Paint Eating Blue Jay

I came across an interesting bit of blue jay lore in a recent issue of Birdwatching magazine and thought I would share.  Someone had witnessed a blue jay taking paint chips off of their house and eating them.  Seems there is a form of calcium  in paint (calcium carbonate) which attracted the jay to this mineral source.  Since those of the avian persuasion cannot store calcium in their bodies they must get it from other sources, such as egg shells, grit, bone fragments from raptor pellets, sand, ashes, or any prey that has a calcium-laden exoskeleton.  Also I've read of hummingbirds drinking seawater for minerals.  And now we can add house paint to the list.  What I want to know is......how do birds know these things??

Suggested Reading:

Do Band-Tailed Pigeons Seek a Calcium Supplement at Mineral Sites
Hummingbird Drinking Seawater

Hummingbirds Eating Ashes

Some Observations of Birds Eating Salt
Laying Red-Cockaded Woodpeckers Cache Bone Fragments