Fig. 3. The dependence of basal metabolic rates (BMR), mass-specific basal metabolic rate (BMR_w), and lifetime expenditure of energy (LxBMR_w) on body mass (M) in songbirds (oscines) is different from that of all other birds. The oscines birds genera are indicated by open circles, and all other bird genera are indicated by solid circles; the oscines family Fringillidae (true finches) genera are indicated by inverted triangles. The regression lines for the whole Neognathae clade (N=123) are solid, the lines for all other birds (N=64) are dotted, the oscine birds lines (N=59) are dash–dot–dash, and the Fringillidae lines (N=28) are dash–dot–dot–dash. If the regression was not significant the line was omitted. (A) lnBMR as a function of lnM. For the whole clade, lnBMR=3.765+0.648xlnM (r²=0.966, P<0.001). For oscine birds, lnBMR=3.577+0.735xlnM (r²=0.934, P<0.001). For Fringillidae, lnBMR=3.167+0.857xlnM (r²=0.920, P<0.001); and for all other birds, lnBMR=3.519+0.678xlnM (r²=0.966, P<0.001). The slopes of the three curves were significantly different from each other. (B) lnBMR_w as a function of lnM. For the whole clade, lnBMR_w=3.765–0.352xlnM (r²=0.893, P<0.001). For oscines, lnBMR_w=3.577–0.256xlnM (r²=0.648, P<0.001). For Fringillidae, lnBMR_w=3.167–0.143xlnM (r²=0.243, P=0.008). For all other birds, lnBMR_w=3.519–0.322xlnM (r²=0.866, P<0.001). The difference in slopes between oscines, –0.256±0.026, and all birds, –0.352±0.011, is highly significant (t=3.13, P=0.001), but the difference in intercept is not significant. (C) ln(LxBMR_w) as a function of lnM. For the whole clade, ln(LxBMR_w)=5.495–0.155xlnM (r²=0.323, P<0.001). For oscines, ln(LxBMR_w)=5.136–0.0139xlnM (r²=0.001, P=0.805). For Fringillidae, ln(LxBMR_w)=4.411+0.212xlnM (r²=0.066, P=0.188); and for all other birds: ln(LxBMR_w)=5.317–0.136xlnM (r²=0.245, P<0.001). The average value of ln(LxBMR_w) was significantly larger for oscines birds, 5.093±0.368, than that of all other birds 4.567±0.562 (t=6.082, P<0.001).