After snapping a single shot, Ammann watched as the cardinal flew away. But that was all the evidence he needed to start solving this mystery of the two-tone cardinal.
"In just a few hours I learned, in a reply to one of my Web queries, that this bird is an extremely rare bilateral gynandromorph cardinal," Ammann said.
"Quite a mouthful to say, but this means a genetic mistake occurred during the first cell division of the fertilized ovum, causing one of the cells produced by this division to be male and the other to be female. As this egg developed, the entire right side remained female and the left side remained male," Ammann continued.
This condition isn't unheard of in other birds, but is particularly noticeable in cardinals.
"The obvious differences in coloration between male and female cardinals, referred to as sexual dimorphism, makes gynandromorphy very noticeable when it occurs in cardinals," he explained.