He learned a valuable lesson. The interns are college students doing internships to finish their degrees. I have some high school students doing community work. It is a daily job. Just taking care of the animals is a daily job.
Someone has to remove the feces and leftover food.
In the bird areas, the waste has to be scrubbed away. There is repainting of buildings, sweeping walkways, picking up trash . The further into the season the more trash there is. Antibacterial detergent is usually used, but Clorox is used in areas where animals have bacteria loads in their feces. If an animal is sick, cleaning methods may change.