NEW YORK (Reuters) - A man released as many as 50 guinea pigs in Central Park for still unknown reasons and 10 of them may have perished in the snow or been killed by birds that prey on small animals, officials said Tuesday. Park rangers rescued 33 of the guinea pigs after park attendants saw a man releasing between 40 and 50 from a cage Thursday night, raising fears they could be carrying diseases that might be passed on to people or other animals. "We have been searching for three days but most likely because of the snow, unfortunately the rest may have frozen to death," New York City Department of Parks and Recreation spokesman Corey Salsberg said. Freezing rain and snow fell over the weekend in New York, with five inches (13 cm) of snow recorded in the park Sunday. The search for the guinea pigs would continue however, the spokesman said. He said the guinea pigs, small furry animals indigenous to South America, could have been killed by hawks, ospreys, owls and other birds of prey who eat rodents. "In Central Park in New York City they are not suited to survive in the environment," Salsberg said. "They are imported here all the time as pets or for laboratory experiments so they are domesticated. They haven't lived in the wild for about 100 years, even in South America." No one has been arrested for releasing the guinea pigs, considered a crime under laws governing the control of animals in the public park. A $1,000 reward has been posted for the capture and conviction of the man. Park officials believe it may have been the work of a pet shop owner trying to get rid of the animals or an animal-rights activist who took them from a laboratory. Salsberg said the rescued guinea pigs had been checked for diseases and appeared to be in good health. The City Center for Animal Care and Control was looking for homes for them.