3.2 | The body condition change pattern in winter
Based on the validation test of body condition indices, body mass
(R2 = 0.5925, p-value < 0.05), fat score
(R2 = 0.7206, p-value < 0.01), and the ratio
of body mass/ bill + tarsus length (R2 = 0.8299,
p-value < 0.001) were finally chosen as dependent variables
for further analysis (detailed information
in
supplementary material table S1).
The regression analysis of the ordinal day effect on the body condition
indices showed that both body mass (β = 0.011 ± 0.004, p <
0.01) and fat score (β = 0.012±0.004, p < 0.01) had
significant positive regression on the ordinal day (Figure. 2A-2B).
However, the ordinal day showed a slightly positive effect on the body
mass ratio (β = 0.0002 ± 0.0001, p = 0.0897). The comparison test of
body condition indices among different winter stages showed that only
fat score had a significant variance among different winter stages. Fat
score was typically higher in late winter as compared to pre-winter (p =
0.0028) and early winter (p = 0.0079) based on the Kruskal-Wallis test
(Figure. 2C). However, the ANOVA-test of body mass and body mass ratio
in any paired winter stage group showed no significant differences.