Guest post from Dr Joseph Ogutu of the Bioinformatics Unit at Hohenheim University.
Richard, thanks for highlighting this issue and trying to be as objective as possible. Here are facts you did not consider or did not know about that support the BBC report and paint a gloomy picture of the Mara unless something is urgently done.
The aerial survey data are very variable because they are a small sample of the entire population due to financial constraints. However, they do reveal the correct trends as several independent analyses have shown. We acknowledge this variability by averaging counts over several years in the 1970s and 2000s in calculating the declines in wildlife numbers to minimize the influence of random errors. We actually say so in our paper. The data gaps are due to financial constraints and this will continue to be a limitation even in the future. Several studies have tested the reliability of this method and showed it to be reliable.
At least six other peer-reviewed and independent scientific publications, by very different authors, listed below, have reported extreme wildlife declines in the Mara region of Kenya since 1977. So, it is not true that “finding other research studies to corroborate ours will have been hard”. I have included abstracts from these papers, which speak for themselves, so I need not add anything more. Another paper that is preparation shows that buffalo numbers in the Mara Reserve dropped by 76% during the drought of 1993. They were about 13000 in 1993 but by 1994 their number had declined to under 3000. This is reported in the paper by Joseph Ogutu and others published in the Journal of Zoology in 2009 and by Ottichilo and others in 2000, details of their publication are given below. The buffalo decline is based on an independent biannual aerial surveys conducted by the World Wide Fund for Nature (WWF) from 1984 to 1995 and continued by the Kenya Wildlife Service (KWS) thereafter. The numbers in the Reserve have not increased to more than 4500 since. Buffalo were virtually wiped out of the Mara ranches during that drought and they have all but disappeared there. Yet, in Serengeti where the same drought killed about 40% of the buffaloes, numbers have been increasing rapidly (See K. L. Metzger, ARE. Sinclair, Ray Hilborn, J Grant C. Hopcraft and Simon AR Mduma. Biodiversity Conservation (2010) 19:3431–3444. DOI 10.1007/s10531-010-9904-z). So, why is this? So, it is not generally correct to assert that crashes occurred only in the 1980s when numbers continue to decline dramatically even today. Regarding the wildebeest migration, 12 monthly surveys conducted from December 1978 to November 1979 found an average of 800000 wildebeest in the Mara Region (see below).
Unfortunately, there are no counts of wildlife numbers in the Mara conservancies, other than the ones we used, which show declines. So, there would be no factual basis to assert that wildlife are not declining, are level or growing sustainably in the conservancies. That is what we would wish to be the case but at present, most of the wildlife in the conservancies may have just moved from other areas in the ecosystem where the situation is worse or is getting worse. Thus, even though I fully support the conservancies, they would need to monitor their wildlife first before we can make definitive assessments.
Also, the oldest conservancy in the Mara ranches, in the sense the word is being used today in the Mara, has been in existence since about 2005/2006, which is not enough to assess changes in numbers of long-lived species. This is not to say that wildlife are finding the much needed refuge in these conservancies.
The wild dogs became extinct in the Mara in the mid 1990s and the new ones seen there are just sporadic visitors from the Serengeti or Loliondo in Tanzania, or wherever else, without which there would still be no wild dog in the Mara, so the BBC report is accurate. The roan antelope also became extinct in the Mara in the late 1970s, but unlike wild dogs, none has come from outside the Mara region ever since. The conservancies hold the promise to improve the future of wildlife in the Mara and should be supported. I also agree that some are doing a lot to improve management and conservation of wildlife. The Mara Conservancy deserve special mention in this regard, especially for fighting poaching hard in the last decade and for publishing their work online. We all need to support the conservancies to save the wildlife and improve local livelihoods but require them to, at the very least, monitor wildlife and regularly report their counts in publicly accessible websites, so we all can see and be convinced that they are having a positive impact. At present this is not the case. The Mara region is perhaps one of the very few such complex ecosystems in the world that is being “managed” without a management plan. There is a need to act now and not to live in perpetual denial that the situation is dire. With all these warnings from all scientists that have worked on this issue, what else would we nee to decide it is time to act?
Here are two recent such empirical tests of the reliability of the Aerial survey methodology used to count wildlife by the Department of Resource Surveys and Remote Sensing of Kenya (DRSRS).
