NESTING OF THE YUCATAN VIREO, VIREO MAGISTER, IN MAINLAND MEXICO AND ON ISLA COZUMEL, WITH DETAILS OF BREEDING PHENOLOGY

Abstract

We report the first definitive Mexican breeding records of the range-restricted Yucatan Vireo (Vireo magister). We discovered two V. magister nests in July and August 2009 in Sian Ka’an Biosphere Reserve (near Tulum) and one nest on Isla Cozumel in June 2009. We observed two possible additional V. magister nests with eggs in Sian Ka’an in 2009, one each in June and July. All nests were open cups woven onto branches and hung beneath forks. Clutch size was two eggs at definitive V. magister nests. Nests and eggs were similar to those of most Vireo spp., including sympatric nesting congeners. Breeding activities—including egg-laying, incubation, and nestling and post-fledging provisioning—at definite Yucatan Vireo nests occurred in June and July on Cozumel and July and August on the mainland. Incubation and nestling stages lasted ~ 15 days and ~ 14 days, respectively. Yucatan Vireo remains poorly known, warranting further study.