Apart from mammals,which other group of animals maintains a high and constant body temperature?

$S$ - Statement: In ostriches,the aortic arch turns to the left.
$R$ - Reason: In kangaroos,the aortic arch turns to the right.

In which of the following animals,the digestive tract has additional chambers like crop and gizzard?

What is the primary function of pneumatic bones in birds?

The vertebrae in birds are mostly

Which of the following is a characteristic feature of $Aves$?