Dear colleagues, My co-authors and I are happy to announce the publication of the following paper in the Journal of Experimental Biology: Christiansen, F., Sironi, M., Lewin, N., Marón, C.F. & Uhart, M.M. 2026. Influence of water temperature, body size, condition, and gull-inflicted lesions on heat loss in southern right whales in Península Valdés, Argentina. Journal of Experimental Biology 229: jeb250925. Abstract: Southern right whales (Eubalaena australis; SRWs) are well adapted to cold waters because of their large body size and thick blubber. Each year, they migrate from high-latitude feeding grounds to warmer breeding grounds where they give birth. To assess thermal benefits of this migration, we modelled the effects of body size, condition and water temperature on heat loss. Using unmanned aerial vehicle photogrammetry at the Península Valdés calving ground in Argentina, we measured body length, volume, condition and surface area of living SRWs. Blubber thickness was predicted from a blubber-mass model and validated using necropsy/catch data. Sensible heat loss was estimated using a model incorporating blubber thermal conductivity and body temperature, whereas respiratory heat loss was based on respiration rate and tidal volume models. We compared heat loss in Península Valdés with that in South Georgia/Georgia del Sur (SG/GS), a key feeding ground. Body size had a strong positive effect on both heat loss values, but mass-specific loss decreased as surface-area-to-volume ratio declined. Increased body condition reduced sensible heat loss. Migration from SG/GS to Península Valdés reduced calf heat loss by 26% during early lactation. However, total heat loss remained low relative to field metabolic rate (FMR), indicating limited thermoenergetic benefit from migration. Only at poor body condition (<−0.35) did heat loss exceed FMR, threatening survival. Notably, gull-inflicted lesions significantly increased heat loss in small and poorly conditioned calves, but had no effect on larger or better-conditioned calves. These findings highlight body condition as a key regulator of heat loss in baleen whales. The paper is available at the following link: https://journals.biologists.com/jeb/article/229/1/jeb250925/370316/Influence... Best regards, Fredrik Christiansen Senior Researcher Marine Mammal Research, Department of Ecoscience, Aarhus University Frederiksborgvej 399, 4000 Roskilde, Denmark f.christiansen@ecos.au.dk<mailto:f.christiansen@ecos.au.dk> http://scholar.google.com.au/citations?user=vkA5Y3EAAAAJ&hl=en&oi=sra http://www.researchgate.net/profile/Fredrik_Christiansen3/?ev=hdr_xprf