I lost a couple right after I switched to shavings.... Best to use that Rubbermaid shelf liner or Regular towels you have to wash.... or Grass hay with no seeds in it. I think Peeps uses the last.
I use the rubberized shelf liner, old towels and textured paper towels for a day or 2 until I see them eating their starter feed well, then I switch to grassy hay or straw. The tannins in the shavings can be toxic to the keets, even if they are kiln dried... but yah, ingesting them clogs them up and kills them super fast.
Sorry you lost 6 keets Ash