Modern architecture produces spectacular edifices with state-of-the-art materials, but there are equally, if not more impressive feats of engineering in the animal world, cleverly constructed with nature's resources. Whether they fly, swim or live on land, many creatures devote a lot of time and effort to creating their dwellings, and that process is the premise of the three-part PBS "Nature" series "Animal Homes."

Employing a variety of camera techniques including infrared and time-lapse photography, CGI, CT scans and animation to analyze structures inside and out, the series presents birds' nests, bears' dens, beavers' lodges and spiders' colonies as they've never been seen before.

"We went to such a broad array of different locations, spectacular places around the world, to find really interesting species, and some of them are examples of first times to be filmed," says host Chris Morgan, an ecologist and wildlife conservationist who has hosted and/or narrated 13 shows for "Nature." In the first episode, premiering April 8, the focus is on birds, their nests and some unusual avian behavior.

Case in point: the cowbird, which doesn't build a nest but moves into those built by other birds. "We have incredible footage of flocks of cowbirds patrolling mockingbirds' nesting sites, looking for them to leave," says filmmaker Ann Johnson Prum. "Sometimes they even break the eggs of the mockingbird and then leave. They cowbirds lay their eggs, and once they're laid, the mockingbirds can't necessarily tell which are which, so they're raising the baby cowbirds even though they're not theirs."

The story gets even stranger when a snake slithers into the nest and finds two chicks, a mockingbird and a cowbird, and eats the mockingbird. "It leaves the cowbird behind for the mockingbird mom to raise," says Morgan.

The detailed analysis of nests — from a tiny hummingbird's work to a huge osprey's home — is equally fascinating. "If you look at an osprey's nest, for instance, it just looks like a random pile of sticks, but it's actually held together by tension," notes Prum. A structural engineer performs a stress test on a variety of nests, including one made by Morgan, a complete failure. "I can't drive past a nest in the trees anymore without looking at them completely differently," he says.

Ovenbird nests are also engineering marvels. "It's about 5,000 beakfuls of mud to make that," says series executive producer Fred Kaufman. "There's a false wall, so anytime a predator comes by, it will look into that nest to see whether there are eggs to steal and there's nothing there; it's empty. But, in fact, there's an entrance to the roof of that structure where the eggs are hidden."

Location, location, location

The series' second episode explores the importance of location in building a home, and starts by showing the complex habitats of some very industrious beavers in Grand Teton National Park. "Some of these dams can be a half mile long. They raise the water level behind the dam so it floods an area, and the beavers can then access the trees that they eat. So by flooding it, making a pond, they can actually swim to these little through-channels that they also dig out to get further and further into the forests," says Morgan. "It's just mind-boggling what these little creatures are capable of, and it really does make you sort of think about them differently."

He was equally impressed by leafcutter ants, part of the third episode's segments on creatures that live in colonies. "These leafcutter ants in Costa Rica create underground colonies 10 million strong, weighing 40 tons," Morgan notes. "We would watch them harvesting the leaves from the treetops and bringing them back down to create fungus gardens where they would grow fungus to eat. The queen lays 30,000 eggs a day. It's all she does. She keeps this whole colony moving through this process of building and excavating."

The segment had its hazards for the host. "I was crawling into bear dens, but the only thing that drew blood was a leafcutter ant," he says. "Even on my calloused thumb, these leafcutter ants could cut right through it and it looked like someone had taken a razor blade to it. That's the only blood that I drew, even though we were rummaging around with bear cubs right in front of their mom."

'Animal Homes' host Chris Morgan holds a bird's egg

"Animal Homes" host Chris Morgan holds a bird's egg.

Prum used specialized cameras and lenses to get up close and personal with the subjects. "With the social spiders and with the leafcutter ants, we shot a lot of it with borescope lenses to give the viewer a sense of macro but also the bigger, larger world that these animals inhabit," she says. 

Getting the ospreys' nest-building process on film took the most time — "almost four and a half weeks, because the birds need rain and we had to wait for rain. Without mud, there's no building," she explains. In the end, they got about 40 hours of footage.

What was the toughest animal to represent? Shooting a puffin flock in Scotland — which involved getting inside the burrow to see the babies being fed and the moms on the eggs — was tricky. "We had to go up and over this huge cliff that was pretty scary. Not for the faint of heart," says Prum. "You know, a lot of it is just deep immersion in nature, so we're in remote places. If things did go wrong, we'd be in trouble. It's sort of like going off to war. You just prepare for every event, anything that could go wrong, and hope that it doesn't."

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