Maximum peck and pull forces exerted by Jungle and Carrion Crows

We investigated whether there are significant differences in neck muscle mass, maximum peck force, pressure and maximum pull force between Jungle Crows Corvus macrorhynchos and Carrion Crows C. corone. The maximum peck force and pressure were measured using pressure sensitive film. The maximum pull force was measured with spring balances. For male Jungle Crows, neck muscle mass, maximum peck force, pressure and maximum pull force were 8.27 g, 26.8 N, 80.4 MPa and 9.54 N; for females they were 6.82 g, 22.3 N, 69.7 MPa and 8.25 N. Those values for male Carrion Crows were 6.69 g, 22.3 N, 59.7 MPa and 4.07 N;, whereas for females they were 4.50 g, 15.1 N, 53.2 MPa and 2.71 N. Furthermore, neck muscle mass, maximum peck force and maximum pull force were positively correlated with body mass in both species. There were no significant differences in the ratio between the cervical levator mass and the cervical depressor mass, and the maximum peck force exerted by one unit of the cervical depressor mass between Jungle and Carrion Crows. However, the maximum pull force exerted by one unit of the cervical lavator and depressor mass of Jungle Crows was significantly larger than that of Carrion Crows.