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Aerial surveys point to a long decline in common duikers in Gonarezhou

Female common duiker jumping across a sandy track in Maputo National Park, Mozambique
Conservation · Population & status

A new analysis of more than three decades of wildlife surveys in Gonarezhou National Park, Zimbabwe, points to a marked local decline in common duikers (Sylvicapra grimmia). The study used repeated aerial counts originally designed to monitor elephants and other large herbivores, but the surveys also recorded smaller antelopes when they were seen.

Common duiker trend fell by an estimated 10.7% per year

For common duikers, nine comparable surveys from 2007 to 2025 produced a downward trend equivalent to an estimated decline of about 10.7 percent per year. Steenbok showed a similar pattern, while several medium-sized herbivores also declined during the later part of the monitoring period. In contrast, the populations of some much larger herbivores, including buffalo, giraffe and zebra, did not show the same decline.

The researchers found that body size was one of the clearest differences between species that declined and those that remained stable or continued to increase. They suggest that smaller herbivores may have become more vulnerable to predators when food became less available. Changes in vegetation caused by high elephant densities could also have reduced browse and cover for small browsing antelopes such as duikers.

The authors stress that the causes of these population changes cannot be determined retrospectively from the survey series. They consider rainfall, predation and elephant-driven vegetation change and conclude that no single factor fully explains the observed trends; several may have acted together.

Aerial survey design limits interpretation for small antelopes

The aerial surveys were designed for elephants rather than small antelopes. For common duiker and steenbok, interpretation of the trend depends on the visibility bias remaining approximately constant through the survey programme. Under that assumption, the estimates show significant declines after 2007, while the body-size pattern across species suggests that predation likely played an important role.

Sources and image credit

  1. Dunham, K. M. (2026). Three decades of monitoring reveal that differing population trends of large herbivores in Gonarezhou National Park, Zimbabwe, are related to species body mass. Ecology and Evolution, 16(8), e74110. https://doi.org/10.1002/ece3.74110Primary peer-reviewed open-access study, first published 13 August 2026.

Image: Charles J. Sharp — female common duiker in Maputo National Park, Mozambique. Source: Wikimedia Commons. Representative image for this story; not presented as an animal or scene from the reported study or event. · CC BY-SA 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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