Pneumatic bones can be found in:

$A$: All birds,except the one like Koel (cuckoo),build nests for retiring and taking rest during night time.
$R$: Koel lays eggs in the nests of tailor bird.

Which of the following classes of animals possess a four-chambered heart and nucleated $RBC$s?

Which of the following statements is true for a pigeon ($Columba$ $livia$)?

Which animals have a beak with jaws but no teeth?

Identify the correct statements regarding class $Aves$.
$I$. Forelimbs are modified into wings and hindlimbs are modified for walking and swimming.
$II$. Heart is completely four-chambered.
$III$. They are homeotherms.
$IV$. They are oviparous and development is direct.