1. Ottichilo WK. African Journal of Ecology 1999, Vol. 37, pages 435-438 (DOI: 10.1046/j.1365-2028.1999.00199.x). Comparison of sample and total counts of elephant and buffalo in Masai Mara, Kenya
Abstract. Both aerial transect sample counts and total counts of elephant and buffalo were conducted in the study area during the wet season. The results from the two counting methods were tested for significant difference. The test showed that the results were not significantly different for both the elephant (P > 0.05) and buffalo (P > 0.05).
2. Wilber K. Ottichilo, Wilson M. Khaemba. African Journal of Ecology 2001, Vol. 39, pages 45-50 (DOI: 10.1111/j.1365-2028.2001.00268.x). Validation of observer and aircraft calibration for aerial surveys of animals
Abstract. Calibration procedures to determine strip widths for use by the Department of Resource Surveys and Remote Sensing (DRSRS) in its aerial surveys are validated by statistical analysis. Tests were made for differences in observer, aircraft and between using photography (camera) and direct observation (naked eye) in the determination of strip widths on the ground. The relationship between strip widths measured on the ground and in the air was determined using regression analysis. Tests were also made for differences between population estimates reported by DRSRS and those recalculated using reported strip widths for elephant, kongoni, wildebeest and cattle. There appears to be no significant differences between observer performance and between reported and recalculated population estimates for all species except cattle. A significant difference was found between strip widths obtained by photography and those through direct observation, with photography values being 14% higher at ground level. Strip widths measured while the aircraft was in the air were highly correlated to those measured while on the ground (r = 0.97). Overall, it can be concluded that the DRSRS standardization of observers, calibration of the aircraft and calculation of population estimates were carried out correctly. Finally, it is recommended that the difference in strip widths determined from photography and through direct observation needs to be considered in the final calculation of population estimates.
Here are the six publications providing additional scientific evidence of extreme wildlife declines in the Mara region of Kenya since 1977 that preceded the two recent papers by Joseph Ogutu et al. But first, the wildlife numbers in the Mara region of Kenya in 1978-79 based on 12 monthly surveys.
John G Stelfox, Donald G. Peden, Helmut Epp, Robert J Hudson, Susan W Mbugwa,
Jasphat L Agatsiva, Charles L Amunyunzu. Journal of Wildlife Management, vol 50, pages 339-347. Herbivore dynamics in Southern Narok, Kenya.
Abstract. Monthly counts of large herbivores on the rangelands of southern Narok District were conducted by the Kenya Rangeland Ecological Monitoring Unit (KREMU) from December 1978 to November 1979. At that time these rangelands supported year-long herbivore populations of 132/km2 representing a biomass of 160 kg/ha. The Mara Plains, particularly the area protected as the Masai-Mara National Reserve, served as a critical dry season range. During the peak of the dry season (Jul), the resident population of 100,000 blue wildebeest (Connochaetes taurinus) was supplemented with large migratory herds from the Serengeti which increased total numbers to >800,000. Burchell's zebras (Equus burchelli) and Thomson's gazelles (Gazella thomsoni) were less migratory but moved seasonally through the Mara, Siana, and Loita range units.
1. Wilber K. Ottichilo, Jan De Leeuw, Andrew K. Skidmore, Herbert H. T. Prins.
African Journal of Ecology 2000, vol. 38, pages 202-216 (DOI: 10.1046/j.1365-2028.2000.00242.x). Population trends of large non-migratory wild herbivores and livestock in the Masai Mara ecosystem, Kenya, between 1977 and 1997.
Abstract. The total of all non-migratory wildlife species in the Masai Mara ecosystem has declined by 58% in the last 20 years. This decline ranges from 49% in small brown antelopes to 72% in medium brown antelopes. In individual wildlife species, the decline ranges from 52% in Grant's gazelle to 88% in the warthog. Declines of over 70% have been recorded in buffalo, giraffe, eland and waterbuck. Only elephant, impala and ostrich have not shown any significant decline or increase. Overall, there has not been any significant difference in decline of all wildlife population sizes inside and outside the reserve, except for Thomson's gazelle and warthog. Livestock have not significantly declined over the entire analysis period. However, livestock and cattle populations significantly declined during the 1983–88 period. Donkey declined by 67%, while shoats (goats and sheep) remained stable. In the case of wildlife, land use and vegetation changes, drought effects and poaching are considered to be among the potential factors that may have been responsible for the decline; the decline in livestock during the 1983–84 period was probably due to drought effects.
