Because Comby is frequently out there all by himself! In fact, pretty much every day. The weather has to be awfully awful for him to stay holed up in the condo. Eli, on the other hand, hibernates all winter. At least during the day.
Actually, Eli hibernates all year now that I think about it ;-D. And that's why he hasn't made the card in a few years ;-). He does make almost every night trek out to the barn though, so I'll give him points for that. Maybe I'll paint a night time card some year :-).