Table 2.

Standardized regression coefficients (β) and their 95% confidence intervals for linear models relating sex, sine of date, and their interaction with surface areas of the total bill, rhamphotheca, and skeletal bill in Alameda and Belding's sparrows. For sex, female was the reference category

Taxon	Measurement	N	sex (male)	sdt	sex * sdt
Alameda sparrow	Total Bill	366	0.30 (0.21 to 0.39)	−0.54 (−0.65 to −0.42)	0.14 (0.02 to 0.26)
	Rhamphotheca	200	0.49 (0.37 to 0.62)	−0.35 (−0.51 to −0.19)	0.25 (0.08 to 0.41)
	Skeletal Bill	200	0.08 (−0.05 to 0.22)	−0.37 (−0.54 to −0.20)	−0.06 (−0.24 to 0.11)
Belding's sparrow	Total Bill	388	0.51 (0.40 to 0.62)	−0.58 (−0.83 to −0.33)	0.33 (0.08 to 0.59)
	Rhamphotheca	132	0.45 (0.25 to 0.65)	−0.65 (−1.14 to −0.16)	0.52 (0.01 to 1.03)
	Skeletal Bill	132	0.01 (−0.20 to 0.18)	−0.48 (−0.95 to −0.01)	0.00 (−0.49 to 0.49)