KAZA elephants – new analysis adds vital details

A technical review of a recent census of elephant populations in southern Africa provides thought-provoking details behind the broader figures. Detailed analysis of population and carcass trends by country and region reveals the impact of poaching and trophy hunting on elephants. This granular information allows us to understand the human impacts on elephants better and empowers conservationists to make informed decisions.

[Editorial note: Useful definitions and explanations for some of the terms used can be found at the end of the article.]

At the end of 2023, the Kavango-Zambezi (KAZA) Transfrontier Conservation Area 2022 KAZA Elephant Survey results, revealing an estimated population of 227,900 savannah elephants. The magnitude of such an endeavour cannot be underestimated: KAZA covers a 520,000km² network of landscapes across five different countries (Angola, Botswana, Namibia, Zambia, and Zimbabwe), and to count its elephants is an undeniably impressive feat. The results suggest with cautious optimism that the world’s largest population of savannah elephants remains stable.

Yet the problem with viewing this massive region through a wide-angle metapopulation lens is that vital country- and regional-level nuances are lost. Some of these missing details have essential ramifications for guiding management and conservation policies. In the space of a few months since the release of the survey report, non-governmental organisation Elephants without Borders (EWB) has produced their technical review of the results. They offer a more granular analysis of elephant population trends and compare the data with those of previous surveys to provide comprehensive context.

Some of the important questions they set out to answer included:

How and where are populations changing within countries?
Are large elephant populations in Zimbabwe and Botswana still growing?
How are elephant populations faring where hunting is occurring?
Is poaching affecting elephant populations in KAZA?

Their 36-page report, which uses more localised data to focus on trends and changes, offers detailed answers to some of these questions and more. We have summarised the more critical aspects of their findings below.

Northern Botswana’s elephants

As expected, the 2022 KAZA Elephant Survey revealed Botswana to be home to most of the KAZA elephant population (58%). In addition to this fact, there are several reasons why this region is of particular interest to policymakers and conservationists. One particularly sensitive aspect is the lifting of the elephant trophy hunting moratorium in 2019, often defended by the rhetoric of a rapidly expanding elephant population. Another is growing evidence of increased poaching activity.

According to the EWB analysis, overall elephant populations in northern Botswana have changed little between 2010 and 2022 (in direct contradiction to several government statements). At most, the report indicates a maximum growth rate of 2% per year between 2010 and 2022 and emphasises that “elephant numbers are no longer proliferating in Botswana”.

However, there are notable differences in the population trends across the different landscapes. Elephant numbers within Moremi Game Reserve, Chobe National Park, the Okavango Delta, and surrounding ecotourism regions remained either stable or increased between 2018 and 2022. Outside of these protected areas, many forest reserves, farming areas, and hunting blocks have shown negative population trends.

The authors of the EWB report also spent time separately analysing trends within the Okavango Panhandle populations. They explain their specific focus on this region as it is home to “controversial” elephant populations, plagued by perceptions of burgeoning populations and increased human-wildlife conflict. The report concludes that, once again, contrary to public government statements, elephant numbers have remained roughly stable in the Panhandle since 2010. Comparison with more recent surveys revealed an 18% decline in overall elephant numbers since 2018.

Mortalities and poaching

All carcass ratios in northern Botswana increased substantially between 2014 and 2022 (from 8.2 % to 12.4%). To put this into context, 8% is generally considered by ecologists and statisticians to be the cut-off for a growing or stable population. If the ratio is higher, mortalities likely outweigh births, resulting in a decreasing population. 63% of Botswana’s elephant population occupies regions with a greater carcass ratio than 8%. Once again, this was not a homogenous change seen across all of the areas surveyed: carcass ratios in Moremi Game Reserve, Chobe National Park, the Okavango Delta, and surrounding ecotourism regions remained either unchanged or decreased. The most significant increases were seen in the southeastern part of the study area, where elephant populations were also noted to have declined.

Equally concerningly, of all the regions surveyed in 2022, Botswana’s fresh/recent carcass ratio (mortalities within 12 months of the survey) was also the highest (0.70%) in KAZA. During EWB’s 2018 study, researchers identified several poaching “hotspots”, including parts of the Okavango Panhandle and the Khwai area. Encouragingly, fresh/recent carcass ratios were lower in these regions. However, they were raised at the border with Namibia near the Kwando and Chobe Rivers and the Savute region of Chobe. According to the 2022 KAZA Elephant Survey report, these carcasses were examined and found to have their tusks intact. However, EWB reports conducting reconnaissance flights in 2023 and 2024 (after the 2022 survey flights) and locating 56 poached elephants. Most of these were found in NG15 and NG18 (the Linyanti region just west of Chobe National Park).

This documentation of poached elephants was done over a small area, and numbers may also be high in areas not assessed, with the study noting that “this small sample is not sufficient for estimating poaching rates in an area of over 500,000 km2. More monitoring of poaching is badly needed in KAZA.”

Hunting

During their analysis, EWB compared elephant population trends in areas with and without trophy hunting to understand how hunting might affect elephant dynamics or vice versa. They found that between 2018 and 2022, the elephant numbers, on average, increased in areas without hunting and decreased significantly in those with hunting. The same pattern was observed for breeding herds and bulls, though the changes across the intervening four years were insignificant for bulls. These changes do not suggest that trophy hunting is causing an overall population decline but rather that elephants are moving from hunting to non-hunting areas (which, it should be noted, could cause complications if elephants move to areas with higher human populations – exacerbating human-elephant conflict).

The cause for these shifts remains unknown, though the authors suggest that elephants may be shifting to avoid the disturbance caused by trophy hunting. They also highlight that if these movements are a consequence of trophy hunting, they may undermine the initial reasons for reinstation and call into question its sustainability as a practice.

