The word was originally introduced to English in the 16th century and, at that time, there were two predominant versions: A French/Spanish version (with an “r” in the middle; this officially came from French but the Spanish version was similar) and an Italian version (with an “l” in the middle). Naturally, we adopted the “r” version in our spoken language and the “l” version in our written language.
Such a weird phenomenon. That makes me wonder if there are any other words that were assimilated into English that way. Up until recently, it’s been said that the average English-speaking adult knows about twenty-thousand, though I have heard, some time in the past year or two, that the average adult might know as many as eighty or one-hundred thousand words. This is probably not the only word that has experienced this.
A “Full Bird” colonel is an unofficial label that differentiates a full colonel from a lieutenant colonel. I was unable to find why it mentions a bird.