Fair comment but grit will atract a certain moisture in this climate no matter where it is, and dust as well
The minute we all let our pigeons out, you open them to elements beyond our control
The pick freely at dusty, moist, possibly contaminated elements around our lofts and cotes
Pigeons seem to thrive on grit scatterd on the road both moist and dry
On the bath comment our pigeons come out for a bath and sortly after re-enter the loft to feed their young, so I think moisture is present quite alot in the loft apart from drinking water
Just for interest
I worked with fire retardent stone dust that was important that if stayed dry, when an explosion occured it blew the stone dust "airbound" and starved the fire of air, so if had a cetain level of moisture it behaved differently,
Some pigeon boys used to take home bags of red stone for their pigeons