Haematocrit, eggshell colouration and sexual signaling in the European starling (Sturnus vulgaris)

BMC Ecology

Table 3 Associations between eggshell colour and reproductive performance in replacement clutches

Trait	Df	Mean BGC		Treatment
Trait	Df	F	P	F	P
Interval between treatment and day first egg of replacement clutch (days)	1,25	0.00	0.96	5.53	0.03
Mean egg mass	1,25	0.38	0.54	3.26	0.08
Clutch size	1,25	1.23	0.28	1.91	0.18
Female body mass at clutch completion	1,25	0.63	0.43	0.97	0.33
Brood size at hatch	1,25	0.33	0.57	0.24	0.63
Hatchling mass^a	1,24	0.30	0.59	3.22	0.09
Maternal provisioning (nest visits per chick)	1,23	0.63	0.44	4.58	0.04
Paternal provisioning (nest visits per chick)	1,23	0.55	0.46	0.25	0.62
Total provisioning (nest visits per chick)	1,23	0.59	0.45	2.04	0.17
Hct of 17 day old chicks^a	1,20	1.56	0.23	8.90	0.01
Hb of 17 day old chicks^a	1,20	5.83	0.03	1.17	0.29
Mean tarsus length of 17 day old chicks^a	1,23	4.55	0.04	0.40	0.53
Mean mass of 17 day old chicks¹	1,23	1.18	0.29	1.15	0.29
Brood size at fledging	1,25	0.81	0.38	0.10	0.75

Results are from general linear models. Although 29 females produced a replacement clutch, eggshells were not recovered from one replacement clutch and so sample sizes are 28 for all traits except provisioning, for which they are 26. Initial analyses included the eggshell colour * treatment interaction, but in no case was this significant (Additional file 3: Table S3), and it was therefore removed
^aRepeated measures analysis with female identity included as a repeated subject effect. The analysis of hatchling mass included first clutch egg mass as a covariate (F_1,24 = 76.61, P < 0.0001) since eggs were larger pre-treatment in the PHZ group

ISSN: 1472-6785