Table 1.

Allometric relationships between parent mass (M, g) and the thermal properties and dimensions of avian cup-shaped nests according to y = aMb. Statistics include the intercept of the regression mean (a) and scaling exponent (slope, b) according to the allometric relationship y = aMb, as well as the correlation coefficient (r2) and F-ratio. The intercept and scaling exponent values represent the mean ± 95% CI for all species. n = 36 and d.f. = 1,34 for all comparisons, except nest mass which has n = 27 and d.f. = 1,25. The replicate for the nest mass measurements is lower as some nests were excluded from analysis owing to the attachment of supporting branches.

intercept, ascaling exponent, br2F-ratio
internal diameter (dI, cm)2.03 ± 1.090.35 ± 0.020.96865.23a
external diameter (dE, cm)2.35 ± 1.180.42 ± 0.040.91352.99a
internal height (hI, cm)1.74 ± 1.240.26 ± 0.060.7078.85a
external height (hE, cm)2.05 ± 1.340.32 ± 0.080.6665.12a
thickness (X, cm)0.30 ± 1.640.49 ± 0.140.6153.24a
nest mass (MN, g)0.17 ± 3.771.36 ± 0.390.6751.09a
surface area (A, cm2)11.65 ± 1.290.68 ± 0.070.92394.33a
total nest conductance (G, mW °C−1)43.98 ± 1.310.25 ± 0.080.5744.59a
surface-specific nest conductance (GA, W °C−1 m−2)37.74 ± 1.42−0.44 ± 0.100.7181.44a
thermal conductivity (k, mW °C−1 m−1)111.61 ± 1.500.06 ± 0.110.031.09
  • aIndicates that there is a significant effect of parent mass on the variable (p < 0.0001 at α = 0.05) in all cases with exception to thermal conductivity which was not significantly related to mass (p = 0.30).