Update: As of 3:30 pm PDT, the fourth egg has not arrived. According to bird cam project leader Charles Eldermire, when the female's getting ready to lay her egg, she "puffs up her body and her plumes puff out, then relaxes. This can go on for a little while, then she kind of puffs up and cranes her neck, and pushes the egg out."

We brought you the California Condor Cam, the world-famous Decorah Eagle Cam, and now it's time for the Great Blue Heron Cam. The heron in this nest has been laying her eggs almost like clockwork every 48 hours, which means the fourth egg should drop today around 3 p.m. PDT (but we recommend tuning in no later than 2 p.m.).

Great Blue Herons lay between two and six 2-inch-long eggs per clutch, and they can have up to two broods in a single year. The stars of the Heron cam, run by the Cornell Lab of Ornithology, have laid four eggs every year for the past three years, and all of them have fledged.

The chicks will hatch after an incubation period of about four weeks, and they'll have bluish eyes and pale gray down feathers. They'll stay in the nest with their parents between 7 and 12 weeks.

The Great Blue Heron is the largest of the North American herons. These long-legged birds live in Mexico during the winter and in Cuba, Baja California and most of the continental United States throughout the year. They typically live along coasts, marshes, sloughs, riverbanks, ponds and lakes. The blue-gray birds prey on fish, amphibians, reptiles, small mammals, insects and other birds.

During the breeding season in the summer, they form colonies called heronries to construct nests, which are mostly found high off the ground in trees. Once males arrive at nest sites, they wait for females to pass by and then court them. When it's time to make the nest, the male will gather most of building materials for the female, while she builds its saucer-shaped base with pine needles, moss, reeds, dry grass, leaves and small twigs. Building a nest could take up to two weeks. Sometimes herons reuse the same nest from one year to the next.

The Cornell Lab, which set up the heron cam, began streaming still pictures from nest cameras in 1998, and in 2012 they started the BirdCam project, which streams videos of birds throughout the country throughout the year.

"The amazing thing is that the public was at the crest of that wave of discovery right there next to us," wrote bird cam project leader Charles Eldermire in an e-mail. "The relevancy of those observations, both to science and in the individual's own experience, is a very empowering and engaging tool to connect people with birds and the natural world.Video and Image: Cornell Lab of Ornithology/Livestream.