Today (April 30th) marks 33 days since the second to last egg was laid by this peregrine falcon pair. At this point full time incubation typically begins. Incubation for peregrine falcons is generally between 33-35 days so we have been watching closely today.
The female has been especially restless today, peering at the eggs and turning them often and vigorously. This evening we got the first glimpse of a pip in one of the eggs. A pip is the initial hole made in the egg. It is a chick’s first contact with the world outside the eggshell.
The hatching process began with the chick shifting inside the egg, bringing its head close to the air space inside the wide end of the egg. The chick pierced this airspace and took its first breath – no longer relying on oxygen brought across the egg’s membranes. With this first breath the chick was able to begin calling – soft “peeps” that the adults can hear and react to. During this stage the adults will often stare intently at the eggs listening as the chicks begin the hatching process. The chick began rasping against the shell with a sharp hard point on its bill – called the egg tooth, eventually creating the pip we can see in this video. Glimpses of the eggs through the day hinted at a pip – but this was the first clear indication. It is possible that a second egg has pipped as well, but the view was inconclusive. Peregrine falcon chicks typically hatch closely together, so we’d expect to see pips in multiple eggs. The hatching process can take anywhere from 24-48 hours. We’ll watch and hope to see chicks in the nest come morning.