SAN JOSE, Calif. -- A UC Santa Cruz biologist has determined that Jose and Clara, the two peregrine falcons living atop San Jose City Hall, have had two females and one male chick.

The chicks began to hatch in April. Three hatched and appeared to be healthy and growing strong. Clara mothered two females and a male chick last year as well, with a different partner.

SLIDESHOW: Researchers Put Tags On Falcon Chicks
SLIDESHOW: Falcon Eggs Hatch

The biologist, Brian Latta, also planned to retrieve a fourth egg, that did not hatch, so biologists can perform tests.

Scientists said the egg may have never been fertile.

The biologist said one of the chicks actually bit him on the thumb as he attempted to do his work.

Biologists from a research group also placed identification bands around the three chicks' feet. Similar bands were placed last year around the chicks Clara had with her former mate Jose.

Glenn Stewart of the Santa Cruz Predatory Bird Research Group said that this year's fourth egg might actually be the first one Clara laid and Carlos may not have fertilized it.

Both parents, Clara and Carlos, have been taking shifts protecting the chicks, hunting for food, and feeding the young.

Like babies of all species, the chicks spend most of their time eating and sleeping, watched by thousands of viewers of the FalconCam.

Scientists Raise Concerns Over Toxic Environment For Urban Falcons

Some scientists have speculated that toxic substances in the air could have affected the health of the falcons.

Researchers with the California Department of Toxic Substances in Berkeley discovered in a recent study the highest levels of some flame retardants ever found in wildlife among Bay Area peregrine falcons.

"We're finding levels of certain chemicals that haven't been found in other wildlife species," said research scientist Kim Hooper. "We think it's the location and the fact they live in the city with us."

Chemicals known as PBDEs are found in items like the plastic casings for televisions, mattresses and synthetic materials.

While there is no evidence they harm humans, Hooper said the chemicals have had an effect on lab animals.

"The levels are close enough to exposures we see in rats and mice that have neurological damage that we're concerned about the health of the peregrines as we're concerned about the welfare of infants and kids in the cities," Hooper said.

May 16 is also the new deadline for children in San Jose to submit their entry for what the falcon chicks should be named. The entry deadline was moved up so the winning names could be announced before the chicks begin to fly, officials said.

Carlos, Clara and their brood can be viewed on San Jose's Falcon Cam at SanJoseCa.gov.