Question

Why is the bat included under mammals?

Answer 1

Hint: Mammals have characteristics that they possess mammary glands in milk producing glands. Mammals include humans and all other warm blooded animals or vertebrates having back-bones.

Complete answer
Bats are common flying mammals that belong to the taxonomic order chiroptera. More than 1400 species of bats are known.
Bats are included under mammals because the most unique mammalian characteristic is the presence of milk producing glands (mammary glands) by which they nourish the young ones they have two paws of limbs adapted for flying.
Bats are winged mammals, and technically the only winged mammals.
Also bats are warm-blooded vertebrates.
Bats also possess body hair, their inner ear bones, neocortex and a jaw hinged directly to the skull.
Thus bats are mammals as they give birth to their young ones instead of laying eggs as in birds, also they have mammary glands to nourish young ones and have hairs.

Additional Information: Bats do not flap their entire forelimbs, like birds but, but instead flap their spread out digits which are very long and covered with a thin membrane or patagium. Bat winged are thinner than those of birds.

Note:Bats belongs to order chiroptera. They are nocturnal animals. The flight organs are called patagia. The sense of touch and hearing are remarkably developed. They produce supersonic sounds, which are reflected from the objects in their way and the echoes are perceived by their ears. Bats have mammary glands and they give birth to young ones. Observe bat wings when they fly.