Table 4. GLMM predicted effects of supplementary feeding treatment, age, brood size and environmental variables on nestling mass in reed warblers.

Parameter	Estimate ± SE	F	P
Treatment (Fed)	0.14 ± 0.13	41.21	<0.0001
Brood size	-0.52 ± 0.09	35.93	<0.0001
Nestling Age	2.90 ± 0.10	1520.74	<0.0001
Site	-0.30 ± 0.08	42.46	<0.0001
Invertebrate availability	-0.004 ± 0.001	9.62	0.0028
Treatment × Nestling age	0.50 ± 0.16	6.79	0.0112