I would look into unleaded pellets and reaproach the boss about using a pellet gun as part of the solution. There are som short distance pellets that disentegrate into what looks like paper. WCS one of the sponsors here I has a laser system that I think would solve your problem. All hazing works much better if you can kill some of them and the world will be a better place.
The only sure solution would be netting or closing it off with gypsom board. The solution may seem expensive but should they figure how much time =money they spend cleaning up bird (I'm stufid and don't no inny better) even without a workers comp claim they will realize the solution is cheap its the problem thats expensive.
I wish I worked there so I could get sick and start a wildlife business with my disability check.

That not fare I got yelled at for talking like that , there's know way I would work or let people work in starling crap, this birds migrates like wild ducks do that have the bird flue , bats migrate and now have the bat flue , coming soon starling flue to a bakery nere you , wonder if they have solved this starling problem yet , I know there back up here making me some green , got paid my service call last week to let one out of a down spout , i almost felt bad for taking her money all I had to do is move the black pipe 2" then fish the little rat out with a T bar !

Pesky, what he said about getting sick and getting disability because of starlings has some of the same aspects as what I said to you before.

But,

do you read what I just quoted you on?

do you see how you mention bird flu?

do you see how you mention bat flu?

Both of these mentions have nothing to do with human health in the United States.

Bird flu or properly termed highly pathogenic avian influenza (H5N1) was the subject of a massive surveillance program
to monitor wild ducks/geese and other avian species in the U.S. and around the world. It never caused any human illness
or death in the United States, therefore mentioning starlings migrating and saying people will get sick because of this is
not accurate and it misleads people who read it who may take your word for it.

The "bat flu" statements your making again don't come from this country and yet by you mentioning it online in this forum
you allow people to find your statements and think bats may be carrying a flu that may harm humans, which is not accurate again.

I don't take issue with anyone raising questions that is what a forum is for.

You however are making statements and statements can be treated as fact and quoted. So please understand the difference,
you won't catch me arguing with you about where to nail up a board on a house, or even how to trap wildlife, but when it comes
to wildlife disease issues the media already goes to far in sensationalizing these issues.

Do the bats and birds a favor and stick to what you can quote from good materials like extension publications, CDC website, OSHA
and other authorities.

Just sayin

The hole in the side of the building can be fixed by renting a lift. As for the place where the belt comes through the side of the building. A high volume air blower like those used to blow the water off your car at the car wash could be placed on the building. When the belt is turned off the blower comes on automaticaly. The birds will find it to difficul to enter and will soon find other places to go.

Paul, or you could start a disability business with your wildlife check.