2. Wilber K. Ottichilo, Jan de Leeuw, and Herbert H.T. Prins. Biological Conservation
Volume 97, Issue 3, February 2001, Pages 271-282 (Doi:10.1016/S0006-3207(00)00090-2|). Population trends of resident wildebeest [Connochaetes taurinus hecki (Neumann)] and factors influencing them in the Masai Mara ecosystem, Kenya.
Abstract. Population trends of resident wildebeest (Connochaetes taurinus hecki (Neumann)) and factors influencing them in Masai Mara ecosystem between 1977 and 1997 were investigated. Population trends were analyzed using aerial census data collected through systematic reconnaissance flights. Aerial censuses pertaining to resident wildebeest populations (non-migratory) were identified from migratory populations through spatial analysis. Regression analysis was used for population trend analysis. The impact of land use changes on wildebeest population was analyzed by comparing changes in wildebeest densities in cropped and non-cropped areas. Relationship between population size and rainfall fluctuations was used to assess the influence of rainfall on trends. Comparison of cattle densities in cropped and non-cropped areas was used to get an insight into possible competition between cattle and wildebeest for food. The results show that resident wildebeest population in the Masai Mara ecosystem has declined from about 119,000 in 1977 to about 22,000 in 1997, an 81% decline. The decline is mainly attributed to loss of former resident wildebeest wet season grazing, calving and breeding ranges to agriculture. Rainfall fluctuations and possible competition between wildebeest and cattle during periods of limited food resources may have further contributed to the decline.
3. K. Homewood, E. F. Lambin, E. Coast, A. Kariuki, I. Kikula, J. Kivelia, M. Said, S. Serneels, and M. Thompson. Proceedings of the National Academy of Sciences of America, October 23, 2001 vol. 98 no. 22 12544-12549 (doi: 10.1073/pnas.221053998). Long-term changes in Serengeti-Mara wildebeest and land cover: Pastoralism, population, or policies?
Abstract. Declines in habitat and wildlife in semiarid African savannas are widely reported and commonly attributed to agropastoral population growth, livestock impacts, and subsistence cultivation. However, extreme annual and shorter-term variability of rainfall, primary production, vegetation, and populations of grazers make directional trends and causal chains hard to establish in these ecosystems. Here two decades of changes in land cover and wildebeest in the Serengeti-Mara region of East Africa are analyzed in terms of potential drivers (rainfall, human and livestock population growth, socio-economic trends, land tenure, agricultural policies, and markets). The natural experiment research design controls for confounding variables, and our conceptual model and statistical approach integrate natural and social sciences data. The Kenyan part of the ecosystem shows rapid land-cover change and drastic decline for a wide range of wildlife species, but these changes are absent on the Tanzanian side. Temporal climate trends, human population density and growth rates, uptake of small-holder agriculture, and livestock population trends do not differ between the Kenyan and Tanzanian parts of the ecosystem and cannot account for observed changes. Differences in private versus state/communal land tenure, agricultural policy, and market conditions suggest, and spatial correlations confirm, that the major changes in land cover and dominant grazer species numbers are driven primarily by private landowners responding to market opportunities for mechanized agriculture, less by agropastoral population growth, cattle numbers, or small-holder land use.
4. Suzanne Serneels and Eric F Lambin. Journal of Biogeography, vol. 28, pages 391-407.
Impact of land-use changes on the wildebeest migration in the northern part of the Serengeti-Mara ecosystem
Abstract. Aim. The study tests the hypothesis that land-use changes in Narok District have had an impact on the wildebeest population [Connochaetes taurinus mearnsi (Burchell)] in the northern part of the Serengeti-Mara ecosystem. Location The Serengeti-Mara ecosystem is a vast area of rangelands, straddling the Tanzanian-Kenyan border in East Africa. The area is home to some 1.3 million wildebeest, of which some 30,000 animals currently reside in the Kenyan part of the ecosystem. Methods We analysed the temporal changes in the wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem and their relationship with possible driving forces of change, such as rainfall, normalized difference vegetation index (NDVI), livestock numbers and land-cover changes. Changes in the spatial distribution of wildebeest for three periods were compared with spatial changes in livestock distribution and land cover. The analyses were repeated for the Tanzanian part of the ecosystem and results compared. We thus tested the relative importance of land-use changes among the different potential driving forces of change in the wildebeest populations. Results The wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem declined drastically over the past 20 years and is currently fluctuating around an estimated population of 31,300 animals, which is about 25% of the population size at the end of the 1970s. The wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem has, over the last decades, been controlled by food supply during the dry and the wet seasons. Expansion of large-scale mechanized wheat farming in the Loita Plains since the early 1980s has drastically reduced the wildebeest wet season range, forcing the wildebeest population to use the dryer rangelands in the south-eastern part of the Loita eco-unit, or to move to the Mara eco-unit, where competition with cattle is higher. The expansion of the farming area has not influenced the size of the total cattle population in the Kenyan part of the study area, nor its spatial distribution. The much larger migratory wildebeest population of the Serengeti, in Tanzania, has not been affected by a downward trend from the late 1970s and is regulated by food supply in the dry season (Mduma et al., 1999). Around the Serengeti, in Tanzania, land-use changes are much less widespread, occur at a lower rate and affect a much smaller area compared with the Kenyan part of the ecosystem. Moreover, land-use changes around the Serengeti have taken place away from the main migration routes of wildebeest. Conclusions Over the last decades, the decline in the Kenyan wildebeest population did not seem to affect the much larger Serengeti wildebeest population. However, if more land were to be converted to large scale farming closer to the Masai Mara National Reserve, the dry season range for both the Kenyan and the Serengeti population would be reduced. This might have serious consequences for both populations and therefore for the entire Serengeti-Mara ecosystem.
5. Mike Norton-Griffiths. WORLD ECONOMICS • Vol. 8 • No. 2 • April–June 2007.
How Many Wildebeest do You Need?
A paragraph from the paper, since I could not find the abstract.
Bad news from the rangelands
1977 was an important year for conservation in Kenya for it was then that
sport hunting and all other consumptive uses of wildlife and attendant
value added activities were banned. It was also the year when the Kenya
Rangeland Ecological Monitoring Unit (KREMU) began to monitor the
numbers and distribution of livestock and wildlife throughout the 500,000
km2 of Kenya’s arid and semi-arid rangelands.
So, perhaps uniquely, a major change in conservation policy—a ban on
all consumptive utilisation of wildlife—coincided with a new capacity to
monitor its effect and impact.
The monitoring results have been deeply disturbing, and by the mid-
1990s a number of warnings were issued about a major decline in wildlife
right across Kenya’s rangelands, even in the most heavily used tourist
areas. The only good news was that loss rates seemed significantly less
inside the Protected Areas than outside where some 70% of all Kenya’s
wildlife are to be found. More recent analyses eliminate even this ray of
hope—rates of wildlife loss continue unchecked, and are now the same
both inside and outside the Protected Areas. Since 1977, Kenya has lost
60%–70% of all its large wildlife.
While losses of such magnitude indicate a major institutional failure to
protect wildlife, the pernicious spread of agriculture throughout the rangelands,
even around important conservation and tourism areas like the Mara
area of Narok and the Amboseli area in Kajiado, give clear signals of a policy
failure. Indeed, the entire economic system of rangeland production in
Kenya has undergone a radical transformation since the mid-1970s
(Figure 2): the human population is growing at >3% per annum; cultivation
is growing at >8% per annum; while livestock numbers remain stable,
offtake is growing at >4% per annum; and wildlife is decreasing by >3%
per annum.
From the perspective of the individual pastoral landowner, at the
macro-economic scale domestic and international markets are expanding
and there are real gains in producer prices. At the micro-economic scale,
the pastoral landowner sees improved market and transport networks,
improved market information networks (mobile telephone coverage is
expanding across the rangelands), improved access to financial services,
ever-increasing opportunities for off-farm jobs and investment,1 and a
wider availability and choice of goods and services.
6. Western D, Russell S, Cuthill I (2009). PLoS ONE 4(7): e6140. doi:10.1371/journal.pone.0006140. The Status of Wildlife in Protected Areas Compared to Non-Protected Areas of Kenya.
Abstract
We compile over 270 wildlife counts of Kenya's wildlife populations conducted over the last 30 years to compare trends in national parks and reserves with adjacent ecosystems and country-wide trends. The study shows the importance of discriminating human-induced changes from natural population oscillations related to rainfall and ecological factors. National park and reserve populations have declined sharply over the last 30 years, at a rate similar to non-protected areas and country-wide trends. The protected area losses reflect in part their poor coverage of seasonal ungulate migrations. The losses vary among parks. The largest parks, Tsavo East, Tsavo West and Meru, account for a disproportionate share of the losses due to habitat change and the difficulty of protecting large remote parks. The losses in Kenya's parks add to growing evidence for wildlife declines inside as well as outside African parks. The losses point to the need to quantify the performance of conservation policies and promote integrated landscape practices that combine parks with private and community-based measures.
