An Eccentric Preformative Molt with Incomplete Replacement of Primary Coverts in a Dark-eyed Junco

Abstract

Though the Dark-eyed Junco has not been reported to replace any juvenile primaries during its preformative molt, one first-cycle bird captured at Stanford, California, in November 2022 had replaced all its remiges but the three innermost primaries. Thus it followed the eccentric pattern more frequently seen in other sparrows, wrens, and some tyrant flycatchers. This novel pattern may be an adaptation to the urban habitats that the junco has recently colonized.