Peregrine falcons nesting on Pitt's Cathedral of Learning lay season's first egg

PITTSBURGH (KDKA) -- The peregrine falcons nesting on Pitt's Cathedral of Learning have laid their first egg of the season. 

Carla laid her first egg on Thursday at 4 p.m., the National Aviary said, sharing a video of the falcon on Facebook. There could be up to three more eggs, with Carla potentially laying one every 48 hours. 

The aviary says Carla knows when it's time to start incubating, and she won't start until the second-to-last egg is laid. Peregrine falcon males don't incubate the eggs, but viewers may spot Ecco temporarily help cover the eggs in inclement weather so Carla can rest. 

The National Aviary has been documenting the adventures of Carla and her mate Ecco since February. Carla is a newcomer to the nest this year after Morela ended the last season without any eggs and then disappeared around May. Carla laid claim to the nest box and Ecco shortly after that, the aviary said. 

This year, bird watchers can follow Carla and Ecco through the brand-new camera and microphone, which was installed by Pitt's IT department. 

Carla will incubate the eggs for the next 33 to 34 days before they start to hatch, so stay tuned.  

Pittsburghers are also waiting for a few other eggs to hatch. This year, the popular Hays bald eagles laid just one egg. There are also two eggs in the eagle nest at the U.S. Steel Irvin plant.