The movements of seabirds during the immature period generally remain poorly understood, primarily due to the challenges involved with tracking birds that do not regularly return to a nest. This knowledge gap prevents us from gaining a full understanding of the areas used by seabird populations. Here, we attempted to track the post-fledging movements of Atlantic Puffins Fratercula arctica from Skomer Island (Wales), by deploying geolocators on chicks ready to leave the nest. Despite our very small return rate (just two loggers out of 54, recording 485 and 196 days of data after fledging, respectively), our results provide a first glimpse into the distribution and scale of movements of young Puffins after fledging. The young Puffins undertook movements comparable in scale to those of post-breeding adults, and there were considerable differences between the two individuals. New initiatives to track juvenile seabirds in much larger numbers will hopefully soon provide more insight into seabird post-fledging movements.

Advances in tracking technology and the miniaturisation of devices since the early 2000s have transformed our understanding of seabirds' migratory and non-breeding movements, especially through the use of geolocation devices. Although gaps remain, we now have good basic knowledge of the non-breeding movements of many pelagic seabird orders across most oceans, from the very large albatrosses (Weimerskirch & Wilson 2000) to the smallest storm petrels (Militão et al. 2022). The largest of the remaining knowledge gaps concerns the non-breeding movements of juvenile and immature individuals. Due to their long breeding deferral, low survival (compared to adults) and lower site philopatry, using archival geolocators to track the movements of seabirds after they fledge is time-consuming and expensive, as many loggers need to be deployed in order to recover a few, several years later. For these reasons, logger deployments on fledglings have rarely been attempted. Nevertheless, a small number of successful attempts have provided useful insight into post-fledging or immature movements, for example in shearwaters (Campioni et al. 2020; Wynn et al. 2022). Satellite transmitters are an alternative option, and have been used successfully to track juveniles in a range of species (Wienecke et al. 2010; Yoda et al. 2017; Lane et al. 2021; Frankish et al. 2022), but they can be heavier and/or require deployment with a harness, which can be challenging for seabirds, especially pelagic species (Phillips et al. 2003).

Understanding the at-sea movements of young seabirds after fledging and until they start breeding is necessary to gain a full understanding of a species' use of different sea areas. Such knowledge is essential for effective seabird conservation, as differences in distribution and behaviour between young and adult birds can lead to differential exposure to threats (Roman et al. 2020; Weimerskirch et al. 2023). This is especially important because juvenile and immature individuals can make up a high proportion of a population and have a large influence on population dynamics (Sæther et al. 2013), including demographic responses to environmental change (Monaghan 2007; Fay et al. 2017).

Here, we report on the attempt to track the post-fledging movements of Atlantic Puffins Fratercula arctica (hereafter Puffins) from Skomer Island, Wales, which holds the largest Puffin colony in Wales of around 15,000 breeding pairs. Puffins are a migratory species with large interpopulation differences in non-breeding distribution (Fayet et al. 2017). On Skomer, the adults have a dispersive migration, with different birds employing different migration routes and destinations with high individual repeatability (Fayet et al. 2016). To test whether this dispersive pattern arises during early life, we attempted to track the movements of young birds in their first few years of life. Our small sample size does not allow us to answer this question, but nevertheless provides novel insight into the movements of juvenile Puffins after they leave their natal burrows.

We thank Dave Boyle, Jenny Roberts and Phillip Collins for their help in the field, and C. Taylor, B. Büche, E. Stubbings and the Wildlife Trust of South and West Wales for their support and for allowing us to carry out this study on Skomer. We thank Sarah Wanless and an anonymous reviewer for suggestions on how to improve this manuscript. At the time fieldwork took place, ALF was funded by scholarships from the Biotechnology and Biological Sciences Research Council grant ATGAAB9, Microsoft Research Cambridge, the British Council Entente Cordiale Scheme, and the Mary Griffiths Foundation. At the time of writing, ALF was supported by the Research Council of Norway, project no. 160022/F40 NINA basic funding. This work was funded by Microsoft Research Cambridge, the Department of Zoology of Oxford University, the Wilson Ornithological Society and the Welsh Ornithological Society.

