Fig. 1
From: Origin and cross-century dynamics of an avian hybrid zone
Phenotypic variation in male specimens collected along the Ramphocelus flammigerus hybrid zone in southwestern Colombia. Individuals 1-6 correspond to R. flammigerus icteronotus (yellow-rumped form) from the plains of the Pacific coast (sector 1; see Fig. 2). On the other extreme, individuals 11-14 correspond to R. flammigerus flammigerus (scarlet-rumped form) distributed towards the Cauca River Valley (sector 3). Individuals 7-10 are intermediates collected near the center of the hybrid zone (sector 2)