Why these tiny, owl-like birds are actually the secret cousins of hummingbirds

Nature · Published 3 October 2026 Swipe more like this →

In short: The owlet-nightjar looks like a miniature owl, but this Australasian insectivore is a master of evolutionary misdirection. While long grouped with nightjars and frogmouths, modern molecular science reveals their true lineage is far more surprising, linking them to the ancestors of today's swifts and hummingbirds.

The owlet-nightjar, belonging to the monotypic family Aegothelidae, has long been a subject of taxonomic debate. In the 19th century, naturalists classified them alongside frogmouths and nightjars due to their shared physical traits: soft, cryptic plumage, wide gapes, and insectivorous habits. However, morphological studies of the cranium in the 1960s began to challenge this, suggesting they deserved their own distinct order, Aegotheliformes. This classification was later bolstered by molecular phylogenetic research.

A comprehensive 2003 study analyzing mitochondrial DNA sequences provided the breakthrough, revealing that owlet-nightjars are not as closely related to nightjars as previously assumed. Instead, they share a more recent common ancestor with the Apodiformes—the order containing swifts, treeswifts, and hummingbirds. These two groups, the Aegotheliformes and Apodiformes, diverged from a common ancestor approximately 57 million years ago. Together, they form a clade known as Daedalornithes, which sits within the larger Cypselomorphae group.

This evolutionary connection explains why the ancestors of modern swifts and hummingbirds likely resembled small owlet-nightjars. While today's swifts and hummingbirds have become highly specialized—with reduced legs and narrow bills—the owlet-nightjar retains the ancestral body plan of strong legs and a wide, whisker-fringed gape. Though they are now restricted to Australasia, fossil evidence, such as the 19 to 16 million-year-old specimens found in New Zealand's Bannockburn Formation, indicates that their relatives once thrived across Eurasia during the late Paleogene.

Today, the IOC World Bird List recognizes ten living species, ranging from the Australian owlet-nightjar to the elusive, likely extinct New Caledonian owlet-nightjar. Despite their owl-like appearance, they remain a distinct, ancient lineage that offers a rare glimpse into the ancestral form of some of the world's most specialized avian groups.

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