Ashcroft, R. E. 1979. Survival rates and breeding biology of Puffins on Skomer Island, Wales. Ornis Scandinavica 10: 100–110. https://doi.org/10.2307/3676349

Campioni, L., Dias, M. P., Granadeiro, J. P. & Catry, P. 2020. An ontogenetic perspective on migratory strategy of a long-lived pelagic seabird: timings and destinations change progressively during maturation. Journal of Animal Ecology 89: 29–43. https://doi.org/10.1111/1365-2656.13044

Darby, J. H., Harris, M. P., Wanless, S., Quinn, J. L., Bråthen, V. S., Fayet, A. L., Clairbaux, M., Hart, T., Guilford, T., Freeman, R. & Jessopp, M. J. 2022. A new biologging approach reveals unique flightless molt strategies of Atlantic puffins. Ecology and Evolution 12: e9579. https://doi.org/10.1002/ece3.9579

Fay, R., Barbraud, C., Delord, K. & Weimerskirch, H. 2017. Contrasting effects of climate and population density over time and life stages in a long-lived seabird. Functional Ecology 31: 1275–1284. https://doi.org/10.1111/1365-2435.12831

Fayet, A. L., Freeman, R., Shoji, A., Boyle, D., Kirk, H. L., Dean, B. J., Perrins, C. M. & Guilford, T. 2016. Drivers and fitness consequences of dispersive migration in a pelagic seabird. Behavioral Ecology 27: 1061–1072. https://doi.org/10.1093/beheco/arw013

Fayet, A. L., Freeman, R., Anker-Nilssen, T., Diamond, A., Erikstad, K. E., Fifield, D., Fitzsimmons, M. G., Hansen, E. S., Harris, M. P., Jessopp, M., Kouwenberg, A. -L., Kress, S., Mowat, S., Perrins, C. M., Petersen, A., Petersen, I. K., Reiertsen, T. K., Robertson, G. J., Shannon, P., Sigurðsson, I. A., Shoji, A., Wanless, S. & Guilford, T. 2017. Ocean-wide drivers of migration strategies and their influence on population breeding performance in a declining seabird. Current Biology 27: 3871–3878. https://doi.org/10.1016/j.cub.2017.11.009

Fayet, A. L., Clucas G. V., Anker-Nilssen, T., Syposz, M. & Hansen, E. S. 2021. Local prey shortages drive foraging costs and breeding success in a declining seabird, the Atlantic puffin. Journal of Animal Ecology 90: 1152–1164. https://doi.org/10.1111/1365-2656.13442

Frankish, C. K., Manica, A., Clay, T. A., Wood, A. G. & Phillips, R. A. 2022. Ontogeny of movement patterns and habitat selection in juvenile albatrosses. Oikos 2022, e09057. https://doi.org/10.1111/oik.09057

Guilford, T., Freeman, R., Boyle, D., Dean, B., Kirk, H. L., Phillips, R. A. & Perrins, C. M. 2011. A dispersive migration in the Atlantic Puffin and its implications for migratory navigation. PLOS ONE 6: e21336. https://doi.org/10.1371/journal.pone.0021336

Harris, M. P. 1984. Movements and mortality patterns of North Atlantic Puffins as shown by ringing. Bird Study 31: 131–140. https://doi.org/10.1080/00063658409476831

Harris, M. P., Daunt, F., Newell, M., Phillips, R. A. & Wanless, S. 2010. Wintering areas of adult Atlantic puffins Fratercula arctica from a North Sea colony as revealed by geolocation technology. Marine Biology 157: 827–836. https://doi.org/10.1007/s00227-009-1365-0

Harris, M. P., Wanless, S. & Jensen, J. K. 2014. When are Atlantic Puffins Fratercula arctica in the North Sea and around the Faroe Islands flightless? Bird Study 61: 182–192. https://doi.org/10.1080/00063657.2014.909382

Jessopp, M. J., Cronin, M., Doyle, T. K., Wilson, M., McQuatters-Gollop, A., Newton, S. & Phillips, R. A. 2013. Transatlantic migration by post-breeding puffins: a strategy to exploit a temporarily abundant food resource? Marine Biology 160: 2755–2762. https://doi.org/10.1007/s00227-013-2268-7

Lane, J., Pollock, C., Jeavons, R., Sheddan, M., Furness, R. W. & Hamer, K. C. 2021. Postfledging movements, mortality and migration of juvenile northern gannets. Marine Ecology Progress Series 671: 207–218. https://doi.org/10.3354/meps13804

Militão, T., Sanz-Aguilar, A., Rotger, A. & Ramos, R. 2022. Non-breeding distribution and at-sea activity patterns of the smallest European seabird, the European Storm Petrel Hydrobates pelagicus. Ibis 164: 1160–1179. https://doi.org/10.1111/ibi.1306

