2.1 Capture and tagging of vultures
From 2014 to 2022, we captured 127 adult Griffon Vultures (43 males and 84 females) in 5 breeding regions distributed across northern (Alto Ebro: 49 individuals, Pyrenees: 21 individuals), central (Segovia: 15 individuals), and southern Spain (Cádiz: 12 individuals and Cazorla: 30 individuals) (see Fig 1). Breeding regions were delimited according to the proximity between nesting sites and the biogeographic characteristics of each area where nests are located. Birds were trapped using remotely activated cannon nets and cage traps baited with livestock carcasses. Individuals were tagged with yellow or blue plastic alphanumeric and metal rings and equipped with solar-powered GPS/GSM transmitters (Ecotone https://ecotone-telemetry.com/en, Ornitela https://www.ornitela.com/, and e-Obs https://e-obs.de/). The total weight of the transmitters and rings did not exceed 64g, which represented less than 3% of the body weight of the individuals (Bodey et al., 2018). The age of individuals was estimated from plumage moult (Donázar, 1993; Zuberogoitia et al., 2013), while sex was determined using molecular sexing techniques (Fridolfsson et al .,1999).
Tracking devices were programmed to record fixes (i.e. GPS positions) at 5-10 min intervals from 1 h before sunrise to 1 h after sunset (see Table 1 for details of the tracking devices and sampling frequency). GPS data were incorporated into the Movebank online data repository (www.movebank.org). Data were standardised by resampling the GPS fixes to 15 min for each individual to homogenising our dataset. Vultures were tracked on average 1,040 ± 809 days with a mean number of fixes per individual of 41,335 ± 40,493.