Richard, thanks for highlighting this issue and trying to be as objective as possible. Here are facts you did not consider or did not know about that support the BBC report and paint a gloomy picture of the Mara unless something is urgently done.
The aerial survey data are very variable because they are a small sample of the entire population due to financial constraints. However, they do reveal the correct trends as several independent analyses have shown. We acknowledge this variability by averaging counts over several years in the 1970s and 2000s in calculating the declines in wildlife numbers to minimize the influence of random errors. We actually say so in our paper. The data gaps are due to financial constraints and this will continue to be a limitation even in the future. Several studies have tested the reliability of this method and showed it to be reliable.
At least six other peer-reviewed and independent scientific publications, by very different authors, listed below, have reported extreme wildlife declines in the Mara region of Kenya since 1977. So, it is not true that “finding other research studies to corroborate ours will have been hard”. I have included abstracts from these papers, which speak for themselves, so I need not add anything more. Another paper that is preparation shows that buffalo numbers in the Mara Reserve dropped by 76% during the drought of 1993. They were about 13000 in 1993 but by 1994 their number had declined to under 3000. This is reported in the paper by Joseph Ogutu and others published in the Journal of Zoology in 2009 and by Ottichilo and others in 2000, details of their publication are given below. The buffalo decline is based on an independent biannual aerial surveys conducted by the World Wide Fund for Nature (WWF) from 1984 to 1995 and continued by the Kenya Wildlife Service (KWS) thereafter. The numbers in the Reserve have not increased to more than 4500 since. Buffalo were virtually wiped out of the Mara ranches during that drought and they have all but disappeared there. Yet, in Serengeti where the same drought killed about 40% of the buffaloes, numbers have been increasing rapidly (See K. L. Metzger, ARE. Sinclair, Ray Hilborn, J Grant C. Hopcraft and Simon AR Mduma. Biodiversity Conservation (2010) 19:3431–3444. DOI 10.1007/s10531-010-9904-z). So, why is this? So, it is not generally correct to assert that crashes occurred only in the 1980s when numbers continue to decline dramatically even today. Regarding the wildebeest migration, 12 monthly surveys conducted from December 1978 to November 1979 found an average of 800000 wildebeest in the Mara Region (see below).
Unfortunately, there are no counts of wildlife numbers in the Mara conservancies, other than the ones we used, which show declines. So, there would be no factual basis to assert that wildlife are not declining, are level or growing sustainably in the conservancies. That is what we would wish to be the case but at present, most of the wildlife in the conservancies may have just moved from other areas in the ecosystem where the situation is worse or is getting worse. Thus, even though I fully support the conservancies, they would need to monitor their wildlife first before we can make definitive assessments.
Also, the oldest conservancy in the Mara ranches, in the sense the word is being used today in the Mara, has been in existence since about 2005/2006, which is not enough to assess changes in numbers of long-lived species. This is not to say that wildlife are finding the much needed refuge in these conservancies.
The wild dogs became extinct in the Mara in the mid 1990s and the new ones seen there are just sporadic visitors from the Serengeti or Loliondo in Tanzania, or wherever else, without which there would still be no wild dog in the Mara, so the BBC report is accurate. The roan antelope also became extinct in the Mara in the late 1970s, but unlike wild dogs, none has come from outside the Mara region ever since. The conservancies hold the promise to improve the future of wildlife in the Mara and should be supported. I also agree that some are doing a lot to improve management and conservation of wildlife. The Mara Conservancy deserve special mention in this regard, especially for fighting poaching hard in the last decade and for publishing their work online. We all need to support the conservancies to save the wildlife and improve local livelihoods but require them to, at the very least, monitor wildlife and regularly report their counts in publicly accessible websites, so we all can see and be convinced that they are having a positive impact. At present this is not the case. The Mara region is perhaps one of the very few such complex ecosystems in the world that is being “managed” without a management plan. There is a need to act now and not to live in perpetual denial that the situation is dire. With all these warnings from all scientists that have worked on this issue, what else would we nee to decide it is time to act?
Here are two recent such empirical tests of the reliability of the Aerial survey methodology used to count wildlife by the Department of Resource Surveys and Remote Sensing of Kenya (DRSRS).
1. Ottichilo WK. African Journal of Ecology 1999, Vol. 37, pages 435-438 (DOI: 10.1046/j.1365-2028.1999.00199.x). Comparison of sample and total counts of elephant and buffalo in Masai Mara, Kenya
Abstract. Both aerial transect sample counts and total counts of elephant and buffalo were conducted in the study area during the wet season. The results from the two counting methods were tested for significant difference. The test showed that the results were not significantly different for both the elephant (P > 0.05) and buffalo (P > 0.05).
