Methods
We captured 42 adult feral pigeons (Columba livia ) from two
free-living populations located 50 km apart, one in Barcelona (DD
coordinates: 41.38879, -2.15899, n = 23 pigeons) and another from MoiĆ
(41.81112-2.09839, n = 19). The two populations show substantial
differences in their foraging ecology, with individuals from Barcelona
spending more time foraging and relying more on active searching for
food than on sit-and-wait strategies than those form MoiĆ (Sol 2008).
After capture, individuals were measured (wing, tail, tarsus and beak
lengths), banded with a unique combination of coloured rings, and
randomly assigned to four outdoor aviaries of 2x4x2 m (8-12 individuals
from the same population). Each aviary was provided with roosting sites,ad libitum food (a commercial mixture of food) and water. For the
experiments, individuals were relocated in individual cages of 70x50x40
cm containing a feeder and a watering bowl. Experimental cages were
located indoors, to homogenize the conditions in which assays were
conducted. During assays, birds were observed from behind a blind to
avoid disturbance by the observer. Six individuals were tested
simultaneously, assigned at random within each of the four outdoor
aviaries. Experiments were videotaped and behaviour was scored using the
software Jwatcher (https://www.jwatcher.ucla.edu/). All animal care,
husbandry, and experimental procedures were in accordance with the
Spanish code of practice for the care and use of animals for scientific
purposes and were approved by the Generalitat de Catalunya (0152S).