I collated how much your birds seem to eat, with how much my birds do eat, with this data:
http://www2.ca.uky.edu/afspoultry-files/pubs/How_much_will_my_chicken_eat.pdf
So obviously bantams and lighter or more economical birds such as silkies and leghorns etc, will eat less than an equal number of dog sized chickens... (which is why factory/battery farms employ leghorns and not Jersey Giants)
I have a mixed flock, (2 lightweight EEs, a leghorn, 2 large/heavy EEs and 2 Wyandottes)... and my flock's average daily consumption per bird comes out to .19 lbs each daily.
This link suggests .25 lb of feed per day per bird as a rule of thumb. Rules of thumb tend to weight recommended values to blanket all scenarios.