Two troops of gorillas who have been hanging out at the Denver Zoo while their new exhibit is being built in California are preparing to end their Colorado summer.

The zoo will send them off with a wild bon boyage party at 10 a.m. Wednesday. They'll get to scarf down yummy treats, including Jello and Popsicles. Going-away cards from other Denver Zoo residents will be on display at the public event.

The troop came to Denver in April 2003. Their new exhibit, Campo Gorilla Reserve at the Los Angeles Zoo, is now ready for them and will open to the public in November. It includes innovative behavioral enrichment tools and extensive of indigenous trees, plants and othe native species.

In Denver, the troops rotate use of a one-acre outdoor yard and a large indoor dayroom. Among those headed for LA are a 20-year-old male, Kelly; a 31-year-old female, Evelyn; a 23-year-old female, Rapunzel, and her 2-year-old daughter, Tinga, who was born at Denver Zoo.

Ronda Schwetz, area supervisor of primates at the Denver Zoo, said, "The move is bittersweet. We have enjoyed caring for these gorillas for last four years."

The gorillas at Denver Zoo know several behaviors that zookeepers work on with them regularly to stimulate their minds and help them to cooperate in their own care. The gorillas know behaviors such as "shoulder" where the animal will press their shoulder against the mesh to allow veterinarians to give an injection or "tongue" where they stick out their tongue to allow staff to examine for any cuts or injuries. Positive reinforcement in the form of praise and a favorite snack is provided when the behaviors are given by the animals.

In addition to these routine behaviors, one of the gorillas heading back to Los Angeles Zoo, Evelyn, has been spending a lot of time painting! Zookeepers say Evelyn seems to really enjoy painting and has already created several works of art. Painting is a mentally stimulating activity for Evelyn that has proved to be enjoyable for both her and the zookeepers working with her.

After the four gorillas return to Los Angeles in mid-September, visitors will still be able to see the Denver Zoo's five remaining gorillas, 20-year-old male, Jim; 30-year old female, Bassa; 20-year-old female Angel; 29-year-old female, Jo Ray K; and her 3-year-old son, Jabali, who was born in Denver on May 29, 2004.

For information, call 303-376-4800 and www.denverzoo.org.