Mourning Gecko, Lepidodactylus lugubris. They seem to have a population living wild in the reptile house. I've spotted them a few times in different habitats over the years.
I'd image this species doesn't intentionally inhabit Bronx, and therefore are essentially an introduced wild species rather than zoo animals - like the iguanas at ASDM.
this is actually a Hemidactylus species- head shape and foot structure don't match Lepidodactylus. My best guess would be flat-tailed house gecko (Hemidactylus platyurus)