In the 1960s, the Mammalogy Department at the Bronx Zoo invented an exhibit specially for housing nocturnal animals. The Red Light Room in the Small Mammal House opened in 1961, and it used Red Lights to help create a day cycle for the animals. Red light is bright for humans and dim for the animals, so the room allowed visitors to see the animals being active in their nighttime environment. White light at night simulated day time, when the animals sleep. This method was then implemented in the World of Darkness exhibit at the zoo that opened in 1969, which is featured in this photo.

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