The Bachman’s Warbler is often cited as the rarest songbird of the United States. This is because it is, most likely, extinct. Much like the infamous Ivory-billed Woodpecker, the Bachman’s Warbler has not definitively been sighted in decades, since 1937 to be precise. It is one of the only recent bird extinctions in North America. Due to its extinction, this yellow and gray warbler has become something of a symbol for conservation and the preservation of endangered birds.
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Few birders today can remember a time when the Bachman’s Warbler when this bird was still known to occupy the thicketed forests of its natural range, which included limited tracts of the American South. Instead, most of us recognize this bird as a representative of the birds which have disappeared during mankind’s time on earth, alongside the aforementioned Ivory-billed Woodpecker and the infamously ill-fated Dodo.
Now, a recent research effort offers some insight into the biology of this lost warbler. The study, which comes from Penn State, has successfully sequenced the genome of the Bachman’s Warbler, using preserved museum specimens. There are several Bachman’s Warbler specimens still in existence, but this is the first time their genes have been sequenced.
The study examined Bachman’s Warbler genes alongside the genes of their closest living relatives, the Golden-winged and Blue-winged Warblers. These two species look distinct, but hybridize often, so the study provided valuable insight into the genetic differences between the two. It has also been questioned, at times, whether the Bachman’s Warbler was ever really a distinct separate species.
What was discovered may have as much of an effect on how these living warblers are understood as the Bachman’s Warbler. It was found that the Blue-winged and Golden-winged warblers share large portions of their genome and that the majority of the deviations occur in the genes concerned with feather colors. This explains why the two so readily hybridize.
On the other hand, the genes of the Bachman’s Warbler did not align with the other two species. The study has contributed significant, perhaps conclusive evidence that the Bachman’s Warbler was its own distinct species, rather than a variation upon a close relative.
In a way, these revelations are bittersweet. It is fascinating to know more about these birds that have been gone from this earth for almost a century. Learning that their genome is so distinct, that there is no living bird quite like them, comes with a renewed sense of loss and a renewed determination to protect the living birds which face the same challenges as the Bachman’s Warbler.
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