Table 2.

Results of linear mixed effects models using factor scores from the first two principal components of PCA to test for differences in uropygial gland microbiota among free-living and captive song sparrows, using bird ID as a random effect to account for birds that were sampled twice: an initial (free-living) sample collected on the day of capture and a captive sample collected after approx. 11 months in captivity (see Table S3 for factor loadings).

	Estimate	SE	t	F	p
PC1
Fixed effects
Intercept	− 6.3	0.9	− 7.1	–	–
State (free-living, captive)	13.1	1.2	10.6	113.3	< 0.0001

	Variance	SD
PC1
Random effects
Bird ID	2.8	1.7
Residuals	25.9	5.1

	Estimate	SE	t	F	p
PC2
Fixed effects
Intercept	2.4	0.7	3.3	–	–
State (free-living, captive)	− 5.1	1.1	− 4.7	22.1	< 0.0001

	Variance	SD
PC2
Random effects
Bird ID	0.0	0.0
Residuals	20.8	4.6