Differential changes in the morphology and fuel loads of obligatory and partial migrant passerines over half a century in Britain

Table 2 The results of linear regression of body mass (M_b) against year by species, including changes between 1964 and 2020 and mean M_b for those which showed no significant change

Species	Gradient (m)	Intercept (b)	Adjusted R²	Standard error of residuals	F	P	Mean M_b (g)	Δ M_b (%)
*A. pratensis*	< 0.001	18.15	0.00	1.39	0.00	0.99	17.87	-0.06
*E. rubecula*	-0.016	49.19	< 0.01	1.69	15.75	< 0.01		-5.20
*O. oenanthe*	0.113	-198.17	0.21	3.77	13.98	< 0.01		27.38
*P. collybita*	-0.007	20.80	0.00	0.78	6.64	0.01		-4.53
*P. modularis*	-0.017	54.16	0.03	1.72	26.1	< 0.01		-4.43
*P. phoenicurus*	0.005	4.57	< 0.01	1.37	0.83	0.36	14.36	1.94
P. trochilus*	-0.007	23.04	0.02	1.288	25.32	< 0.01		-4.34
S. atricapilla*	0.004	11.90	< 0.01	2.01	0.79	0.37	18.95	1.05
S. borin*	0.002	14.92	< 0.01	1.94	0.08	0.7788	18.84	0.58
C. communis*	0.009	-2.62	< 0.01	1.79	13.41	< 0.01		3.37
*S. vulgaris*	0.009	61.41	< 0.01	4.19	0.11	0.75	79.42	0.64
T. iliacus*	-0.060	180.34	0.02	3.41	14.16	< 0.01		-5.28
*T. merula*	-0.136	368.08	0.08	8.07	312.30	< 0.01		-7.64
*T. philomelos*	-0.140	352.11	0.15	5.89	100.50	< 0.01		-10.24
T. troglodytes*	-0.020	48.89	0.10	1.323	66.74	< 0.01		-11.04

* Species where regressions were conducted using robust standard errors due to heteroscedasticity

ISSN: 2051-3933