12K views · 1K reactions | Our Video of the Week features a pair of Cliff Swallows hard at work making a strong, secure nest with their very own version of bricks and mortar. Birds build their nests with a variety of materials depending on the species: from sticks and grasses, to spiderwebs, leaves, and even stones. Several swallow species, like Cliff Swallows, use the unique "brick-laying" construction method featured in this video. | Cornell Lab of Ornithology | Facebook