What military insignia inspired the "Yellowhammer" nickname for Alabama Confederate troops?

Red-and-yellow woodpecker insignia

The designation of the Yellowhammer as the State Bird of Alabama is rooted in a historical nickname applied to Confederate soldiers from that state during the American Civil War. Soldiers from other states referred to the Alabamians as "Yellowhammers." The generally accepted origin of this transferrable moniker stems from the distinctive insignia worn on the vests of these troops, which depicted a red-and-yellow woodpecker. This particular woodpecker species is sometimes locally referred to as a yellowhammer in that region, leading to the nickname being applied either directly to the bird species *Emberiza citrinella* or to a bird the soldiers associated with their home, solidifying a cultural identity in 1927 despite the bird not being native to the area.