2. Wilber K. Ottichilo, Wilson M. Khaemba. African Journal of Ecology 2001, Vol. 39, pages 45-50 (DOI: 10.1111/j.1365-2028.2001.00268.x). Validation of observer and aircraft calibration for aerial surveys of animals
Abstract. Calibration procedures to determine strip widths for use by the Department of Resource Surveys and Remote Sensing (DRSRS) in its aerial surveys are validated by statistical analysis. Tests were made for differences in observer, aircraft and between using photography (camera) and direct observation (naked eye) in the determination of strip widths on the ground. The relationship between strip widths measured on the ground and in the air was determined using regression analysis. Tests were also made for differences between population estimates reported by DRSRS and those recalculated using reported strip widths for elephant, kongoni, wildebeest and cattle. There appears to be no significant differences between observer performance and between reported and recalculated population estimates for all species except cattle. A significant difference was found between strip widths obtained by photography and those through direct observation, with photography values being 14% higher at ground level. Strip widths measured while the aircraft was in the air were highly correlated to those measured while on the ground (r = 0.97). Overall, it can be concluded that the DRSRS standardization of observers, calibration of the aircraft and calculation of population estimates were carried out correctly. Finally, it is recommended that the difference in strip widths determined from photography and through direct observation needs to be considered in the final calculation of population estimates.
Here are the six publications providing additional scientific evidence of extreme wildlife declines in the Mara region of Kenya since 1977 that preceded the two recent papers by Joseph Ogutu et al. But first, the wildlife numbers in the Mara region of Kenya in 1978-79 based on 12 monthly surveys.
John G Stelfox, Donald G. Peden, Helmut Epp, Robert J Hudson, Susan W Mbugwa,
Jasphat L Agatsiva, Charles L Amunyunzu. Journal of Wildlife Management, vol 50, pages 339-347. Herbivore dynamics in Southern Narok, Kenya.
Abstract. Monthly counts of large herbivores on the rangelands of southern Narok District were conducted by the Kenya Rangeland Ecological Monitoring Unit (KREMU) from December 1978 to November 1979. At that time these rangelands supported year-long herbivore populations of 132/km2 representing a biomass of 160 kg/ha. The Mara Plains, particularly the area protected as the Masai-Mara National Reserve, served as a critical dry season range. During the peak of the dry season (Jul), the resident population of 100,000 blue wildebeest (Connochaetes taurinus) was supplemented with large migratory herds from the Serengeti which increased total numbers to >800,000. Burchell's zebras (Equus burchelli) and Thomson's gazelles (Gazella thomsoni) were less migratory but moved seasonally through the Mara, Siana, and Loita range units.
1. Wilber K. Ottichilo, Jan De Leeuw, Andrew K. Skidmore, Herbert H. T. Prins.
African Journal of Ecology 2000, vol. 38, pages 202-216 (DOI: 10.1046/j.1365-2028.2000.00242.x). Population trends of large non-migratory wild herbivores and livestock in the Masai Mara ecosystem, Kenya, between 1977 and 1997.
Abstract. The total of all non-migratory wildlife species in the Masai Mara ecosystem has declined by 58% in the last 20 years. This decline ranges from 49% in small brown antelopes to 72% in medium brown antelopes. In individual wildlife species, the decline ranges from 52% in Grant's gazelle to 88% in the warthog. Declines of over 70% have been recorded in buffalo, giraffe, eland and waterbuck. Only elephant, impala and ostrich have not shown any significant decline or increase. Overall, there has not been any significant difference in decline of all wildlife population sizes inside and outside the reserve, except for Thomson's gazelle and warthog. Livestock have not significantly declined over the entire analysis period. However, livestock and cattle populations significantly declined during the 1983–88 period. Donkey declined by 67%, while shoats (goats and sheep) remained stable. In the case of wildlife, land use and vegetation changes, drought effects and poaching are considered to be among the potential factors that may have been responsible for the decline; the decline in livestock during the 1983–84 period was probably due to drought effects.
2. Wilber K. Ottichilo, Jan de Leeuw, and Herbert H.T. Prins. Biological Conservation
Volume 97, Issue 3, February 2001, Pages 271-282 (Doi:10.1016/S0006-3207(00)00090-2|). Population trends of resident wildebeest [Connochaetes taurinus hecki (Neumann)] and factors influencing them in the Masai Mara ecosystem, Kenya.
