Goudalier C. auteur aut IRD Mouillot D. auteur aut IRD Bernagou L. auteur aut IRD Boksmati T. auteur aut IRD Bristol C. auteur aut IRD Clark H. auteur aut IRD Herandarudewi S. M. C. auteur aut IRD Hocdé Régis auteur aut IRD Koester A. auteur aut IRD McIvor A. J. auteur aut IRD Nair D. auteur aut IRD Nandika M. R. auteur aut IRD Ponnampalam L. auteur aut IRD Sahri A. auteur aut IRD Trotzuk E. auteur aut IRD Zaaba N. A. auteur aut IRD Mannocci Laura auteur aut IRD text journalArticle eng text/pdf reformatted digital access The monitoring of body condition, reflecting the state of individuals' energetic reserves, can provide early warning signals of population decline, facilitating prompt conservation actions. However, environmental and anthropogenic drivers of body condition are poorly known for rare and elusive marine mammal species over their entire ranges. We assessed the global patterns and drivers of body condition for the endangered dugong (Dugong dugon) across its Indo-Pacific range. To do so, we applied the body condition index (BCI) developed for the related manatee based on the ratio of umbilical girth (approximated as maximum width times pi), to straight body length measured in drone images. To cover the entire dugong's range, we took advantage of drone footage published on social media. Combined with footage from scientific surveys, social media footage provided body condition estimates for 272 individual dugongs across 18 countries. Despite small sample sizes relative to local population sizes, we found that dugong BCI was better, that is, individuals were 'plumper', in New Caledonia, the United Arab Emirates, Australia and Qatar where populations are the largest globally. Dugong BCI was comparatively poorer in countries hosting very small dugong populations such as Mozambique, suggesting a link between body condition and population size. Using statistical models, we then investigated potential environmental and anthropogenic drivers of dugong BCI, while controlling for seasonal and individual effects. The BCI decreased with human gravity, a variable integrating human pressures on tropical reefs, but increased with GDP per capita, indicating that economic wealth positively affects dugong energetic state. The BCI also showed a dome-shaped relationship with marine protected area coverage, suggesting that extensive spatial protection is not sufficient to maintain dugongs in good state. Our study provides the first assessment of dugong body condition through drone photogrammetry, underlining the value of this non-invasive, fast and low-cost approach for monitoring elusive marine mammals. specialized aerial surveys conservation drones photogrammetry population monitoring sirenians OCEAN INDIEN PACIFIQUE 034 126 082 [Early access] [18 ] 2025 https://www.documentation.ird.fr/hor/fdi:010094259 10.1002/rse2.70016 [F B010094259] https://www.documentation.ird.fr/hor/fdi:010094259 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2025-07/010094259.pdf IRD - Base Horizon / Pleins textes 2025-07-15 2025-11-04 fdi:010094259 fre