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Tanzania Wildlife Research Institute
Population trends in the NCA
since 1950s to 2018
EDITORS
Emanuel Lyimo
Edward Kohi
Honori Mali
Jerome Kimaro
Machoke Mwita
Hamya Kija
Design and layout
Jerome Kimaro
Published by
The Tanzania Wildlife Research Instute
P.O Box 661
Arusha
TANZANIA
©TAWIRI, 2019
Population trends in the
NCA since 1950s to 2018
Reproducon of any part of
this document is not authorized
without a prio-wrien permission
from the copyright holder.
Funding for producon of this
document was generously
provided by The Ngorongoro
Consevaron Area Authoruty
(NCAA).
i
ii
Table of Contents
Table of contents
Introducon
Methods
Results
Wildlife biodiversity
Wildlife populaon trends inside crater
Wildlife populaon trends outside crater
People and livestock
Discussion
iii
1
2
3
3
4
8
15
18
iii
Introduction
The Ngorongoro Conservaon Area (NCA) is
globally known as a home to several rare and
endemic wildlife species, hence a biodiversity
hotspot. It shares the ecosystem with the
Serenge Naonal Park, thus promotes its
signicance in terms of tourism, research
and conservaon. Topographically, the most
remarkable feature is the Caldera (“commonly
known as crater”), currently designated as one
of the natural wonders of the world (Scoon,
2018). Addionally, the landscape is endowed
with the Olmo crater, Empaakai crater, the
Lolmalasin Mountain, the shiing sand of
Oldeani and the Olduvai Gorge archaeological
site (Parisi, Lombardo, Tang, & Mai, 2017).
Ngorongoro Conservaon Area (NCA) exhibits
unique ecological features that have favored
mulple interacons between human and
natural resources within the landscape. For
nearly 200 years, the Maasai pastoralists have
been beneng from pasturelands for their
livestock, food supply, herbal medicines and
shelter from the mother nature.
The NCA was gazeed as a protected area in
1959 (Homewood et al. 1987; NCAA 2006)
mainly to sustain the Maasai from the mother
nature while maintaining its wildlife biodiversity.
The major queson by then and now is “
what is
the limit the NCA resource could sustain before
shiing to another ecological system which
will only accomodate certain species and loose
others”
. However, sustaining the producvity of
the mother nature is an increasingly challenge
across the global and NCAA is similarly facing it
and need dynamic approaches across the me
scale.
Indeed, several studies about wildlife
biodiversity have been conducted in the NCA
like other protected areas in Tanzania. However,
to what extent their ndings have addressed
actual local conservaon needs?. “Probably
only lile“, compared to the invested eorts in
research.
Apparently, local conservaon implementers
have poor access to most of the research ndings.
One of key reason is that most of the research
ndings are published in communicaon
channels, like academic journals, which are
not an appropriate product to conservaon
managers, rangers and villagers.
Local stakeholders could be useful informants
for monitoring wildlife populaon, invesgang
surveillance of wildlife diseases and determining
causes of human-wildlife conicts. Therefore,
removing communicaon barriers to scienc
knowledge should no longer be reserved.
Failure to address this challenge could aggravate
further depleon of wildlife biodiversity and
their habitats.
Having observed this need, TAWIRI has
strategized on new communicaon approaches
that aim at simplicaon of informaon
disseminaon to conservaon ocers around
the NCA. Therefore, this booklet presents
summarized informaon based on long term
studies on wildlife and human acvies in the
NCA. It provides synthesized data on wildlife
species distribuon and populaon trends in
relaon to human acvies. It is expected that
this material could be a useful tool for planning,
monitoring and managing resource ulizaon
within the NCA.
1
Methods
A team of researchers from TAWIRI gathered diverse array of ecological and socio-economic datasets
stored at the NCAA and other potenal sources. The requested informaon was extracted from the
various source, parcularly literature, survey reports, surveys data, newsleers, published arcles,
online forums, etc as summarized in the table below (Tab.1).
