Scientists are unraveling the conservation risks to the elusive Bicknell’s Thrush. A Bicknell's Thrush banded in Vermont. A blood sample is required to distinguish between females and males. Photo: Michael Sargent On a hazy day in late September 2025, Desiree Narango walked the sandy paths at the Foreman’s Branch Bird Observatory in coastal Maryland looking for the secretive and rare Bicknell’s Thrush. The songbird—hard to identify and few in number—only stops here briefly to rest and refuel on its migration south to the Caribbean. But she was hoping to get lucky and catch a few to help solve a two-decade mystery: Why were there so few females?  In the early 2000s, Jim Goetz, a conservation scientist at the Vermont Center for Ecostudies (VCE), published his observation that male Bicknell’s Thrushes outnumbered females at two sites in Vermont, where they breed. Concerningly, the ratio could be as skewed as eight males for each female.…