Tail feathers and “love signals” have split a type of tiny “bee hummingbird,” the Bahama Woodstar, into two distinct species.
Researchers claim that this newest bird species has been discovered, not in some remote tropical jungle, but in backyards in the Bahamas.
“Much of the fieldwork was literally conducted sitting at the backyard tables of birders, holding the sound recorder in one hand and a cup of tea in the other,” explains Teresa Feo, a doctoral student at Yale University and lead author of the study.
The Bahama Woodstar species contains two subspecies, one found throughout the northern islands of the Bahamas, the other found only among the southern Inaguan islands of the chain. Both males and females of the two are virtually identical but in this case appearances were deceiving.
Pops and whistles
Feo teamed up with ornithologist Christopher Clark from the University of California, Riverside, to record the pops and whistles produced when air runs along male tail feathers during mating display dives.
Feo and Clark found that minor differences in the tail feathers between the two subspecies—one has a more forked tail than the other—resulted in distinct visual and acoustic love signals so that males would attract only females of their own kind.
Feo and Clark additionally found differences in vocalizations. Males from the more widespread subspecies in the northern islands produced the classic hummingbird “light tinkling, rambling songs,” while males from the southern islands sounded more like “wet squeaky shoes.” The birds also emitted different calls and scolding sounds, indicating a long history of geographic separation.
The researchers also compared beak and wing lengths, and collected tissue samples from the two populations for subsequent genetic analysis. Doctoral students Jacob Berv from the Cornell Lab of Ornithology and Jacob Musser from Yale worked together to sequence the birds’ DNA, and found many species-level differences that indicated these populations have evolved in isolation for about half a million years.
The researchers conclude that the northern islands subspecies should keep the familiar name, “Bahama Woodstar” (Calliphlox evelynae evelynae), and suggest “Inaguan Lyretail” (Calliphlox evelynae lyrura) for the other subspecies, because it is found only among the southern Inaguan Islands of the Bahamas and because its forked tail shape resembles a classical lyre harp.
The team will next petition the American Ornithologists’ Union to officially recognize the new species.
“There’s a big wide world out there and a lot to learn about birds,” reflects Feo, “and sometimes there’s new stuff to learn even in your own backyard.”
The National Science Foundation and the W.R. Coe Funds from Yale University supported the work. The study appears online in The Auk.
Source: Cornell University