TABLE 1.

Comparison between generalized linear models built to explain the counts of surface episodes every 3 h in summer and winter, using different combinations of the environmental measures.

Summer
Fixed effect variables	AIC	X 2	R2 (%)
Hour+Tsur	3901.2	61.2	55.9
Hour+Tsur+Tsoil	3906.4	61.3	55.9
Tsur+Hour*Tsoil	3906.6	76.1	56.9
Hour*Tsur+Tsoil	3909.3	67.9	56.2
Hour*Tsur+Hour*Tsoil	3911.6	79.1	56.9
Hour+Tsoil	3929.5	34.0	53.6
Hour	3935.5	22.4	52.4
Winter
Fixed effect variables	AIC	X 2	R2 (%)
Hour*Tsoil+Tsur	1517.7	42.2	45.9
Hour+Tsoil+Tsur	1518.2	34.8	42.6
Hour+Tsur	1518.7	30.0	42.7
Hour*Tsur+Hour*Tsoil	1519.0	45.2	47.6
Hour	1522.4	22.5	41.9
Hour*Tsoil	1522.6	33.1	49.9
Hour*Tsur+Tsoil	1523.0	34.9	42.4
Hour+Tsoil	1523.6	25.4	46.1
Tsoil	1532.1	7.7	45.4
Tsur+Tsoil	1534.2	11.6	44.8
Tsur	1539.5	2.2	34.7

Asterisks represent interaction effect between variables. Models with interactions included the corresponding isolated terms. The final model (bold values) was chosen by lowest AIC (Akaike Information Criterion, see section “ Materials and Methods ” ). X² - values were calculated against the null model. R² - values account for the random structure. Datasets had 973 observations and 12 animals for summer and 227 observations and 9 animals for winter.