Table 1: Various sources of informaon for this study
Objecve Informaon Descripon Method Disseminaon
sharing
Output
Producing
wildlife
populaon
esmate and
trend
Wildlife populaon
esmate and
trend for NCA and
where possible at a
zonal or ecological
distribuon
Wildlife biology
and populaon
informaon
from various
sources
including
TAWIRI
database,
reports and
published
literature
retrieved and
analyzed
Detailed
informaon
was gathered
and stored
in an online
digital library
Synthesized
informaon has
been distributed
as a booklet and
posters
Wildlife
populaon
esmates
and trends
produced
Establish and
analyze status
of vulnerable
wildlife species
in NCA
Idenfy, classify
and establish
populaon status
of vulnerable
species like rhino
and elephants
The team
extracted and
synthesized
all historical
and exisng
informaon of
all vulnerable
species in the
NCA
Detailed
informaon
was gathered
and stored in
online digital
library
The status report
has been produced
in a booklet and
poster
The status of
vulnerable
species in the
NCA has been
established
2
Results
Wildlife biodiversity
The NCA and its surrounding ecosystem is
home to several small and large mammal
species roaming inside and outside the
crater. A number of species are of parcular
conservaon concern by virtue of their
restricted distribuon and low populaon
status.
Sadly, however, the populaon of some of
the mammal species have been declining
or not increasing over a long period of
me. We aribute this to habitat condion
dynamics that could be inuenced by both
biophysical and anthropogenic factors.
Notably, the populaon of African bualo,
Thomson gazelle and girae have indicated
a declining trend over several past decades.
Conversely, the number of spoed hyena
has tremendously increased inside crater
compared to other carnivores.
TAWIRI in collaboraon with the NCA
connues to carry out research and
monitoring on various wildlife species and
their habitats. Although obtaining reliable
data is me-consuming, long term studies
have generated valuable informaon that
shapes the conservaon strategies from
local to internaonal levels
NCA’s conservaon focus is centered on
protecon and restoraon of wildlife
habitats, improving conservaon
awareness and provide support to various
research instuons, management
authories and local communies.
3
Wildlife populaon trend in the NCA (Inside the crater)
The long term populaon trend of bualo in
the Ngorongoro crater indicates two phases
of growth over me. The rst phase, between
1960 and 1990, indicated an exponenal
growth. Probably aributed to favourable
ecological factors. The second phase, between
1991 to 2018, showed a stable populaon trend.
This paern of populaon growth of bualo
is similar in both wet and dry season (Fig.1
and 2) even though there is a high number of
individual bualo in the crater during the wet
season than the dry season.
Buffalo
(A)
(B)
(C)
(D)
Fig 1: Wet season populaon trend (A) 1964 - 1990
(B) 1990-2018
Fig 2: Dry season populaon trend (C) 1972-1991
(D) 1991-2018
... wildlife biodiversity ...
4
The dry and wet season long term data from
1968 to 2018 for the Thomson gazelle in the
Ngorongoro Crater indicates a declining trend
with a major drop o in the early 1990s (Fig.3).
The 1990s decline have never returned back
to the 1970s populaon status. This resident
populaon seems to a further uctuaon to
the lowest in the 2000s and return to the 1990s
populaon but not early 1970s.
Thomson gazelles
(A)
(B)
Fig 3: (A) Wet season populaon trend (B) Dry season populaon trend
... wildlife biodiversity ...
5
Similar to Thomson gazelle, the populaon
status of Grant gazelle indicated declining
curves in both dry and wet season (Fig. 4).
Notably, the dry season populaon decreased
faster from 1990. Currently, the number of
individuals is less than 500.
Grant gazelles
Fig 4: (A) Wet season populaon trend (B) Dry season populaon trend
(A)
(B)
... wildlife biodiversity ...
6
Generally, both dry and wet season populaons
of wildebeest indicated a declining trend
(Fig. 5). However, the dry season populaon
indicated to stabilize in 1995 and gradually
increased thereaer.
Wildebeest
Fig 5: (A) Wet season populaon trend (B) Dry season populaon trend
(A)
(B)
... wildlife biodiversity ...
7
Wildlife populaon trend in the NCA (Outside the crater)
Eland
... wildlife biodiversity ...
8
Nearly 50% of the
populaon decreased
between the year 2000
and 2003. The populaon
remained leveled for
almost the next two
consecuve years.
Thereaer, the populaon
steadily increased by nearly
50% between the year
2006 and 2010.
Fig 7: (A) Populaon trend (B) Distribuon paern
(A)
(B)
Zebra
... wildlife biodiversity ...
9
A slight decrease in
populaon was observed in
the early 2000s. However,
from the mid-2000s, a
curve turned posive. From
2006 a sharp increase in
populaon was noted.
The populaon of Zebra
doubled between 2001 and
2018.
(A)
(B)
Fig 8: (A) Populaon trend (B) Distribuon paern
Giraffe
... wildlife biodiversity ...
