The Kenya Wildlife Service has begun moving 150 elephants from a small reserve to its largest national park because of overcrowding with rhinos, a spokesman said recently.

The first 40 elephants were tranquilized and moved by truck earlier this week from the Ngulia Rhino Sanctuary, about 185 miles east of Nairobi, under the program. The remainder were moved yesterday. “We need to protect the rhinos and allow them space so that their numbers can grow,” said Patrick Omondi, head of the wildlife service’s elephant program.

The wildlife service on September 25 also will begin relocating another 250 elephants to Tsavo National Park from the overcrowded Shimba Hills National Reserve, about 218 miles away, under a separate program.

Kenya has only 539 rhinos countrywide, about 70 in the Ngulia sanctuary. The country’s elephant population is estimated at 35,000, down from a peak of 167,000 in the 1970s.

Tsavo suffered its heaviest loss of elephants during the 1980s and early 1990s because of poaching that has since subsided with the help of a 1989 global ban on the ivory trade.