A fourth peregrine falcon egg recently was laid in a specially constructed box at the Dubuque County Courthouse.
Both male and female falcons incubate the eggs and care for the young, according to Dubuque County Conservation.
A post from the group states that chicks should hatch during the beginning of May.
A pair of falcons began roosting in 2016 at the courthouse. That first year, their eggs rolled off the roof.
County conservation staff built the box and placed it on the high ledge.
In 2017, the pair raised one young; in 2018, two; and in 2019, three.
Their activities may be viewed on a live YouTube feed, found at .
The Iowa Department of Natural Resources estimates there are 15 to 30 nesting pairs of peregrine falcons across the state.
“Breeding pairs tend to be monogamous throughout their lifespan and return to the same nesting location year after year,” the DNR states.
The agency states that many peregrine falcons nest on tall buildings or smokestacks because “they resemble their natural nesting grounds: the faces of cliffs and bluffs.”
The birds are renowned for their speed. In a hunting dive, they can reach up to 240 mph.