The National Aviary has zoomed the Gulf Tower falconcam because this weekend -- or early next week -- the peregrine eggs at the Gulf Tower will start to hatch. It's time for Hatch Watch!
Peregrine falcons delay the start of incubation until the female has laid her next-to-last egg, then incubation lasts about 32 days plus or minus a day or two. In this way, nearly all the eggs hatch within 24 hours. (The last egg hatches a day or two later.) The trick for us humans is figuring out when incubation actually begins.
This year we thought Dori finished laying eggs on March 15, when she had four, but she surprised us with a fifth egg before dawn on March 17. Her next-to-last egg was on March 15 so my guess is that incubation began around March 16. That means Day 32 is on April 17.
Here's another way to calculate it. When Dori laid five eggs in 2014, the number of days from first egg to hatch was 41 days. This year her first egg was on March 8. 41 days later is April 18.
But I don't really know.
If you're a member of the Pittsburgh Falconuts Facebook page you've seen that John English predicted Hatch Date as April 15 or 16 plus or minus two days. My guess is April 17 or 18. Maybe you have a guess, too. Only Dori and Louie know for sure.
Watch the National Aviary falconcam at the Gulf Tower for pips in the eggs. Here's more information on what to look for:
(snapshot from the National Aviary falconcam in 2014 at the Gulf Tower)