Spatial variation in avian bill size is associated with humidity in summer among Australian passerines

Table 4 Full output of Model 3: best model of factors affecting bill surface area

	Wald statistic	Df	p-value	parameter	SE
(Intercept)	500.722	1	<0.001	5.650	0.56786
Wing length	636.932	1	<0.001	0.011	0.000568
SeasonCapture.autumn	51.499	3	<0.001	.	.
.winter				−0.010	0.005387
.summer				0.031	0.007547
.spring				0.013	0.005351
Sex (male relative to female)	60.443	1	<0.001	0.031	0.004217
YearCapture (continuous)	11.150	1	0.001	−0.00091	0.00027
Humidity	26.335	1	<0.001	0.0160	0.00544
Tmax	0.338	1	0.561	0.00587	0.00274
Humidity.Tmax	4.277	1	0.039	−0.0003467	0.000168
Variance/covariance of random effects	Component	SE
Region	0.000446	0.000142
YearCapture	0.000166	0.000082
Species:Phylo	0.108706	0.070089
Species:NonPhylo	0.053945	0.017836
cov(SpeciesNonPhylo,SpNonPhylo:Humidity)	0.001227	0.001389
SpNonPhylo:Humidity	0.000480	0.000211
Residual	0.008343	0.000227

Results are from a full mixed model of bill size (log-transformed) with fixed effects of body size (wing length), season of capture, sex, humidity, Tmax and the interaction between humidity and Tmax. The table shows Wald statistics, df, p-values, parameter estimates and standard errors (SE). Significant weather terms (p < 0.05) are shown in bold. The random effects were region, year of capture (multi-level factor), phylogenetic species effect (SpeciesPhylo), a non-phylogenetic species effect (SpeciesNonPhylo), and an effect of humidity for each species (not linked to the phylogeny; SpNonPhylo:Humidity); see further details of Model 3 in Methods. The table shows the variance components for each random effect (and SE), and also the covariance between the intercepts and slope for the non-phylogenetic species effect, which was also fitted. Parameter estimates for Season of Capture are relative to autumn, and for Sex are for males relative to females. N = 2864 individuals; 36 species; 41 years; 77 IBRA Regions. Log-likelihood of model = 5187.482

ISSN: 2053-7565