These ducks are the marks left behind by the ghost of St Cuthbert - patron saint of ducks - as he does battle defending the manuscripts against Titivillus. The demon goes to insert errors into the script, sees a misplaced duck, and thinks to itself 'drat, someone has beat me to it'
It would be downright heretical to ink over such a blessed addition to the manuscript
It is also my headcanon that the guy was done and a child came up and doodled a duck onto the page
Honestly looks like it, since it's not been inked! There's someone who sneaks into the monastery at night and adds ducks to all their new manuscripts.
These ducks are the marks left behind by the ghost of St Cuthbert - patron saint of ducks - as he does battle defending the manuscripts against Titivillus. The demon goes to insert errors into the script, sees a misplaced duck, and thinks to itself 'drat, someone has beat me to it'
It would be downright heretical to ink over such a blessed addition to the manuscript