Diurnal variation in corticosterone release among wild tropical forest birds

Table 1 Baseline corticosterone (y₁), “increase in corticosterone” (y₂) and “stress-induced corticosterone” (y₃) models selected from AIC_c analyses

	Response Variable	Linear Formula (Intercept and Variable Coefficients)							ω_i
	Response Variable	Int.	Time	Date	Molt	Hemo.	R. Mass	Lat.	ω_i
Total	y₁	+1.871 [+1.697, +2.046]	−0.236 [−0.388, −0.086]	---	−0.325 [−0.631, −0.016]	---		+0.296 [+0.150, +0.444]	0.29
Total	y₃	+4.130 [+3.976, +4.283]	---	---	−0.310 [−0.575, −0.048]	---	---	n/a	0.19
Males	y₁	+2.179 [+1.846, +2.514]	−0.312 [−0.549, −0.075]	+0.377 [+0.095, +0.646]	−0.714 [−1.324, −0.104]	---	---	+0.278 [+0.026, +0.525]	0.26
	y₂	+4.303 [+3.963, +4.640]	---	+0.376 [+0.076, +0.676]	−0.838 [−1.436, −0.259]	---	---	---	0.24
	y₃	+4.396 [+4.087, +4.716]	---	+0.378 [+0.094, +0.665]	−0.757 [−1.319, −0.208]	---	---	n/a	0.36
Females	y₁ ^a	+1.838 [+1.491, +2.198]	−0.356 [−0.641, −0.064]	---	−0.661 [−1.204, −0.108]	---	---	---	0.09
G. spirurus	y₁	+1.952 [+1.591, +2.312]	−0.667 [−1.110, −0.219]	---	---	−0.713 [−1.187, −0.235]	---	---	0.36
G. spirurus	y₃	+3.525 [+3.171, +3.863]	---	−0.439 [−0.842, −0.042]	---	---	---	n/a	0.21
M. olivaceus	y₂	+4.510 [+4.218, +4.805]	---	---	---	---	+0.366 [+0.057, +0.682]	---	0.51
M. olivaceus	y₃	+4.601 [+4.318, +4.885]	---	---	---	---	+0.346 [+0.048, +0.639]	n/a	0.54

Models are listed with formula and Akaike weight (ω_i). Coefficient of determination, degrees of freedom and F-ratios are given in the main text. Credible intervals (in square brackets) of all predictor coefficients in these selected models do not overlap zero. This selection criterion was not met by other models within 2 AIC_c of top-ranked models (see Additional file 1: Table S1). Corticosterone response variables (ng/ml) are log-transformed to base e. Models are given for total and sex-partitioned interspecific corticosterone variation as well as for intraspecific analyses of the wedge-billed woodcreeper (G. spirurus) and olive-striped flycatcher (M. olivaceus). Abbreviated candidate variables are sampling time of day, sampling date, molt status, hemoglobin concentration, relative body mass and sampling latency. Interspecific analyses employ body mass : tarsus ratio as the relative mass variable, whereas intraspecific analyses employ a scaled mass index. ^a ∆AIC_c = 0.060 (all other models listed in this table ranked first in AIC_c analyses)

ISSN: 1742-9994