I posted a while ago about my kittens using the tray as a playpen. That's resolved itself now, but I've started noticing a bit of interesting behaviour and wanted to ask if anyone has seen this before. Bonkers is an expert burier, honestly you need to mount an archeological dig to find his poops, whereas Boo Boo just gives the most cursory of coverings and trots off. I've noticed that, when Boo Boo uses the tray, Bonkers waits patiently outside then, when he's finished, will go in and spend a few minutes covering Boo Boo's 'work' to his standards. This is even though I am pretty quick with the scoop and will normally have poop or pee out and flushed within seconds of them exiting the tray. Is this an old instinct/survival thing? Covering the scent of the pack? They do have 2 other trays, but they completely ignore them and choose to only use this one.