I'm not a regular here, but I would put some bleach in a spray bottle and give them a squirt, then any stubborn areas, give a scrub with a brush. It shouldn't hurt your grass.

I use 1 part bleach to 10 parts water in a spray bottle. Then it is best if you can put in the sun to dry.

What are the statues made of ? (My HS English teacher just rolled in his grave.)

Maybe some lemon juice. That won't hurt any animals the way bleach would.