Monaghan, P. 2007. Early growth conditions, phenotypic development and environmental change. Philosophical Transactions of the Royal Society B 363: 1635–1645. https://doi.org/10.1098/rstb.2007.0011

Morley, T. I., Fayet, A. L., Jessop, H., Veron, P., Veron, M., Clark, J. A. & Wood, M. J. 2017. The seabird wreck in the Bay of Biscay and South-Western Approaches in 2014: a review of reported mortality. Seabird 29: 22–38. https://doi.org/10.61350/sbj.29.22

Phillips, R. A., Xavier, J. C. & Croxall, J. P. 2003. Effects of satellite transmitters on albatrosses and petrels. The Auk 120: 1082–1090. https://doi.org/10.1093/auk/120.4.1082

Phillips, R. A., Silk, J. R. D., Croxall, J. P., Afanasyev, V. & Briggs D. R. 2004. Accuracy of geolocation estimates for flying seabirds. Marine Ecology Progress Series 266: 265–272. https://doi.org/10.3354/meps266265

Reiertsen, T. K., Layton-Matthews, K., Erikstad, K. E., Hodges, K., Ballesteros, M., Anker-Nilssen, T., Barrett, R., Benjaminsen, S., Bogdanova, M., ChristensenDalsgaard, S., Daunt, F., Dehnhard, N., Harris, M., Langset, M., Lorentsen, S., Newell, M., Bråthen, V., Støyle-Bringsvor, I., Systad, G. H. & Wanless, S. 2021. Interpopulation synchrony in adult survival and effects of climate and extreme weather in non-breeding areas of Atlantic puffins. Marine Ecology Progress Series 676: 219–231. https://doi.org/10.3354/meps13809

Roman, L., Hardesty, B. D., Hindell, M. A. & Wilcox, C. 2020. Disentangling the influence of taxa, behaviour and debris ingestion on seabird mortality. Environmental Research Letters 15: 124071. https://doi.org/10.1088/1748-9326/abcc8e

Sæther, B. E., Coulson, T., Grøtan, V., Engen, S., Altwegg, R., Armitage, K. B., Barbraud, C., Becker, P. H., Blumstein, D. T., Dobson, F. S., Festa-Bianchet, M., Gaillard, J. M., Jenkins, A., Jones, C., Nicoll, M. A. C., Norris, K., Oli, M. K., Ozgul, A. & Weimerskirch, H. 2013. How life history influences population dynamics in fluctuating environments. The American Naturalist 182: 743–759. https://doi.org/10.1086/673497

Stubbings, E., Bueche, B., Miquel Riera, E., Green, R. M. & Wood, M. J. 2016. Seabird monitoring on Skomer Island in 2016. JNCC Report, No. 297. Joint Nature Conservation Committee, Peterborough.

Weimerskirch, H. & Wilson, R. P. 2000. Oceanic respite for wandering albatrosses. Nature 406: 955–956. https://doi.org/10.1038/35023068

Weimerskirch, H., Corbeau, A., Pajot, A., Patrick, S. C. & Collet, J. 2023. Albatrosses develop attraction to fishing vessels during immaturity but avoid them at old age. Proceedings of the Royal Society B. 290: 20222252. https://doi.org/10.1098/rspb.2022.2252

Wienecke, B., Raymond, B. & Robertson, G. 2010. Maiden journey of fledgling emperor penguins from the Mawson Coast, East Antarctica. Marine Ecology Progress Series 410: 269–282. https://doi.org/10.3354/meps08629

Wynn, J., Guilford, T., Padget, O., Perrins, C. M., McKee, N., Gillies, N., Tyson, C., Dean, B., Kirk, H. & Fayet, A. L. 2022. Early-life development of contrasting outbound and return migration routes in a long-lived seabird. Ibis 164: 596–602. https://doi.org/10.1111/ibi.13030

Yoda, K., Yamamoto, T., Suzuki, H., Matsumoto, S., Müller, M. & Yamamoto, M. 2017. Compass orientation drives naïve pelagic seabirds to cross mountain ranges. Current Biology 27: R1152–R1153. https://doi.org/10.1016/j.cub.2017.09.009

Data availability

The data are available on the BirdLife Seabird Tracking database (www.seabirdtracking.org).