Table 1. Reduced major axis regressions between feather growth-rate by mass, and alternatively feather growth-rate by length, and the cross-sectional area of the calamus as a proxy of feather follicle size.

	Intercept	95% CI	Slope	95% CI	R2
Longest primary of 27 species
log(growth-rate by mass) ~ log(calamus cross-sectional area)	2.901	2.866, 2.935	1.142*	1.078, 1.211	0.981
log(growth-rate by length) ~ log(calamus cross-sectional area)	0.523	0.491, 0.549	0.236	0.185, 0.297	0.755
Remiges of Golden Eagle
log(growth-rate by mass) ~ log(calamus cross-sectional area)	0.253	0.141, 0.356	0.971--	0.898, 1.049	0.941
log(growth-rate by length) ~ log(calamus cross-sectional area)	-0.590	-0.726, -0.481	0.316	0.24, 0.411	0.572
Primaries of 6 passerine species
log(growth-rate by mass) ~ log(calamus cross-sectional area)	-0.116	-0.129, -0.104	1.046--	0.929, 1.181	0.842
log(growth-rate by length) ~ log(calamus cross-sectional area)	0.471	0.443, 0.487	0.229	0.057, 0.487	0.096

Intercept and slope (scaling exponent) are given with their 95% confidence intervals (95% CI). For growth-rate by mass:

* = slope is significantly different (P < 0.001) from 1;

^-- = slope not significantly different from 1 (P > 0.32).