Temperatures in Richmond took a dip in early April, with night-time temperatures getting into the 40’s and 30’s. This means that the adults must keep the eggs warm by incubating. Many bird species, including peregrine falcons, have a special adaptation that helps them keep their eggs warm. The birds develop featherless areas on their breast called brood patches. These areas develop thickened skin and an increased blood flow that helps the birds pass body heat along to the developing embryos inside the eggs. In this video clip from March 10th we can see the female falcon plucking feathers from the area of her brood patch in preparation for egg-laying. Male peregrine falcons also develop brood patches and help with incubation, but as the female will do the majority of this work her brood patch is much more developed.
We will continue to keep a close eye on the nest over the coming week as the eggs should be due to hatch. Peregrine falcon eggs are typically incubated for 33-35 days beginning with the second to last (penultimate) egg of a clutch. We aren’t sure when the penultimate egg was laid but believe it to be on or around March 15th.