had to smile at the above post rather politely put ;D,,,,,,,,,,,why is it that when sitting a while? and [as politeley says above ;D],, they will patiently wait on you cleaning the loft, putting fresh grit/minerals and water in,,,,,then the birds will come off their eggs ,, back up to one of these galley pots or drinkers, [usually pick the cleanest one ;D] then kindly drop their" loaded" load ,,,,,right in the dish,, ;D [im sure they do this on purpose ;D]
anyway,,when feeding yb,s i find feeding maples , which contain plenty fibre, seems to keep the yb,s droppings firm,,,