A species of bird first described in 1957, but then not seen again until its rediscovery 45 years later, is even more mysterious than previously thought. It turns out that the golden-crowned manakin – a small, vivid green bird with a yellow noggin – is actually the result of a hybridization event between two other species of manakin birds.

While hybridization among vertebrates in the wild is rare, it does still happen. We've seen this occur, for example, with grizzly and polar bears in the Arctic. Even rarer, however, is when these hybrids become reproductively isolated from either of their parents and go on to form their own population (and eventually their own species).

There are a handful of known cases of this occurring, such as red wolves in the eastern United States and the Clymene dolphin in the Atlantic Ocean. This latest example, though, is the first known case of a hybrid bird species found in the Amazon rainforest. The discovery is reported in the Proceedings of the National Academy of Sciences.

Genetic tests of the elusive species (Lepidothrix vilasboasi) reveal that it's the result of a hybridization event that occurred between the snow-capped manakin and the opal-crowned manakin some 180,000 years ago. It is thought that the configuration of the landscape in this region led to the hybrid being isolated from both species and eventually its evolution into a new species.

Interestingly, the distinctive golden head on the males – which sets them apart from either of the parent species – is likely a result of this hybridization event. Looking at the keratin structure of the crown feathers, they found some striking differences. Both parent species have a distinctive keratin structure, giving one a bright white head and the other highly reflective feathers. This allows both males and females to spot each other in the dim light of the forest. The keratin structure seen in the feathers of the golden-crowned manakin, however, show a mix of both parents.

“The golden-crowned manakin ended up with an intermediate keratin structure that does a poor job of making either the brilliant white or the reflective iridescence of the parental species,” explains study co-author Jason Weir in a statement.

It is likely that soon after the hybridization event, the species had a dull white or grey head. Only later did the males evolve a golden crown on their head to increase their visibility in the forest. This resulted in the unique colors now seen in each of the three species.