Exercise 2 solution

For a 100 g bird:
- Skeleton: about 5% = 5 g
- Skull: about 1% = 1 g (part of the skeleton)
- Pectoral muscles: 15-25% = 15 g to 25 g
- Plumage: two or three times the skeleton = 10 g to 15 g (an estimate that combines two separate statements; treat it as rough)

Note: these are percentages for a typical flighted bird as given in the source; real species vary.