A country can gain giraffes while remaining vulnerable to losing them. More animals improve the numerical picture, but the location of those animals determines how much damage one local crisis could cause.
That distinction drove a 2019 assessment of Uganda's giraffes by Michael B. Brown, Douglas T. Bolger and Julian Fennessy. The researchers combined a reconstruction of historical distribution with modern photographic surveys. They found a substantial recovery from the extremely low estimates reported in the early 1990s, accompanied by a striking concentration: more than 90% of the country's estimated adult and subadult giraffes lived in the part of Murchison Falls National Park north of the Nile.
The finding changed the question that a national total alone could answer. Uganda had many more giraffes than at its recorded low point. It also depended heavily on the continued security of one population.
A map assembled from unequal records
Reconstructing an animal's former range is different from surveying its present population. Brown and colleagues assembled 76 distinct sources, including scientific studies, historical accounts, government records and unpublished reports. These did not constitute a single monitoring programme. Observers worked in different places, used different methods and recorded information for different purposes.
Some accounts established that giraffes had occurred in an area without providing a dependable count. Others offered estimates for protected areas, often from aerial surveys. Even the older national estimates varied considerably. The authors therefore had to reconstruct broad changes from evidence that was uneven in both time and quality.
Their historical picture showed a wider Ugandan distribution, followed by the disappearance of several populations. The national collapse was especially severe during the decades of civil unrest. Reports from the early 1990s placed Murchison Falls at 78 giraffes and Kidepo Valley at three. These figures are historical estimates from their respective surveys, not the result of a modern countrywide photographic census.
Historical reconstruction also has a cultural limit. The sources available to the researchers did not fully incorporate indigenous knowledge. The resulting map records what the assembled documents could establish; it should not be mistaken for a complete account of every place giraffes once inhabited.
The distinction matters when looking at a smooth historical graph. The paper grouped estimates by decade and interpolated across gaps. A line joining two decades is a visual reconstruction between observations, not evidence that animals were counted every year or declined at a steady rate.
Turning today's photographs into population estimates
The modern component used a different kind of evidence: individual identities.
Researchers photographed giraffes and matched their coat patterns between encounters. A giraffe seen on several survey occasions remained one animal in the catalogue. Its repeated appearances also supplied information about the chance of finding a living giraffe during a survey.
In northern Murchison Falls, the methods describe surveys from December 2014 to July 2017. The researchers recorded 6,231 encounters and identified 1,556 different adult and subadult giraffes across the study. Those two numbers answer different questions. Encounters describe the observation effort; the catalogue describes how many individuals appeared at some point during the monitoring period.
Neither is automatically the number alive on the final survey date. Some giraffes could have died, entered the counted age classes or been moved during the study. Others could have remained alive but gone unseen on a particular occasion.
The analysis used repeated sighting histories to estimate detection probability, then adjusted observed numbers for animals likely to have been missed. Its July 2017 estimate was 1,318 adult and subadult giraffes, with a reported standard error of 27.6.
Calves were excluded from this particular abundance analysis. Their survival and observation patterns required additional treatment. The resulting estimate should therefore be described by its age coverage, rather than casually converted into an all-age population total.
Recovery in numbers, contraction in distribution
Combining the contemporary assessments produced a national estimate of roughly 1,400 adult and subadult giraffes. Most belonged to the northern Murchison Falls population. Kidepo remained much smaller, while translocations had begun establishing giraffes in additional areas.
That distribution contrasted with the historical reconstruction. Uganda had formerly supported several populations, without a single one containing such an overwhelming share of the national total.
A concentration of this kind creates a dependency. If a major threat affects the principal population, there are relatively few animals elsewhere to buffer the national loss. Establishing additional populations can reduce that dependency, provided the new sites support survival and reproduction.
The paper discussed development pressure and other threats in the context of conditions known when it was written. Those passages should not be read as a current assessment of particular projects. The durable result is the demographic and geographic relationship: an improving total can coexist with exposure concentrated in one place.
The historical evidence supports a strong association between Uganda's political upheaval, reported killing of wildlife and population collapse. It does not isolate the effect of each cause experimentally. Likewise, subsequent recovery occurred alongside improved stability and conservation effort, but the study could not calculate how many giraffes each intervention saved.
Why additional populations need their own evidence
Moving animals changes a map immediately. Creating another population that can persist takes longer.
The 2019 assessment provided a reason to spread the national population more widely. It did not itself establish that every recipient site would become self-sustaining. A group of released giraffes might survive without reproducing, or produce calves that rarely reach maturity. Its long-term contribution depends on those later outcomes.
A subsequent primary study published in 2025 followed Uganda's donor and recipient populations through the establishment phase. It documented growth after the introduction of giraffes to new sites and, at Lake Mburo, the appearance of a second locally born generation. That later evidence addresses a question the historical reconstruction could only raise: whether geographic diversification was producing breeding populations.
The two studies should remain separate in a numerical comparison. Their surveys cover different years, and some abundance analyses include different age classes. Comparing the 2019 adult-and-subadult estimate directly with a later all-age estimate would mix population change with a change in what was counted.
Nor does the existence of more populations eliminate every shared threat. Several sites can remain exposed to the same national policies, regional climate pressures or limitations in conservation funding. Geographic diversification can reduce dependence on one locality without making the whole system independent of common risks.
What the national total could not show
The study's main contribution was to place abundance inside a longer history of occupancy and loss.
A national count asks how many animals remain. A distributional assessment asks where they remain, how many separate populations carry that total and which former populations have disappeared. Repeated individual monitoring then asks whether those surviving or restored populations are replacing themselves.
Uganda's record showed why all three questions matter. The numerical recovery was substantial. Its concentration in northern Murchison Falls was also substantial. Recognising both made it possible to describe recovery more accurately and to identify the evidence needed from future translocations.
The next secure population would have to become more than another point on a map. It would need its own continuing record of survival, births and recruitment.
Sources
Michael B. Brown, Douglas T. Bolger and Julian Fennessy (2019). All the eggs in one basket: A countrywide assessment of current and historical giraffe population distribution in Uganda. Global Ecology and Conservation, 19, e00612.
Michael Butler Brown, Herbert Kasozi, Robert Aruho, Stephanie Fennessy, Sara Ferguson, Arthur Muneza and Julian Fennessy (2025). Assessing the success of conservation translocation establishment: Post-translocation demography of Nubian giraffe (Giraffa camelopardalis camelopardalis) in Uganda. Conservation Science and Practice, 7, e70127.