10
Probably, the populaon
trend of the girae is the
saddest story.
Nearly 50% of individuals
were lost within a period of
8 to 9 years.
Unfortunately, there is no
indicaon of populaon
recovery based on recent
survey data.
Fig 9: (A) Populaon trend (B) Distribuon paern
(A)
(B)
Elephant
... wildlife biodiversity ...
11
Two obvious phases of
signicant populaon shi
were noted.
Ecosystem experienced
a sharp decrease in the
populaon between the
early 1990s and early
2000s.
In contrary, a sharp
recovery was observed
between 2005 unl recent
years. Unl 2014, 168
elephants were recorded
compared to 22 individuals
in the year 2000.
(A)
(B)
Fig 10: (A) Populaon trend (B) Distribuon paern
Buffalo
... wildlife biodiversity ...
12
Bualo populaon was the
most vulnerable compared
to other ungulates.
A slight decrease in
populaon was observed
between 1992 to 1996.
Since the early 2000s,
a sharp decrease was
observed and never
recovered. Unl 2015,
only 275 bualo remained
outside the crater.
Fig 11: (A) Populaon trend (B) Distribuon paern
Thomson gazzele
... wildlife biodiversity ...
13
The populaon of Thomson
gazelles increased between
the year 2001 and 2007
by 60 %. However, the
populaon declined by
nearly 30% unl 2010.
Fig 12: (A) Populaon trend (B) Distribuon paern
Grant gazzele
... wildlife biodiversity ...
14
A slight decrease in
populaon was observed
between the year 2000 and
2003.
Thereaer, the populaon
of Grant gazelle steadily
increased from 2008.
Unl the year 2010, the
populaon was almost
doubled compared to
records of 2002.
Fig 12: (A) Populaon trend (B) Distribuon paern
People and livestock
15
Human populaon increase in the NCA was noted since the 1950s. Despite the slight decrease in the mid-
1960s, rapid human immigraon in 1970s inuenced a sharp increase in populaon in the next 20 years.
By the early 2000s, the human populaon was already ve mes higher compared to that of 1950s.
Fig 13: Populaon esmate of people in the Ngorongoro Conservaon Area from 1954 to 2000
16
Figure 14: Established human selement inside the Ngorongoro Conservaon Area
Figure 15: Temporal changes of livestock within the NCA (a) Cale (b) Goat and sheep
17
Similarly, livestock populaon parcularly cale, sheep, and goat increased signicantly in the past six
decades. This could be aributed to the increased human populaon within NCA. It has been known that
Maasai depend less on wildlife for sustaining food security and income, thus maintaining large herds of
livestock is important for their livelihood. Nevertheless, the distribuon of livestock density around the
ecosystem varied both in me and space scale. This could be inuenced by several factors like the quality
of forage and water accessibility.
Figure 16: Distribuon of cale within the NCA between 2001 and 2010
Discussion
Compeng resource uses in the Ngorongoro crater led to the change of land uses following decreases
in grazing resource and a signicant decline in small herbivores. The analysis of long term data for grant
gazelle, Thomson gazelle and wildebeest (resident) has indicated populaon declined of herbivores within
the crater in the wet and dry season. The crater populaon of herbivore species is facing liming factors
of the populaon growth that has reduced the carrying capacity of the world largest intact caldera.
While the populaon of bualo within the crater has increased from the 1960s, its populaon growth
is stable from 1990s to date. Probably, the contribung factors have reached the threshold limit that
inuences the growth (Dublin and Ogutu 2015). The change in populaon in the crater is an indicaon of
the deteriorang of resources that can support a large number of wildlife animals. Notably, Ngorongoro
is facing an increasing invasive species within and outside the crater that aect forage availability for wild
animals as well as livestock. Invasive species can pose a signicant negave impact of carrying capacity of
the area due to the reducon of the availability of grazing resources (Macdonald and Frame 1988; NCAA
2006).
In the late 1990s and early 2000s, the UNESCO echoed their concern on the future of the property
aribung to increasing human pressure from increasing resident populaon as well as their implicaon
caused by prevailing land uses change (Debonnet and Wilson 2008). The increase of human populaon
in the NCA since the 1950s has been mainly aributed to rapid immigraon during the 1970s. The
populaon trebled in the next seven years following the severe drought that severely aected lowland
areas.
