AUTHOR BLOG: A new hummingbird species in Ecuador

Juan Freile

Linked paper: A striking, critically endangered, new species of hillstar (Trochilidae: Oreotrochilus) from the southwestern Andes of Ecuador by F. Sornoza-Molina, J.F. Freile, J. Nilsson, N. Krabbe, and E. Bonaccorso, The Auk: Ornithological Advances 135:4, October 2018.

Adult male (above left, center right), adult female (below), and immature male (above right) Oreotrochilus cyanolaemus. Image credit: P. Greenfield.

Last year a new hummingbird species was unexpectedly discovered on a seldom-visited mountain top in southern Ecuador. A brief visit to the rocky outcrops of Cerro de Arcos in the southern province of El Oro produced a photographic record that rang a bell: a mysterious immature male clearly assignable to the genus Oreotrochilus, the hillstars, which included six species at the time. A few days later, an adult male was captured in another photo, and a week after that, several males and females were observed and a handful collected for scientific purposes.

Such an outstanding discovery needed a thorough assessment to understand the taxonomic status and phylogenetic relationships of the putative new species and their evolutionary implications for the genus Oreotrochilus. This genus is remarkable in being the one that reaches the highest elevations: records above 4,500 meters, with a mean of 3,600 meters above sea level. As such, these hummingbirds need a very special set of physiological and behavioral adaptations to feed on the scarce nectar resources available. One plant in particular is extremely important for the hillstars—the spiny-leaved Chuquiragua, with its fire-orange flowers.

The newly discovered hillstar of southern Ecuador is not an exception in its feeding associations. In fact, its geographic range seems to be shaped by the availability of Chuquiragua in a very restricted region between the geographic ranges of the Ecuadorian Hillstar, Oreotrochilus chimborazo, found in Ecuador and extreme southern Colombia, and the Green-headed Hillstar, Oreotrochilus stolzmanni, found in Peru and extreme southern Ecuador.

The latter species is likely the closest relative to the new species, sharing an overall plumage pattern and being very similar genetically. But a single striking characteristic sets them apart: the Green-headed Hillstar has a glittering lime-green throat patch, or gorget, whereas the gorget in the new species is a glittering deep blue. Given that gorgets are likely used in courtship displays by males, the strikingly different color suggests that reproductive isolation is effectively segregating these taxa.

Being extremely restricted in distribution, confined to a few mountain tops where habitat degradation is dramatic, the conservation status of this new hillstar seems critical. No conservation projects exist across its tiny range; on the contrary, the agricultural boundary is progressing, cattle graze free in the few natural grasslands that remain, burns are frequent every windy summer, and not a few mining concession cover the area. Urgent research and conservation actions are on the way, but there is little time left.