When cats see a bird (versus a potential prey animal that walks or runs), their vocalization is characterized as a "chitter." (It sounds a lot like they are trying to imitate a bird. My cat sounds like he is saying "Eh-- ah-- eh-- eh-- eh!" It is distinct to either birds or sometimes flying insects, though he usually doesn't bother to chitter for just an insect. When he is hunting mice, he is silent.) So probably your cat has a remark she reserves for the particular animal she saw.
I read an article a couple of years ago, which stated that distinctive vocalizations made by domestic cats have been recorded in a number exceeding 120...while those made by dogs number at about 2 - 3 dozen.
All 8 cats Anita and I have had, plus the 3 her family had that I knew and the 3 my family had, each had their own voice.
The range of both volume and register has been amazing, from deep bass "rowr" to high pitched "squeek."
So, yes, it is quite possible your girl is vocalizing quite close to a bark.
You may be talking about cough-barking, which is very rare in cats but does exist... if I understand what you mean. My cat Dillan does the same thing when he sees birds. He also does the chirp thing, and chatters a lot. They can make numerous sounds. I think it's very cute. Some say they do it off of pure frustration of not being able to catch the bird. I'd say it's just predatory instincts kicking in.
PK