Abstract. Population trends of resident wildebeest (Connochaetes taurinus hecki (Neumann)) and factors influencing them in Masai Mara ecosystem between 1977 and 1997 were investigated. Population trends were analyzed using aerial census data collected through systematic reconnaissance flights. Aerial censuses pertaining to resident wildebeest populations (non-migratory) were identified from migratory populations through spatial analysis. Regression analysis was used for population trend analysis. The impact of land use changes on wildebeest population was analyzed by comparing changes in wildebeest densities in cropped and non-cropped areas. Relationship between population size and rainfall fluctuations was used to assess the influence of rainfall on trends. Comparison of cattle densities in cropped and non-cropped areas was used to get an insight into possible competition between cattle and wildebeest for food. The results show that resident wildebeest population in the Masai Mara ecosystem has declined from about 119,000 in 1977 to about 22,000 in 1997, an 81% decline. The decline is mainly attributed to loss of former resident wildebeest wet season grazing, calving and breeding ranges to agriculture. Rainfall fluctuations and possible competition between wildebeest and cattle during periods of limited food resources may have further contributed to the decline.
3. K. Homewood, E. F. Lambin, E. Coast, A. Kariuki, I. Kikula, J. Kivelia, M. Said, S. Serneels, and M. Thompson. Proceedings of the National Academy of Sciences of America, October 23, 2001 vol. 98 no. 22 12544-12549 (doi: 10.1073/pnas.221053998). Long-term changes in Serengeti-Mara wildebeest and land cover: Pastoralism, population, or policies?
Abstract. Declines in habitat and wildlife in semiarid African savannas are widely reported and commonly attributed to agropastoral population growth, livestock impacts, and subsistence cultivation. However, extreme annual and shorter-term variability of rainfall, primary production, vegetation, and populations of grazers make directional trends and causal chains hard to establish in these ecosystems. Here two decades of changes in land cover and wildebeest in the Serengeti-Mara region of East Africa are analyzed in terms of potential drivers (rainfall, human and livestock population growth, socio-economic trends, land tenure, agricultural policies, and markets). The natural experiment research design controls for confounding variables, and our conceptual model and statistical approach integrate natural and social sciences data. The Kenyan part of the ecosystem shows rapid land-cover change and drastic decline for a wide range of wildlife species, but these changes are absent on the Tanzanian side. Temporal climate trends, human population density and growth rates, uptake of small-holder agriculture, and livestock population trends do not differ between the Kenyan and Tanzanian parts of the ecosystem and cannot account for observed changes. Differences in private versus state/communal land tenure, agricultural policy, and market conditions suggest, and spatial correlations confirm, that the major changes in land cover and dominant grazer species numbers are driven primarily by private landowners responding to market opportunities for mechanized agriculture, less by agropastoral population growth, cattle numbers, or small-holder land use.
4. Suzanne Serneels and Eric F Lambin. Journal of Biogeography, vol. 28, pages 391-407.
Impact of land-use changes on the wildebeest migration in the northern part of the Serengeti-Mara ecosystem
Abstract. Aim. The study tests the hypothesis that land-use changes in Narok District have had an impact on the wildebeest population [Connochaetes taurinus mearnsi (Burchell)] in the northern part of the Serengeti-Mara ecosystem. Location The Serengeti-Mara ecosystem is a vast area of rangelands, straddling the Tanzanian-Kenyan border in East Africa. The area is home to some 1.3 million wildebeest, of which some 30,000 animals currently reside in the Kenyan part of the ecosystem. Methods We analysed the temporal changes in the wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem and their relationship with possible driving forces of change, such as rainfall, normalized difference vegetation index (NDVI), livestock numbers and land-cover changes. Changes in the spatial distribution of wildebeest for three periods were compared with spatial changes in livestock distribution and land cover. The analyses were repeated for the Tanzanian part of the ecosystem and results compared. We thus tested the relative importance of land-use changes among the different potential driving forces of change in the wildebeest populations. Results The wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem declined drastically over the past 20 years and is currently fluctuating around an estimated population of 31,300 animals, which is about 25% of the population size at the end of the 1970s. The wildebeest population in the Kenyan part of the Serengeti-Mara ecosystem has, over the last decades, been controlled by food supply during the dry and the wet seasons. Expansion of large-scale mechanized wheat farming in the Loita Plains since the early 1980s has drastically reduced the wildebeest wet season range, forcing the wildebeest population to use the dryer rangelands in the south-eastern part of the Loita eco-unit, or to move to the Mara eco-unit, where competition with cattle is higher. The expansion of the farming area has not influenced the size of the total cattle population in the Kenyan part of the study area, nor its spatial distribution. The much larger migratory wildebeest population of the Serengeti, in Tanzania, has not been affected by a downward trend from the late 1970s and is regulated by food supply in the dry season (Mduma et al., 1999). Around the Serengeti, in Tanzania, land-use changes are much less widespread, occur at a lower rate and affect a much smaller area compared with the Kenyan part of the ecosystem. Moreover, land-use changes around the Serengeti have taken place away from the main migration routes of wildebeest. Conclusions Over the last decades, the decline in the Kenyan wildebeest population did not seem to affect the much larger Serengeti wildebeest population. However, if more land were to be converted to large scale farming closer to the Masai Mara National Reserve, the dry season range for both the Kenyan and the Serengeti population would be reduced. This might have serious consequences for both populations and therefore for the entire Serengeti-Mara ecosystem.
