Extended Data Table 1. Results of linear models investigating the relationship between the growth of challenged individuals and their fed challengers in juveniles and adults.

The response variable is the growth of the challenged individual, calculated as the individual weight difference between the start and mid-point of the experiment. The juvenile model includes 12 females and 20 males and the value of the model adjusted R² is 0.65. The adult model includes 8 females and 9 males and the value of the model adjusted R² is 0.61. Est.: Estimate, SD: standard deviation.

Variable	Est.	SE	DF	F-value	P-value
JUVENILES
Growth of fed challenger (g)	1.068	0.17	27	39.43	<10-4
Sex	-14.178	8.50	27	2.78	0.107
Age	0.726	0.94	27	0.59	0.448
Rainfall	0.012	0.09	27	0.02	0.897
ADULTS
Growth of fed challenger (g)	0.916	0.24	12	14.72	0.002
Sex	6.143	13.99	12	0.19	0.668
Age	-0.164	0.06	12	7.16	0.020
Rainfall	0.205	0.08	12	7.19	0.020