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.