Surveys


Why do aerial surveys?

Elephants and wildlife are often in remote and difficult terrain and the best way to count them is from the air. Aerial surveys provide vital information on their status, seasonal distribution and abundance. They improve our understanding of wildlife populations, which allows us to base our conservation action on solid scientific understanding and guide future research and monitoring, with an emphasis on evaluating the effectiveness of management policies.

EWB has conducted extensive aerial surveys to help determine elephant and wildlife numbers, their habitat needs and seasonal distribution. Since 2001, the EWB team has amassed over 4000 hours of aerial survey flying, counting wildlife in Angola, Botswana, Namibia and Zambia. EWB is meticulous and rigorous in conducting the most comprehensive aerial surveys, which are providing new and essential information on the population status of elephants and other threatened wildlife species.

Chobe Forest Reserves Surveys

EWB flew consecutive seasonal surveys during both the wet and dry seasons between 2011 and 2013 over the Chobe District, a survey area of about 22560 km2 in extent, which included Chobe National Park (NP), Chobe Forest Reserve (FR), Kasane FR and Extension, Kazuma FR, Sibuyu FR and Maikaelelo FR, and surrounding Wildlife Management Areas.
Results revealed herbivore populations in the District appear to be stable. However, the extent of bush fires across large areas of the District, a major determinant in the health of the ecosystem, are concerning. Also, the level of deforestation and encroaching human activities for arable fields along the Northern Plains ecotone and Chobe FR ridge, which both fall within important wildlife corridors are destructive, and will impede wildlife movements and should be conserved. The allocation of arable fields in the middle of identified elephant pathways is hindering wildlife access to water, which will lead to an inevitable increase in human elephant conflict. While there is considerable development taking place within the District, EWB is determined to continually assist local, district and central government authorities to provide them with scientific data to ensure a positive relationship between people and wildlife co-existing in the region.

2010 Northern Botswana Survey

During the 2010 dry season, a fixed-wing aerial survey of elephants and wildlife was flown over the core wildlife conservation areas of northern Botswana. The aerial survey took nearly 250 hours of flying time, a flight line total of 25,598 km, covering a total of 73,478 km2, which included the National Parks of Chobe, Makgadikgadi, Nxai Pan, Moremi Game Reserve, the Okavango Delta and the surrounding Wildlife Management Areas in the Ngamiland, Chobe and Central districts. Technically robust, the survey’s sampling intensity averaged 20% in comparison to 5% during previous surveys and is the first independent fixed-wing aerial survey to provide concession level estimates for wildlife populations in Botswana.

Between 1993 and 2004, the Botswana government had conducted eight systematic aerial surveys. EWB’s 2010 data allowed for a comparative analysis of wildlife distribution, abundance and trends over time. However, some of the results were unexpected and revealed that in 17 years, the populations of 11 animal species in the Okavango Delta specifically had plummeted by an average of 61 per cent, while elephant numbers across northern Botswana appeared to have stabilized, and in the Chobe district where the highest density of elephants occur, the majority of wildlife populations remained fairly stable or were increasing. These findings raised much concern, awareness, and some scepticism, however also stimulated action, on many levels, to ensure a better understanding of the drivers causing downward trends.

This study also verified the importance of continual monitoring and that conservation management requires a solid understanding of wildlife population dynamics and reliable estimates of population densities, while further research is required to ensure a healthy ecosystem.

Kavango-Zambezi Transfrontier Area (KAZA TFCA) Surveys

In January 2003, at the end of almost 30 years of civil conflict in Angola, EWB flew the first systematic aerial survey, ever, to estimate elephant and wildlife numbers in southeast Angola. The survey area, Luiana Partial Reserve, was severely affected by the civil war. It is reported that 100,000 elephant were slaughtered for their ivory and meat to help fund the war. In this area, which was left with virtually no wildlife, EWB, together with Conservation International, was the first organization to record wildlife population returning to southeast Angola. EWB expanded their surveys to encompass the neighbouring protected area, Sioma Ngwezi National Park, in southwest Zambia, (the last estimates for elephants in this remote park were taken in 1969), and Namibia’s Caprivi Strip. These surveys provided the first comprehensive regional assessment on the status of elephant populations. Subsequently, aerial surveys were conducted each year, over 3 years, which provided data to undertake comparative analyses.

