OK, I give; what kind of business are you in that has birds roosting in the rafters?
Is that all it says? Does it say “at the employer’s discretion” or “depending on the work area/job assignment”.
If you think the company has violated the contract, find your union steward and file a grievance.
If your workplace is so hot that the birds are dying and you’re not allowed to keep water at your station, call OSHA.
Probably a factory. We had lots of birds at the last place I worked. It’s hard to keep them out when loading doors are open. We also had frogs, cats, bats, and mice.