Where does this come from, and can I check it?

Internal braces keep them stiff while saving weight for flight. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a animals fact?

Yes. It sits on the Animals shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

Many bird bones are hollow and strutted

Internal braces keep them stiff while saving weight for flight The bones connect to air sacs in the respiratory system, so they carry air rather than marrow. That reduces density without losing strength. Bird skeletons are also fused in places, such as the wishbone and the pelvis, for rigidity. It sits in Mondo's animals collection, one of 200 facts that each trace back to the reference below.

Where this comes from

Britannica

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Science trivia

More facts like this

Wandering albatrosses can fly thousands of miles without flappingAlbatrosses exploit ocean wind shear gradients using dynamic soaring.Common swifts can stay airborne for ten months continuouslySwifts feed, mate, and sleep in mid-air without landing on ground.Sharks have cartilage instead of boneTheir skeletons are lighter and more flexible than bone would be A giraffe neck has seven bones, like yoursEach vertebra is simply stretched to about 25 centimetres Alpine swifts can stay airborne for over 200 daysTracking showed the birds never landed during their African winter A bat's wing is skin stretched over fingersThe finger bones are elongated and the membrane between them is flexible leather

Tags: birds, skeleton, flight

Many bird bones are hollow and strutted: the short answers

Where does this come from, and can I check it?: Internal braces keep them stiff while saving weight for flight. The figure is taken from Britannica, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a animals fact?: Yes. It sits on the Animals shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.