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., Sprogis, K.R., Nielsen, M.L.K., Glarou, M. & Bejder, L. 2023. Energy expenditure of southern right whales varies with body size, reproductive state and activity level. Journal of Experimental Biology 226: jeb245137. doi: 10.1242/jeb.245137. Abstract: Quantifying the energy expenditure of animals is critical to understanding the cost of anthropogenic disturbance relative to their overall energy requirements. We used novel drone focal follows (776 follows, 185 individuals) and aerial photogrammetry (5372 measurements, 791 individuals) to measure the respiration rate and body condition loss of southern right whales (Eubalaena australis) on a breeding ground in Australia. Respiration rates were converted to oxygen consumption rate and field metabolic rate (FMR) using published bioenergetic models. The intra-seasonal loss in body condition of different reproductive classes (calves, juveniles, adults, pregnant and lactating females) was converted to blubber energy loss and total energy expenditure (TEE). Using these two metrics, we tested the effects of body size, reproductive state and activity level on right whale energy expenditure. Respiration rates and mass-specific FMR decreased exponentially with an increase in body size, as expected based on allometric scaling. FMR increased curvilinearly with an increase in swim speed, probably as a result of increased drag and increased locomotion costs. Respiration rates and FMR were 44% higher for pregnant and lactating females compared with those of adults, suggesting significant costs of fetal maintenance and milk production, respectively. The estimated FMR of adults based on their respiration rates corresponded well with the estimated TEE based on body condition loss. The rate of decline in body condition of pregnant and lactating females was considerably higher than expected based on respiration rates, which probably reflects the milk energy transfer from mothers to calves, which is not reflected in their FMR. The paper can be accessed from the following link: https://journals.biologists.com/jeb/article-abstract/226/13/jeb245137/322683... Also, check out the pedunculate oak tree that was planted by JEB for this article: https://forest.biologists.com/landscape/?id=84372 What a great initiative! 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