Why can flying birds be so much larger then bats?

Birds can be larger than bats because they have a different body plan that allows them to support their weight in the air.

Birds have a number of adaptations that help them fly, including:

- Wings: Birds have long, strong wings that are covered in feathers. These wings provide lift and allow birds to stay in the air.

- Hollow bones: Birds have hollow bones that are filled with air. These bones are lighter than solid bones, which helps birds to reduce their overall weight.

- Air sacs: Birds have air sacs that help them to breathe while they are flying. These air sacs also help to reduce the bird's overall weight.

- Strong muscles: Birds have strong muscles that help them to flap their wings and stay in the air.

Bats, on the other hand, are mammals that have adapted to fly. They have a number of adaptations that help them fly, including:

- Wings: Bats have wings that are made of skin and bone. These wings are not as strong as bird wings, but they are still strong enough to allow bats to fly.

- Small size: Bats are relatively small animals, which helps them to reduce their overall weight.

- Agile bodies: Bats have agile bodies that allow them to maneuver in the air.

The combination of these adaptations allows birds to fly and reach larger sizes than bats.