Now that it appears Rosie and Bobby may have at least one egg in their nest since Friday March 14th, I was inspired to calculate how long it may be before the first egg hatches then how long it may be until the first fledging.
Eggs typically hatch 28-35 days after being laid. The babies then usually fledge 42-46 days after hatching.
If all goes to plan, this spring’s first egg should hatch between April 4th and 10th (28-35 days after being laid). Following that, the first baby should fledge between May 16th and 20th (42-46 days after hatching).
Doing this calculation then inspired me to look into my blog archives and online reports to calculate how long it took for the previous years’ Washington Square Park babies to hatch then fledge.
I summarized the data in the table below. I discovered some interesting facts during my research.
For example, so far nearly all of the Washington Square Park babies have hatched at least two days past their expected ‘due date’. Also, the first birds to fledge left the nest at least two days after they were expected to. It seems slight disparities between the estimates and the actual dates may be attributed in part to the nest location’s latitude (as briefly mentioned in this linked Wikipedia article).
In 2011 Pip hatched 44 days after she was spotted (albeit in egg form) in Bobby and Violet’s nest (nine days after she was expected to hatch). She fledged 48 days after hatching.
In 2012 the first baby hatched 38 days after the first egg was laid. The two birds were laid four days apart yet hatched a day apart. They fledged on the same day (May 28th), 49 days after the first hatching.
In 2013 the first egg was laid on March the 7th. The first hatching took place 36 days afterward. The first baby fledged 49 days after the first egg hatched. The appearance of the second and third eggs in the nest were reported by others on March 19th but it’s not clear when they were actually laid (the Hawk cam was not yet on at the time so the laying was not seen by the public).
The 2014 column is still a mystery to be filled in as events unfold. Click on the table below to see it full size.
