Dr. Jay Falk’s research centered on the fascinating white-necked jacobin hummingbird. While the males boast a vibrant deep blue iridescent head, bright white belly, and an attention-grabbing white tail, most females present a distinct mottled gray throat and belly with a dark, almost black, tail. Intrigued by an unusual observation, Falk noted that a significant 20 percent of female jacobins exhibit coloration almost identical to that of males. The driving force behind this male mimicry, he discovered, is purely practical: it grants these females better access to food resources like nectar. By resembling males, they successfully avoid the aggressive territorial behavior of other hummingbirds, which are notoriously vicious.
A pivotal discovery in his work was identifying a single gene likely responsible for this remarkable color variation among female hummingbirds. This finding is particularly noteworthy because such complex phenotypic changes are typically controlled by multiple genes, not just one. Further investigation revealed that this gene produces a thyroid hormone, which Falk initially didn’t expect to have such a profound impact on physical traits.
A vivid photograph by Daniel Brenner for The New York Times shows a white-necked jacobin hummingbird in mid-flight. The image prominently displays its iridescent blue head and white tail, highlighting the very features central to Jay Falk’s research on why some female birds mimic male plumage.
This specific study, though focused on a single species, contributes to a much larger and critically important scientific field: understanding the intricate connection between genetic variation and the physical forms we observe in nature. It delves into the fundamental question of how genes give rise to diverse bodies, a question with parallels to how our own genes influence health. Falk’s research aimed to meticulously connect these dots, for instance, by investigating how changes in thyroid hormone could selectively impact feather coloration without affecting other aspects of the bird’s physiology.
“I don’t know why my fellowship was terminated. I suspect that it has something to do with studying a species that doesn’t fit the binary.”
This vital research, however, was abruptly halted when Dr. Falk received an email on April 25, terminating his postdoctoral research fellowship from the National Science Foundation. He remains uncertain about the exact reasons for this decision, though he speculates it might be related to his focus on a species that challenges traditional binary understandings of male and female appearances in nature. After dedicating over a decade to this work, Falk describes his current situation as a “weird limbo state.” The sudden lack of funding has left him questioning his future in science, as the signs suggest a dwindling path forward for his groundbreaking studies.