CHICAGO, - Officials at Chicago's Lincoln Park Zoo said a rare Bolivian gray titi monkey was born at the facility. The officials said Tuesday the monkey, one of only about 50 of its species in U.S. zoos, was born to mother Delasol, 21, the oldest titi monkey to give birth in a North American zoo, and father Ocala, 15, the Chicago Sun-Times reported Tuesday. The zoo said the monkey is the ninth child born to the couple. Officials said the birth is a "big deal" due to the declining population of the species in the wild.