1
When males and females have very different physical appearances they are called sexually...
2
In terms of embryo development, birds are ...
3
They don´t have teeth in their mouths.
4
Bird bones are ...
5
A bird´s body is covered in ...
6
...help maintain high levels of oxygen-rich air in the respiratory system.
7
Birds have very developed ...to see in the dark.
8
Birds breathe using ...
9
A bird´s upper limbs are...
10
Birds have a mouth with a corneous...
