Hello, marmam community, I am pleased to share our new contribution, titled "Assessment of a non-invasive approach to pregnancy diagnosis in gray whales through drone-based photogrammetry and faecal hormone analysis." In this study, using data from the Pacific Coast Feeding Group gray whales, we assess the efficacy of a fecal progesterone immunoassay and drone-based photogrammetry for pregnancy diagnosis. We estimate the probability of pregnancy by analyzing fecal progesterone metabolites and body morphology through normal mixture models. Progesterone levels exhibited high variability, hindering accurate diagnosis. However, body width standardized by the total length at 50% of the total body successfully distinguished pregnant from nonpregnant females with high accuracy. Applying this method to whales of unknown pregnancy status revealed eight additional pregnancies, highlighting the potential of drone-based photogrammetry for reproductive rate assessments. *You can access this contribution here:* https://royalsocietypublishing.org/doi/10.1098/rsos.230452. *Cite this article:* Fernandez Ajó A., Pirotta E., Bierlich K. C., Hildebrand L., Bird C. N., Hunt K. E., Buck C. L., New L., Dillon D. and Torres L. G. 2023 Assessment of a non-invasive approach to pregnancy diagnosis in gray whales through drone-based photogrammetry and faecal hormone analysis R. Soc. open sci.10230452230452. http://doi.org/10.1098/rsos.230452 *Abstract*: Knowledge of baleen whales' reproductive physiology is limited and requires long-term individual-based studies and innovative tools. We used 6 years of individual-level data on the Pacific Coast Feeding Group gray whales to evaluate the utility of faecal progesterone immunoassays and drone-based photogrammetry for pregnancy diagnosis. We explored the variability in faecal progesterone metabolites and body morphology relative to observed reproductive status and estimated the pregnancy probability for mature females of unknown reproductive status using normal mixture models. Individual females had higher faecal progesterone concentrations when pregnant than when presumed non-pregnant. Yet, at the population level, high overlap and variability in progesterone metabolite concentrations occurred between pregnant and non-pregnant groups, limiting this metric for accurate pregnancy diagnosis in gray whales. Alternatively, body width at 50% of the total body length (W50) correctly discriminated pregnant from non-pregnant females at individual and population levels, with high accuracy. Application of the model using W50 metric to mature females of unknown pregnancy status identified eight additional pregnancies with high confidence. Our findings highlight the utility of drone-based photogrammetry to non-invasively diagnose pregnancy in this group of gray whales, and the potential for improved data on reproductive rates for population management of baleen whales generally. Thanks for sharing, *Alejandro Fernandez Ajó**,** PhD * *Postdoctoral Scholar* *Geospatial Ecology of Marine Megafauna (GEMM <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmmi.oregonstate.edu%2Fgemm-lab&data=05%7C01%7Calejandro.fernandezajo%40oregonstate.edu%7C9bc3cca8fd3d42b260aa08da809a489c%7Cce6d05e13c5e4d6287a84c4a2713c113%7C0%7C0%7C637963697376854523%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=UBQEQV7v6pyq%2FopIxpVKZmnxPnVrZev9uB6cfyiL72I%3D&reserved=0>) Lab * Marine Mammal Institute | *Dept. of Fisheries, Wildlife, & **Conservation Sciences* *Oregon State University* *Pronouns: he, him, his* *fernaale**@**oregonstate.edu* <kevin.bierlich@oregonstate.edu>