All four of the baby peregrine falcons that hatched in the nest atop the PG&E building on Beale Street in downtown SF have survived their first month and will soon begin to fledge — gaining the adult feathers they need for flight.

What were once just shrieking white puffballs have already become shrieking gray and white almost-fledglings, and the four chicks born in early April are still awaiting names. PG&E was seeking public input for naming the birds last week on Twitter, and we should hear the picks soon. Two of the chicks are males, and two are females.

Last week, on May 3, researchers with the University of California, Santa Cruz Predatory Bird Research Group came to check on the birds, check their weights, and put bands around their legs so that they can later be identified. You can see a video of the banding process below, and suffice it to say neither babies nor parents were very happy about what was going on.

Also, as you can see, with the young birds shedding their white baby plumage — and relieving themselves all over — the nesting area and ledge are now a mess.

And in just the week since the chicks were banded, several of them have already lost a lot of that white fluffy plumage, and are getting close to full fledging. In the next three weeks, the birds will begin learning to fly, which doesn't always go successfully. But we can hope!

Below, from Monday morning, you can see video of the birds' dad, Canyon, delivering some prey for them to share, but one of the young birds snatches and runs off, keeping it all to himself. His little sister, who still has more white plumage, waits until the 7:35 mark in the video to move in and snatch the remains of the food from him.

Zeka Glucs, the director of UC Santa Cruz's predatory bird group, said in a statement to PG&E last week that as more people begin returning to downtown San Francisco, they may have sightings of the four fledglings in the coming months, and if they can see their band number they'll be able to report back on the sighting — perhaps to this Google group.

Glucs adds that this nest atop PG&E's headquarters has been hugely important both the rebounding of the peregrine population, and to research in general.

"In addition to 77 Beale’s importance as an indicator of species recovery, this nest has provided deep connection with the peregrine-recovery story for people around the world," Glucs said. "This nest and its webcam are the No. 1 personal peregrine encounter I hear about when I tell people what I do for a living or give a presentation at a school or educational event."

She added that it's not entirely clear why Val, the chicks' mom, has returned to this nest so often, but it's clearly well situated.

"Why they choose the nesting places they choose is such a big question," Glucs said. "There are lots of other buildings around, but there’s something about the orientation of this building to the sun, the wind and the bay that’s perfect for them."

Hatchlings from this nest have gone on to reproduce from other nests around the Bay Area in the last two decades. The nest has been here since 2004, with a live camera feed on it since 2007 – and in that time, 45 hatchlings have made it to maturity from the nest.

One of the birds from the 2011 brood, Phoenix, started a nest of his own in Richmond that he continues returning to. And another from 2016, Grace, took over a nest in San Jose last year and produced two clutches of eggs there, including one with two birds that survived their first fledge last year.

Over in Berkeley, atop the Campanile tower on the Cal campus, falcon couple Annie and Grinnell produced three chicks this spring who are few weeks behind the SF brood in their growth.

Previously: Video: Watch the Four Peregrine Falcon Hatchlings Get Fed In Downtown SF Nest