Angola

Though Angola and Zambia combined are home to just 4% of KAZA’s elephants, the former has gained considerable interest as a potential elephant habitat since the end of the Angolan Civil War in the early 2000s. So much so that it has even been suggested that Botswana could translocate “excess” elephants to the region. The 2022 KAZA survey reported an elephant population growth of 80% between 2015 and 2022. However, a major qualifier is attached to this statistic: the count was likely substantially skewed by a few anomalously large herds counted near the Kwando River. The authors of the EWB analysis state outright that it is implausible that Angola’s elephant population has increased to such an extent.

This interpretation is supported by the previous 2015 census, which recorded fresh/recent carcass ratios of 10% – one of the highest such ratios ever recorded in savannah elephants and one highly likely to be associated with a declining population. Between 2015 and 2022, elephants have all but vanished from the western part of the Angolan region of KAZA, and the authors recorded a 98% decline in populations along the Cuito and Kavango Rivers.

Interpreted in combination, these signs all point towards an “elephant population in trouble”. Worryingly, the EWB analysis describes Angola as an attractive population sink for elephants, meaning that elephants may move into Angola from areas of high elephant density in Botswana and Namibia but then struggle against extrinsic factors such as high levels of poaching and even landmines left behind from the years of civil war. Over time, these population sinks have the potential to contribute to broader population declines.

Zimbabwe

The 2022 KAZA Elephant Survey and subsequent EWB analysis point to largely positive news regarding Zimbabwe’s elephant populations. Populations in northwest Matabeleland and Sebungwe have remained stable (and even increased). Similarly, Hwange National Park’s numbers have remained largely stable, though there has been some internal shifting within the park (which the authors suggest could be linked to new artificial waterholes). Moreover, all-carcass and fresh/recent-carcass ratios decreased to some degree, suggesting the possibility of reduced poaching pressure in Zimbabwe.

Namibia

The EWB analysis notes that elephant numbers generally decreased along Namibia’s border with Angola (while being stable along the Botswana border).

Zambia

Due to differences in counting techniques (see below), EWB was relatively limited in its ability to formally compare the current survey to those conducted previously in Zambia and thus was unable to determine trends accurately.

However, the 2022 survey reports a worrying decline in estimated elephant populations in the Kafue region from 6,688 in 2015 to 3,840 in 2022. Even with wide confidence margins, this population reduction is concerning, and EWB authors suggest that further surveys in the Kafue are warranted.

The power (and limitations) of surveys of elephants

“The 228,000 elephants estimated to occur in KAZA seems large. However, determining the health of KAZA’s elephant population requires interpreting that number in light of how it has changed from earlier estimates.” In this respect, the EWB is somewhat critical of the report from the 2022 survey, which did not include any formal trend analysis. They emphasise that the primary goal of any census should not be the count itself but rather trends over time.

One of the primary challenges faced by EWB in compiling their analysis was that the modified methodology of the 2022 survey made comparisons with surveys of previous years more challenging. In particular, stratum boundaries were changed from preceding surveys, making it difficult to compare results and investigate trends. In some instances, EWB overcame these differences by reformulating previous data to match the new methodology as closely as possible. However, the strata for Zambia were so changed that any simple comparisons between years were impossible.

The authors suggest that even when a survey is conducted without the intention of detailed trend analysis, it should still be structured to facilitate the process. They conclude that the best way to do this is to keep the stratum boundaries consistent, or if change is necessary, such changes should be made “with a nod towards facilitating comparison.” It is unclear why the strata for the 2022 survey were altered.

Final thoughts on KAZA’s elephants

The Kavango-Zambezi (KAZA) Transfrontier Conservation Area is conservation on a grand scale – designed to promote resilient habitats and animal populations. Population overviews such as the one provided by the 2022 survey are undeniably important, especially for a species as impactful as elephants. It is deeply encouraging that the overall numbers of elephants are stable.

However, detailed analysis allows for detecting nascent threats before they have disastrous effects on a population. As the authors of the EWB report conclude, “managers need accurate and detailed information about how and where elephant populations are changing to effectively manage KAZA’s 227,900 elephants”.

Definitions

Carcass ratios: a technique used by ecologists to put mortalities into context and determine whether a population is likely to be growing, declining or stable.
All-carcass ratios: carcass estimates as a percentage of live elephant and carcass estimates. Previous ecological studies have shown that a ratio of over 8% is generally the cut-off for a stable population. If the ratio goes any higher, the mortality rate outstrips the birth rate, and the population begins to decline.
Fresh/recent carcass rations: carcasses deemed to be less than 12 months old as a percentage of live elephant and carcass estimates. This ratio can be used to detect emergent population challenges such as poaching surges and disease events.
Strata/stratum boundaries/stratification: when conducting an aerial survey, the region of interest is divided into strata (that is, it is stratified), and the sizes and shapes of these strata are determined by environmental conditions such as permanent water availability, vegetation type and landscape use. These, in turn, determine the spacing of the transects flown by the aerial counting team. So, for example, a section of riverine habitat surrounded by lush flood plains will likely support a higher density of animals and thus requires that the counting team flies narrow transects to estimate the number of animals present accurately. Conversely, pilots can fly much wider transects in a sparse area without drinking water and little vegetation because there are fewer animals to count, so the risk of underestimating populations is reduced.

Reference

Schlossberg, S. and Chase, M. (2024) ‘Population trends and conservation status of elephants in Botswana and the Kavango Zambezi Transfrontier Conservation Area: A review of elephant aerial surveys, 2010 – 2022’, An Elephants Without Borders Technical Report

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