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

Table 4 The results of linear regression of fuel load (M_f, Eq. 2) against year by species, including change (∆) between 1964 and 2020 and mean M_f for those which showed no significant change

Species	Gradient (m)	Intercept (b)	Adjusted R²	Standard error of residuals	F	P	Mean M_f (%)	Δ M_f (%)
*A. pratensis*	-0.028	72.94	< 0.01	8.88	0.75	0.39	16.30	-0.67
E. rubecula*	-0.104	221.20	0.01	4.45	14.04	< 0.01		-5.83
*O. oenanthe*	0.211	-407.76	0.05	14.11	3.34	0.07	12.33	11.80
*P. collybita*	-0.108	230.94	< 0.01	9.35	12.10	< 0.01		-6.06
*P. modularis*	-0.153	318.73	0.07	9.38	67.26	< 0.01		-8.57
*P. phoenicurus*	0.047	-84.16	< 0.01	10.51	1.28	0.26	9.65	2.65
P. trochilus*	-0.081	135.81	0.04	3.56	63.31	< 0.01		-8.12
S. atricapilla*	0.001	12.01	< 0.01	4.87	0.00	0.95	14.79	0.08
S. borin*	0.010	-6.68	< 0.01	4.77	0.06	0.82	13.95	0.58
*C. communis*	0.043	-70.63	< 0.01	0.14	5.49	< 0.05		2.40
*S. vulgaris*	-0.035	74.62	< 0.01	6.51	0.82	0.37	5.19	-1.95
T. iliacus*	-0.140	289.47	0.02872	4.74	24.21	< 0.01		-7.84
*T. merula*	-0.163	332.99	0.09	8.60	381.60	< 0.01		-9.12
*T. philomelos*	-0.257	528.30	0.19	9.29	128.10	< 0.01		-14.37
T. troglodytes*	-0.250	509.40	0.1438	4.14	99.23	< 0.01		-14.00

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

ISSN: 2051-3933