EWB’s data from these aerial surveys revealed that elephants were returning in growing numbers to southeast Angola. The 2005 survey data of the Caprivi Strip, suggests that elephant numbers increased by only 15%, since 1998, which, is considered a relatively small population increase over such a timeframe. However, in Sioma Ngwezi, elephant numbers appeared to have decreased from 1,212 in 2003 to 385 in 2005. In contrast, the three aerial surveys of Luiana Partial Reserve in southeast Angola indicated that elephant numbers were increasing rapidly and expanding their range, from 329 in January 2004, to 1827 in November 2005, to an estimate of 8000 in 2007. The end of the war in Angola appears to be providing the requisite security for elephants to return to their ancestral homeland.

Okavango Panhandle Surveys

The Okavango Panhandle is considered a high human-elephant conflict (HEC) area in Botswana. In this troublesome conflict zone, elephants are trapped by the Caprivi border fence and northern buffalo fence. The impenetrable floodplains of the Okavango River restrict elephants moving west out of the region. Within this 8500sq km area, the only permanent water is in the Okavango River, where many settlements are located. During the dry season, elephant herds run a daily gauntlet through settlements to reach water in the Okavango River. How many elephant are trapped in this region? What is the population growth rate? What management options are there to help relieve this compression? To help answer these pertinent questions EWB collaborated with Anna Songhurst, a PhD student from the University of Botswana and Imperial College, London, studying HEC. Together we flew 2 aerial surveys. The first survey, conducted in August 2008, yielded an estimate of 9000 elephants trapped in the Okavango triangle. In July 2010, the second survey was conducted and the survey results estimated a staggering 14,000 elephants. ?EWB suggests that corridors be created to allow elephant to move out of this region. Corridors must be created along wildlife migration paths that meet up with the fence. Creating small gaps or openings in the fence will allow elephants to move into the Caprivi and Angola where elephant densities are low and relieve HEC along the Okavango River.

Aerial surveys

Northern Botswana
Status of Wildlife Populations and Land Degradation in Botswana’s Forest Reserves and Chobe District, April 2013
Download PDF (10.4 MB)

Northern Botswana
Dry Season Fixed-wing Aerial Survey of Elephants and Wildlife in Northern Botswana September-November 2010, June 2011
Download PDF (12.8 MB)

Okavango Delta, NG26, Botswana
Fixed-wing Aerial Survey of Wildlife in the Abu Wildlife Management Area. October 2010
Download PDF (6.3 MB)

Okavango Panhandle, NG11, NG12 and NG13
Elephant Survey July 2010, Eastern Okavango Panhandle, Botswana.
Download PDF (631 KB)

Chitabe Concession in Botswana, Okavango Delta.
Fixed-wing aerial census of Wildlife in the Chitabe Concession in Botswana September 2010.
Report not available

Chitabe Concession in Botswana, Okavango Delta.
Fixed-wing aerial census of Wildlife in the Chitabe Concession in Botswana August 2009.
Report not available

Namibia Nature Foundation, report produced:
Aerial Wildlife Census of the Caprivi River Systems, a survey of Rivers, Wetlands and Floodplains. September 2009.
Download PDF (5.5 MB)

Okavango Panhandle, NG11, NG12 and NG13
Elephant Survey, Eastern Okavango Panhandle, Botswana (NG11, NG12 and NG13),
Chase, M., Songhurst, A., August 2008
Download PDF
(298 kb)

Namibia Nature Foundation, report produced:
Aerial Wildlife Census of the Caprivi River Systems, a survey of rivers, wetlands and floodplains,
Chase, M., 2007,
Download PDF
(4.3 mb)

Namibia Nature Foundation, report produced:
Status of Wattled Cranes on the floodplains of north-east Namibia: results from an aerial survey during September 2007
, Brown, C., Chase, M., Nkala, T., Landen, K., Aust, P.
Download PDF
(286 kb)

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