Where to head: environmental conditions shape foraging destinations in a critically endangered seabird

10 pages, 4 figures.-- Data availability: All relevant data are publicly available in the Seabird Tracking Database: http://seabirdtracking.org/mapper/?dataset_id=879 and http://seabirdtracking.org/mapper/?dataset_id=1409Foraging distribution of flying seabirds is constrained by environmental factors influencing individual decision-making. This must be particularly true during the breeding period, when individuals face additional limitations imposed by their central-place foraging behaviour. We used GPS data loggers and Argos PTTs to track the foraging flights of Balearic shearwaters (Puffinus mauretanicus) during the chick-rearing period of 2011–2014 in the Balearic Islands (Western Mediterranean). We identified main areas used by tracked birds and characterised their productivity patterns. Based on a spatial seascape approach of flight costs varying with time, shaped by environmental processes as winds, we also estimated flight costs to reach foraging grounds in outward and return trips from the colony. Individuals repeatedly used the closest areas on the Iberian continental shelf. However, sporadic and favourable wind conditions facilitated low-cost flight to more distant and equally productive areas of the western North African shelfFunding support was provided to LPO and SEO/BirdLife through Interreg project FAME, LIFE + project INDEMARES, and the Ibiza Preservation Fund, and to the IEO through a Marie Curie Career Integration Grant (CONPELHAB; PCIG09-GA-2011-293774). ML was funded by a Juan de la Cierva (JCI-2010-07639) and a Ramón y Cajal (RYC-2012-09897) postdoctoral contract. FR was funded by a Juan de la Cierva (JCI-2015-24531) postdoctoral contractWith the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)Peer reviewe