Table 1.

Nestlings’ likelihood of performing body movements, according to their own vocal behavior, food treatment, and characteristics and the vocal behavior and food treatment of their nestmate (live partner or playback). Three settings are analyzed: (a) nestling pairs in their natural nest, (b) nestling pairs in the laboratory, and (c) singleton nestlings responding to a playback. Result of generalized linear models. Superscript numbers indicate quadratic terms (see main text).

	a. Nestling Pairs in the Field (Experiment 1) d.f. = 417			b. Nestling Pairs in the Lab (Experiment 2) d.f. = 12,251			c. Playback (Experiment 3) d.f. = 4372
Effects	F	p	Estimate	F	p	Estimate	F	p	Estimate
Partner body movements	12.9	0.0004	1.106 ± 0.308	11.1	0.0009	0.523 ± 0.157	-	-	-
Call rate	15.2	0.0001	0.126 ± 0.032	3.5	0.061	−0.038 ± 0.02	272.1	<0.0001	0.561 ± 0.034
Call rate 2	0.9	0.34	0.004 ± 0.004	6.7	0.009	0.003 ± 0.001	83.2	<0.0001	−0.024 ± 0.003
Partner/Playback call rate	15.0	0.0001	0.276 ± 0.071	124.9	<0.0001	0.118 ± 0.011	4.4	0.037	0.058 ± 0.028
Partner/Playback call rate 2	6.2	0.013	−0.008 ± 0.003	1.7	0.19	0.001 ± 0.001	5.4	0.019	0.003 ± 0.001
Sex (male vs. female)	1.0	0.31	−0.773 ± 0.767	0.2	0.67	0.114 ± 0.267	5.2	0.022	0.483 ± 0.211
Age	0.4	0.56	0.039 ± 0.067	0.7	0.41	−0.023 ± 0.029	0.7	0.40	0.024 ± 0.028
Seniority (junior vs. senior)	1.1	0.30	0.786 ± 0.758	1.0	0.31	0.303 ± 0.3	-	-	-
Food treatment (food-deprived vs. satiated)	0.0	0.99	−0.005 ± 0.775	0.0	0.93	−0.009 ± 0.103	-	-	-
Partner food treatment (food-deprived vs. satiated)	0.0	0.92	0.078 ± 0.735	-	-	-	-	-	-
Time (min)	0.2	0.67	−0.013 ± 0.031	10.5	0.001	−0.004 ± 0.001	157.6	<0.0001	−0.018 ± 0.001
				d.f. = 7024			d.f. = 1653
Call duration	-	-	-	11.2	0.0008	−6.5 ± 2.3	22.7	<0.0001	−11.0 ± 2.3
Call duration 2	-	-	-	6.0	0.014	−5.3 ± 1.6	13.5	0.0003	4.9 ± 1.3
				d.f. = 7068			d.f. = 4312
Partner/Playback call duration	-	-	-	50.0	<0.0001	−12.3 ± 1.7	0.7	0.41	2.6 ± 3.1
Partner/Playback call duration 2	-	-	-	12.0	0.0005	3.9 ± 1.1	4.6	0.031	−4.1 ± 1.9