Well the description says:
It doesn’t matter if it is a domestic animal or wild animal. Furless animals and kangaroos are acceptable as well.
So I’d have to think birds and seals should work too…
But with the title “on all fours”, well…is there a line somewhere? Seals don’t have legs that they stand on. Birds are borderline; do wings count?
The only person who could really say is Cuddlebutt/ScreamingInDigital who was the originator of this contest a year and some months ago.