1. Hummingbirds glue their tiny nests together with spiderwebs! A hummingbird nest is no bigger than a walnut shell. They weave plant down and moss together using sticky spider silk, which allows the nest to stretch bigger as the baby birds grow.

2. Nests aren't just for birds. Many different animals build nests! Squirrels weave leafy tree nests called dreads, orangutans build fresh sleeping platforms in trees every single night, and alligators build giant mounds of mud and plants on the ground.

3. Eagles build nests as big as a room. Bald eagles reuse the same nest year after year, adding new sticks every spring. The largest recorded bird nest was built by bald eagles in Florida—it measured 10 feet wide, 20 feet deep, and weighed nearly 3 tons (as heavy as two cars)!

4. Edible bird nests are made entirely of spit. Swiftlets, tiny birds living in Southeast Asian caves, build nests using only their own hardened, sticky saliva. People harvest these nests to make a famous delicacy called "bird's nest soup!"

5. Weaver birds build entire apartment buildings. Social weavers in southern Africa work together to construct massive communal nests in trees or on telephone poles. These giant structures can house over 100 pairs of birds in separate "rooms" under one roof!

6. Termite nests can be taller than two-story houses. Compass termites in Australia construct massive mud mounds up to 15 feet tall. These super-structures have built-in air conditioning systems with ventilation shafts to keep the underground colony cool!

7. Hornbill moms lock themselves inside their nests. When a female hornbill is ready to lay eggs in a tree hollow, she and her mate plaster the entrance closed with mud, leaving only a tiny slit. The male feeds her through the slot for weeks until the babies are ready to fly out!