Table 2. Dependence of the cross-sectional area of the calamus, or alternatively growth rate by mass, on both feather-length and feather massiveness (mass of feather material per mm feather-length).

	Intercept	95% CI	log(feather-length)		log(feather massiveness)		R2
			Slope	95% CI	Slope	95% CI
Longest primary of 27 species
log(calamus cross-sectional area)	-0.826	-1.749, 0.097	0.676 **	0.261, 1.090	0.723 ***	0.505, 0.940	0.992
log(growth-rate by mass)	0.407	-0.879, 1.693	0.121 --	-0.456, 0.699	1.161 ***	0.858, 1.464	0.988
Remiges of Golden Eagle
log(calamus cross-sectional area)	1.629	0.537, 2.720	0.539 *	0.134, 0.945	0.849 ***	0.463, 1.235	0.94, 0.95
log(growth-rate by mass)	1.520	0.433, 2.607	0.650 **	0.246, 1.053	0.725 ***	0.341, 1.110	0.94, 0.96
Primaries of 6 passerine species
log(calamus cross-sectional area)	-0.359	-0.983, 0.266	0.473 ***	0.200, 0.746	0.901 ***	0.695, 1.106	0.98, 0.99
log(growth-rate by mass)	-1.746	-2.519, -0.973	1.099 ***	0.758, 1.440	0.341 *	0.062, 0.619	0.78, 0.99

Results from linear models for the longest primary of 27 species. Mixed effects models for the remiges of Golden Eagle and the primaries of six passerine species with marginal R² (without the random effect individual) and conditional R² (with the random effect individual). Significance of the slopes

*** P < 0.001

** P = 0.002 or 0.003

* P = 0.01 or 0.02,

^--slope not significantly different from 0.