Scaffolding went up last week at 927 Fifth Ave., surrounding Pale Male's nest.
Three babies were born this spring and one had a bad head injury this August, hawk watchers said.
Rat bait was found near the American Museum of Natural History, where a poisoned hawks was rescued.
A second sick baby hawk was taken out of Central Park to see if it has rat poisoning.
Pale Male's hawk baby fell sick from rat poison, a blood test found.
Necropsies revealed that three hawks were killed when they ingested rat poison.
The death of Riverside Park's female red-tailed hawk is one of several recent raptor deaths citywide.
Lincoln Karim was charged with illegal possession of a raptor.
Pale Male's girlfriend, Lola, was found dead on Sunday. The hawk has a new mate, a photographer says.
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