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There are a number of bird species that construct pretty cool things - today on SciShow, we'll visit with three of them...

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Hank Green: Could I interest you in a condominium? I know one -- it's available right now. Over 100 units, one of the most efficient heating and cooling systems you can find, not to mention an ingenious security system to keep out the riffraff. There's one catch, though. You, uh, you have to be a bird. A sociable weaver, to be specific. One of the more aptly-named creatures in the animal kingdom, and the architect of one of the coolest structures you'll ever see built by a bird.

Found mostly in the Kalahari desert of southern Africa, these birds build communal nests that look like giant enormous haystacks in trees, and in some cases on telephone poles. The largest have dimensions in excess of six meters, with up to 100 nesting chambers. In breeding season, that could mean up to 400 birds in one nest complex.

The weavers use large twigs to construct the roof, and dry grasses as insulation, with green grass to keep the eggs from falling out. Thanks to the nest's sturdy and ingenious construction, they also retain heat extremely well. Scientists have found that even when the outside temperatures fell from 17°C to 0, the internal temperature of the chambers never fell below 16°. And amazingly enough, some sociable weaver nests have been continuously occupied for over 100 years.

But my favorite part of these nests are the sharp spikes of straw that are strategically placed throughout the tunnels, intended to ward off predators like snakes. Researchers report that reaching into one of these things is a painful endeavor.

A lot of nest architecture is about deterring predators, and Montezuma oropendolas in Central America have come up with some innovative ways of keeping their eggs safe too. You can't miss their pendulous basket nests, especially since they tend to be grouped in colonies of 20 or more in a single tree. The females use vines and other plant fibers to weave the nests, a process that takes about two weeks. The final product is anywhere from 60 to 180 cm long, and is usually suspended from a flimsy branch tip. This deters the pesky egg-eating monkeys, as does the location of the tree; oropendolas prefer isolated trees for their nests since monkeys don't like to be out in the open for very long. Oropendolas also tend to build their nests in trees occupied by hornets and wasps. Being so close to stinging insects keeps both predators and parasitic insects at bay.

Finally, we'd need multiple episodes to cover everything that is strange and fascinating about the bowerbird, but here let's just focus on the bowers, the constructions they create. They're not nests, but rather a way to attract the ladies. Of the more than 15 species of bowerbirds in New Guinea and Australia, every adult male will construct one of these in his lifetime.

Designs vary from species to species, but most bowers are constructed using twigs, leaves, and moss, and then decorated with pretty much anything colorful or shiny they can find. Decorations scattered around the bower can include feathers, pebbles, and shells, as well as human litter. Some species will even paint the walls using chewed berries or charcoal. The goal is to lure the female inside, which is where the mating takes place, but competition is fierce and it's not uncommon for younger males to find their bower robbed of its ornaments by an older bird.

Researchers believe the bowerbird also uses optical illusions to fool prospective mates, arranging smaller decorations near the structure and larger ones further away. The birds have even been observed correcting this pattern if it gets messed up. The lesson here, as it often is, is that males will go to great lengths to attract a mate.

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