Table 2.

General linear mixed models (Gaussian distribution) showing that variation in the extent of white in the tail (TWIndex) has no significant linear or curvilinear effect on either lifetime reproductive performance (a) or breeding-season body mass (b) in hooded warblers. (Initial year present on the study site was included in both models as a random effect. Marginal and conditional R² and the intraclass correlation coefficient (ICC) for the random effect are shown for each model. Models were calculated using the Mixed Model personality of the Fit Model platform of JMP Pro 17.0 (SAS Institute Inc., Cary, North Carolina, 2023).)

model term	estimate	s.e.	denominator d.f.	t	p-value
(a) total young fledged: marginal R2 = 0.603, conditional R2 = 0.618, ICC = 0.038
intercept	–1.57	1.25	608.6	–1.26	0.21
sex	0.19	0.14	616.9	1.43	0.15
n years present	2.68	0.09	612.9	30.14	<0.0001
TWIndex	1.68	2.32	614.6	0.72	0.47
TWIndex2	37.06	32.48	615.4	1.14	0.25
TWIndex × sex	–0.94	2.30	608.7	–0.41	0.68
TWIndex2 × sex	41.59	32.49	616.1	1.33	0.20
(b) body mass: marginal R2 = 0.206, conditional R2 = 0.229, ICC = 0.029
intercept	7.33	1.26	444.9	5.81	<0.0001
sex	0.44	0.05	445.0	8.73	<0.0001
wing chord	0.067	0.018	444.4	3.60	0.0004
TWIndex	–0.21	0.67	440.8	–0.31	0.47
TWIndex2	12.67	9.37	443.1	1.35	0.18
TWIndex × sex	0.48	0.67	440.4	0.72	0.48
TWIndex2 × sex	–2.02	9.32	443.1	–0.22	0.82