Correlation between body mass and ontogenesis length (sum of the duration of incubation and nestling periods). Corvids are marked in red. Numbers denote family: 1 – Acrocephalidae, 2 – Alaudidae, 3 – Calcariidae, 4 – Certhiidae, 5 – Cinclidae, 6 – Corvidae, 7 – Emberizidae, 8 – Fringillidae, 9 – Hirundinidae, 10 – Laniidae, 11 – Locustellidae, 12 – Motacillidae, 13 – Muscicapidae, 14 – Oriolidae, 15 – Paridae, 16 – Passeridae, 17 – Prunellidae, 18 – Sittidae, 19 – Sturnidae, 20 – Sylviidae, 21 – Troglodytidae, 22 – Turdidae.