Stopover on Galapagos During Autumn Migration of Bobolinks (Dolichonyx oryzivorus)

Abstract

ABSTRACT The Bobolink (Dolichonyx oryzivorus) is the only landbird species that is known to stop every year in Galapagos while migrating; however, its stopover ecology while on the islands is unknown. In October 2015, we searched for and captured Bobolinks in the highlands of San Cristobal. We found Bobolinks in two fields, separated by 9.15 km, at ∼425 m elevation. Average daily counts of Bobolinks on these two fields were 3.2 ± 1.8 and 4.8 ± 2.3 individuals. We caught nine individuals; body mass and fat reserves varied from 22.5–40.0 g and no fat reserves to 50–100% reserves, respectively. Both fields were dominated by grasses ranging in height from 30 cm to >100 cm, and included purple cuphea (Cuphea sp.). Other habitats we surveyed, where we did not observe Bobolinks, included closely cropped grass (5–10 cm), taller grasses with seed and with scattered to dense guava trees (Psidium guajava), and small (0.1–0.3 ha) corn plantations with seed. Six of the birds we caught had seeds of Drymaria cordata ent...