Wingbeat frequency scales inversely with wing size across flying animals, so a larger hummingbird necessarily flaps more slowly. Where a small hummingbird beats its wings several dozen times a second, the giant hummingbird's strokes are individually visible, and its flight has been described as more like a swift or a falcon than a typical hummingbird.
Size also changes the energy budget in the bird's favour. A larger body loses heat more slowly, which matters in the cold, dry high Andes where the species feeds at cactus flowers, Puya and introduced eucalypts. It still hovers to feed, but perches at flowers more readily than smaller relatives.
Genetic work published in 2024 established that what had been treated as one species is in fact two: a resident northern form and a migratory southern form that breeds in Chile and Argentina and moves north into the high Andes. Their appearance is nearly identical, so field identification and older distribution records are now unreliable.