5. Mike Norton-Griffiths. WORLD ECONOMICS • Vol. 8 • No. 2 • April–June 2007.
How Many Wildebeest do You Need?
A paragraph from the paper, since I could not find the abstract.
Bad news from the rangelands
1977 was an important year for conservation in Kenya for it was then that
sport hunting and all other consumptive uses of wildlife and attendant
value added activities were banned. It was also the year when the Kenya
Rangeland Ecological Monitoring Unit (KREMU) began to monitor the
numbers and distribution of livestock and wildlife throughout the 500,000
km2 of Kenya’s arid and semi-arid rangelands.
So, perhaps uniquely, a major change in conservation policy—a ban on
all consumptive utilisation of wildlife—coincided with a new capacity to
monitor its effect and impact.
The monitoring results have been deeply disturbing, and by the mid-
1990s a number of warnings were issued about a major decline in wildlife
right across Kenya’s rangelands, even in the most heavily used tourist
areas. The only good news was that loss rates seemed significantly less
inside the Protected Areas than outside where some 70% of all Kenya’s
wildlife are to be found. More recent analyses eliminate even this ray of
hope—rates of wildlife loss continue unchecked, and are now the same
both inside and outside the Protected Areas. Since 1977, Kenya has lost
60%–70% of all its large wildlife.
While losses of such magnitude indicate a major institutional failure to
protect wildlife, the pernicious spread of agriculture throughout the rangelands,
even around important conservation and tourism areas like the Mara
area of Narok and the Amboseli area in Kajiado, give clear signals of a policy
failure. Indeed, the entire economic system of rangeland production in
Kenya has undergone a radical transformation since the mid-1970s
(Figure 2): the human population is growing at >3% per annum; cultivation
is growing at >8% per annum; while livestock numbers remain stable,
offtake is growing at >4% per annum; and wildlife is decreasing by >3%
per annum.
From the perspective of the individual pastoral landowner, at the
macro-economic scale domestic and international markets are expanding
and there are real gains in producer prices. At the micro-economic scale,
the pastoral landowner sees improved market and transport networks,
improved market information networks (mobile telephone coverage is
expanding across the rangelands), improved access to financial services,
ever-increasing opportunities for off-farm jobs and investment,1 and a
wider availability and choice of goods and services.
6. Western D, Russell S, Cuthill I (2009). PLoS ONE 4(7): e6140. doi:10.1371/journal.pone.0006140. The Status of Wildlife in Protected Areas Compared to Non-Protected Areas of Kenya.
Abstract
We compile over 270 wildlife counts of Kenya's wildlife populations conducted over the last 30 years to compare trends in national parks and reserves with adjacent ecosystems and country-wide trends. The study shows the importance of discriminating human-induced changes from natural population oscillations related to rainfall and ecological factors. National park and reserve populations have declined sharply over the last 30 years, at a rate similar to non-protected areas and country-wide trends. The protected area losses reflect in part their poor coverage of seasonal ungulate migrations. The losses vary among parks. The largest parks, Tsavo East, Tsavo West and Meru, account for a disproportionate share of the losses due to habitat change and the difficulty of protecting large remote parks. The losses in Kenya's parks add to growing evidence for wildlife declines inside as well as outside African parks. The losses point to the need to quantify the performance of conservation policies and promote integrated landscape practices that combine parks with private and community-based measures.
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