# Birds
Confidence: high
Last verified: 2026-05-22
Generation: ai_assisted


## TL;DR

Birds (class Aves) are feathered, warm-blooded vertebrates descended from theropod dinosaurs. ~11,000 species. Key adaptations: feathers (flight + insulation), hollow bones (lightweight), beak (no teeth, lightweight), highly efficient respiratory system, wings (modified forelimbs). Migration: Arctic Tern — 90,000 km annually (longest migration).

## Core Explanation

Flight mechanics: lift from wing shape (airfoil), thrust from flapping. Songbirds (passerines): 60% of bird species. Raptors: eagles, hawks, falcons — hooked beak, talons, exceptional vision. Penguins: flightless, 'fly' underwater. Hummingbirds: can hover, fly backwards, 80 wingbeats/second. Owl: silent flight (specialized feathers), rotating head 270°. Bird intelligence: crows use tools, recognize faces — corvids are among the smartest non-human animals.

## Further Reading

- [The Sibley Guide to Birds (2nd Ed)](https://www.penguinrandomhouse.com/books/232944/the-sibley-guide-to-birds-second-edition-by-david-allen-sibley/)