develop the
enclosure to increase the accessible surface area.
Social enrichment - more suitable sex ratios, increased group size or mixed species enclosures.
Feeding enrichment - incorporates a challenge to the acquisition of food.
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Conditioning enrichment - bonding between the animal and its keeper, provides cognitive
enrichment and allows for the keeper to easily achieve certain husbandry tasks (Shepherdson,
2003).
The emphasis is that the quality of space provided is considerably more important than the
quantity. Due to the fact that the determining factor of space used in the wild is that which is
required to acquire the resources necessary to maximise biological fitness. Seeing as these
are provided for in zoos the desire to disperse over large distances will likely be reduced
(Tribe, 2003).
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Acknowledgements
I would like to take this opportunity to thank all of those who have provided support and
direction throughout the entire process of developing this thesis. In particular, I would like to
express my sincere gratitude Dr Lisa Holmes and Chester Zoo for allowing me to conduct my
research at their institution as well as providing me with useful materials and assistance. I
would also like to thank Dr Lesley Lace of Manchester Metropolitan University, for all her
constructive criticism and support as my academic mentor. I would like to express gratitude
to Dr Martin Jones and Dr Edwin Harris of Manchester Metropolitan University for all of their
support throughout the production of this thesis. I would like to thank Mrs Maire Wilson,
who, whilst not in the best of health, still found the time and energy to proof read the project
for me. Finally my deepest gratitude extends to Ms Alexa Vargas who has assisted not only
financially but also with moral support throughout the year.
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Appendix Appendix 1 - Recorded behaviours, their descriptions, categories and priorities