Within the crater, the populaon trend of small herbivores was high from 1960 to 1980. A signicant
decline was observed from 1990 and remained leveled for the last three decades. For example, Thomson
gazelle lost more than half of its populaon between 1960 and 1980s. On the other hand, the populaon
of Bualo increased and stabilized from the 1990s to date. Seemingly, availability of feed resources, both
during the dry and wet season, enabled to regulate the populaon of bualo in the Serenge ecosystem
(Sinclair 1974; Siclair 1977; Dublin and Ogutu 2015). The intermient drought periods from 1990 to date
and change in land use, especially increasing livestock density.
Outside the crater, it is interesng to note that the populaon of many ungulates increased exceponally
girae and bualo. This includes grant gazelle, eland, zebra, wildebeest, and elephants. Nevertheless,
eland and Thomson gazelle indicated signs of reaching the limit of populaon growth within the last two
decades.
Human populaon has been increasing faster within NCA. Given the close linkages between livelihood
and food security, there is a linear relaonship between the human and livestock populaon. However,
we envisage that these demographic changes could have exceeded the actual capacity of the ecosystem
to deliver various ecosystem services.
18
Reference
Debonnet G, Wilson E. 2008. Reacve Monitoring Mission Ngorongoro Conservaon Area (United
Republic of Tanzania. :38.
Dublin HT, Ogutu JO. 2015. Populaon regulaon of African bualo in the Mara–Serenge ecosystem.
Wildl Res. 42:382. doi:10.1071/WR14205. [accessed 2019 Jan 25].hp://www.publish.csiro.
au/?paper=WR14205.
Homewood K, Rodgers WA, Arhem K. 1987. Ecology of pastoralism in Ngorongoro Conservaon Area,
Tanzania. J Agric Sci. 108:47–72. doi:DOI:10.1017/S0021859600064133.
Macdonald IAW, Frame GW. 1988. The invasion of introduced species into nature reserves in tropical
savannas and dry woodlands. Biol Conserv. 44:67–93. doi:hps://doi.org/10.1016/0006-3207(88)90005-
5.
NCAA. 2006. Ngorongoro Conservaon Area: Management Plan 2006-2016. Ngorongoro. Sinclair ARE.
1974. The natural regulaon of bualo populaons in East Africa: The foodsupply as a regulang factor,
and compeon*. Afr J Ecol. 12:291–311. doi:10.1111/j.1365-2028.1974.tb01038.x.
Sinclair ARE. 1977. The African Bualo: A Study in Resource Limitaons of Populaons. Chicago: Chicago
University Press.
19
Appendix 1: Wildlife species survey in the crater from 1968 to 2017
Years Grant gazelle Thomson gazelle Bualo Wildebeest
1964 20,038
1968 1376 4,269
1969 1,478 3,812 18,238
1971 1,492 5,166 16,797
1972 1,105 3,216 12 15,754
1973 1,825 5,040 360 16,484
1974 1,797 4,134 80 13,366
1975 2,037 4,584 329 16,642
1976 1,450 3,419 447 18,240
1977 1,507 2,827 691 14,451
1986 2,136 3,392 1455 11,847
1987 1,135 4,677 2855 7,415
1988 2,122 7,830 2339 8,689
1989 756 2,175 859 9,152
1990 601 1,493 2,005 7,439
1991 853 4,160 2,417 7,111
1992 834 1,285 1,445 7,192
1993 696 1,071 2514 4,177
1994 796 1,169 1509 9,643
1995 1,928 1,566 1,974 5,378
1996 1,666 1,432 1,663 3,997
1997 1,517 1,582 3,656 5,648
1998 1,341 1,025 2,564 7,074
1999 1,640 1,944 3,345 16,187
2000 1,012 1,541 1,778 12,338
2001 874 1,013 1,225 13,446
2002 9,988
2003 687 769 2,314 10,939
2004 1,337 2,117 1,789 7,167
2005 704 1,453 2,511 9,251
2006 561 1,134 2,045 4,977
2007 307 1,890 1,741 10,846
2008 904 1,056 3,145 10,768
2009 646 985 2,116 8,990
2010 779 1,707 2,452 10,584
2011 326 790 2,372 6,764
2012 306 1,119 2,340 8,901
2013 747 3,189 6,482
2015 741 1,170 3,214 9,069
2017 547 1,995 1,867 9,575
20
For further informaon contact:
Director General
Tanzania Wildlife Research Instute
Box 661 Arusha,
Tanzania
Telephone: +255 (0) 27 254 9571
Website: www.tawiri.or.tz
