Table 8.

Mean proportions of individuals gnawing on the tunnel walls depending on the substrate exposition and the tunnel considered.

Tunnel	Substrate	Mean proportion of individuals gnawing on the walls ± SE	Size effect compared to each tunnel without substrate	Mean number of individuals gnawing on the walls ± SE	Size effect compared to each tunnel without substrate
Narrow	None	0.44 ± 0.1	0	2.58 ± 0.07	0.00
	Excavator	0.36 ± 0.03	0.27	1.01 ± 0.07	1.05
	Desert Bedding-Atacama	0.33 ± 0.02	0.38	0.80 ± 0.06	1.27
Wide	None	0.011 ± 0.004	0	0.033 ± 0.008	0.0
	Excavator	0.04 ± 0.01	0.26	0.05 ± 0.02	0.26
	Desert Bedding-Atacama	0.06 ± 0.004	0.03	0.02 ± 0.01	0.03
Narrow vs wide			2.3		2.17