Bird Species by Average Mass
| Common name | Average mass (kg) | Capable of flight? |
|---|---|---|
| Great bustard | 10.6 | Yes |
| Trumpeter swan | 12.7 | Yes |
| Emperor penguin | 31.5 | No |
| Common ostrich | 104.0 | No |
Most bird species that are capable of flight weigh less than a kilogram (kg), which is not surprising considering the burden that extra body weight puts on a flying animal. But not all flying birds are so light, as we can see most clearly in the example of the __________