Photo: Ken Jones
More migration-based research is showing that Ruby-throated Hummingbirds appear to have adopted a mixed strategy concerning migration. Some adults choose to fatten up before migrating from Canada and the US. to wintering grounds in Central America. They gorge at feeders to increase their body mass by more than 33%. However, juvenile 'hummers' do not appear to do this, likely stopping to feed along the way.
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BarrytheBirder