GPS tracking of Eurasian curlew breeding pairs reveals longer incubation times in males

GENERAL INFORMATION 1. Paper Citation GPS tracking of Eurasian curlew breeding pairs reveals longer incubation times in males. 2. Brief abstract Many species of shorebirds are socially monogamous and therefore exhibit biparental incubation. This form of cooperation between parents is not always fair, as they must cope with their incubation duties while allocating time to maintenance activities. By monitoring each partner throughout the breeding season, on-board telemetry devices offer new opportunities to understand cooperation between mates. Hence, this study aims to characterise parental effort during the incubation period in the Eurasian curlew. A total of 88 curlews were tagged with GPS devices in France between 2020 and 2025. Sixty-one individuals (21 females and 40 males) were used to compare incubation time, the average distance to the nest, and off-nest activities according to sex and the diurnal cycle. In addition, five breeding pairs with both tagged mates provided information on parental cooperation throughout the breeding season. Overall, males incubated for longer on average than females in 24 h periods (mean ± SD: males 12 h 05 ± 2 h 24 vs females 7 h 54 ± 1 h 45), particularly in relation to their nocturnal incubation. They often remained closer to the nest, allowing them to replace the female on the nest in case of her temporary absence. Remarkably, females did not necessarily feed for a large part of the night, instead reaching most night-time rest areas shared with congeners. This study therefore highlights cooperation between mates during incubation, with a greater parental effort by males; this may be beneficial to both parents by improving the chances of successful breeding across years. 3. Originator 4. Contact information 5. Date of data collection Data were collected between 2020 and 2025. 6. Geographic location(s) of data collection France 7. Information about funding sources that supported the collection and curation of the data This work was supported by the Contrat de Plan Etat-Région (ECONAT project), the Centre National de la Recherche Scientifique (CNRS), the European Regional Development Fund (QUALIDRIS project), the Office Français de la Biodiversité (OFB), the Département des Deux-Sèvres, and the Humus Fondation. The GPS tags from the National Museum of Paris were funded by the Agence Française de Développement (AFD) and the Ministère français en charge de l’Ecologie (BirdMan project). This study is included in the HABITRACK project funded by the European Union through their HORIZON Research and Innovation Actions (project 101135047, HORIZON-CL6-2023-BIODIV-01-Biodiversity and ecosystem services). Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them. ACCESS INFORMATION 1. Licenses/restrictions placed on the data CC-BY 4.0 Attribution 4.0 International DATA FILES AND VARIABLES 1. Metadata DescriptionDatabase containing an overview of the breeding phenology of all the individuals used in the study. Variables • Breeding event retained for incubation times: Birds and seasons retained for arrival and departure dates, proportions of incubation time, and average distance to nest analyses (n=59 individuals). • Breeding event retained for night-time activities: Birds and seasons retained for the definition of night-time activities analyses (n=61 individuals). • Bird ID: Bird unique identifier. • Season: Year of monitoring. • Gender: M: male; F: female • Breeding partner: Bird ID of the breeding partner if known. • Bird ID Season: • Tagging Country: Country were individuals have been tagged with a GPS device. • Site: Breeding site. • Age: Only adults (A). • First Latitude: Latitude of the bird's catching site. • First Longitude: Longitude of the bird's catching site. • Device number: GPS tag identifier. • Complete event: A complete event is an event where the arrival and departure dates of the individual at the breeding site are known thanks to the GPS tag • Breeding number: Breeding season number of each individual • Breeding start date local hour (20km): Date of the first GPS fix within the breeding area. Since some birds are caught during the breeding season, this date does not necessarily correspond to the bird's arrival date at the site. • Breeding end date local hour (20km): Date of the last GPS fix within the breeding area. Since some birds lose their GPS tag during the breeding season, this date does not necessarily correspond to the bird's departure date from the site. • Duration (days): Duration between the first and last GPS fix within the breeding area. • Breeding country: • Nest position known: • Complete incubation available: An incubation is considered complete if it lasts at least 28 days. • Nest Latitude: • Nest Longitude: • Nest 2 Latitude: • Nest 2 Longitude: • Arrival date: Real bird's arrival date at the breeding site. • Laying date: • Fail date: • Hatching date: • Hatching success: When incubation last a minimum of 28 days. • Breeding success: When chicks have been observed at least 7 days after the hatching date. • Second clutch or not: • Laying date of second clutch: • Fail date of second clutch: • Hatching date of second clutch: • Hatching success of second clutch: • Breeding success of second clutch: • End date: Real bird's departure date from the breeding site. 2. Curlew_database DescriptionDatabase containing the GPS data obtained during the breeding season of all the individuals used in the study. Variables • Bird ID: Bird unique identifier. • Country Tagged: Country were individuals have been tagged with a GPS device. • Site: Breeding site. • Date Time: • Season: Year of monitoring. • Activity: Breeding. • Distance from Site: • Site Latitude: • Site Longitude: • Time interval: Time interval between two GPS fixes. • Latitude: • Longitude: • Breeding Country: • Wintering Country: • Hrise: Sunrise time according to the bird's position. • Hset: Sunset time according to the bird's position. • ID_day_night: • DateTimeLocal: • Datatype: • Satcount: Number of satellites used to define the bird's position. • Date: • Time: • Bird.ID_Season: