Table 1. Ethogram of observed behaviors.

Category	Behavior	Description
Active	General locomotion	All locomotive behavior performed on the cage lid, climbing up the cage bars by the food hopper to reach the lid, and locomotion on the floor of the cage.
	Rearing	Seen on the floor of the cage with all an animal’s weight on its hind legs and front legs off the ground. Sniffing movements while on its hind legs were commonly accompanied with this behavior.
	Sniffing	Sniffing was also performed against the cage floor (ground), or in between the bars of the cage lid. Slight upward jerks of the head were seen.
Maintenance	Grooming	All grooming behavior including licking the fur, grooming with the forepaws, and scratching with any limb. Grooming was usually performed in a sitting position with the animal’s hind quarters in contact with the floor.
	Feeding or drinking	The animal would rear up to gnaw at food pellets through the bars of the hopper. The forepaws would usually be used to hold the food pellet steady. The animal would rear up and lick the nipple drinker.
Inactive	Sleeping	The animal was motionless, and either lying curled up on its side, or sitting curled up, with its face tucked into its body and out of sight of the camera. Occasionally interrupted by brief single twitches of the body.
	Still and alert	The animal was sitting or curled up, but in contrast to sleep, the face was lifted. The animal either sat motionless, or would appear to be orientating its head to sounds outside of the cage.
	Inactive in nest	The animal within the nest, due to camera angles, cannot clearly be seen but no movement within the nest can be detected. It is assumed that the animal is sleeping within the nest. This is distinguishable from other behaviors within the nest because movement within the nest or of the nest itself is not observed.
Nesting	Pull in	Characterized by the animal reaching out of the nest and pulling sawdust or nesting material to the edge of the nest. The animal may also grasp the material in its mouth and drag it into the nest site. Gathering is distinct from locomotion in that the hind legs do not leave the nest site, and each time the animal reaches out of the nest it pulls its forelegs back in.
	Carrying	Locomotion with material, such as large pieces of bedding or nesting material in the mouth.
	Fraying	The animal uses sideways movement of the forepaws to draw material through the beak. Gnawing movements of the jaw and jerking movements with the head are also seen. As a result the edges of the nesting material are bitten off or large pieces of bedding are split into smaller fibers.
	Push-Dig	The forward pushing and kicking of substrate material with fast alternating movements with the forepaws often combined with forward locomotion.
	Sorting	The deliberate action of placing specific nesting material strips or bedding material into a particular location while sitting within the nest site.
	Digging	Removing, or apparently trying to remove, substrate material from a certain place by series of fast alternating movement of the forepaws, as a consequence of which the material heaps up under the abdomen of the animal.
	Scrape-dig	The series of forepaw movements are alternated by a few hindwards kicking movements of both hind legs simultaneously, through which the heap under the abdomen of the animal is transported further backwards.
	Fluffing	An unseen nesting behavior, due to insufficient camera angles or view from inside the nest, which results in the enlargement of the nest from the inside. Walls of the nest will appear to jump and the nest as a whole will enlarge. It is assumed that the animal is hollowing out the inside of the nest by pushing the walls back and up.
Unknown in Nest	Unknown	An animal is inside of the nest but unsure of the behavior being occurring inside of the nest. This is different from Fluffing in that the nest does not appear to be growing or occurs out of the sequence on nest building. This is also different from Inactive in Nest in that movement is seen within the nest.
Unknown	Unknown	An animal’s behavior cannot be determined or the view of the animal is blocked while in or outside of the nest.