That's what beer is for - cheap plonk that is. Put in a disposable plastic or metal container about 2/3 of the way to the top. Bury said container level with the ground. Slugs crawl in and DIE DIE DIE. Dump container of dead slugs into hole, fill in, and repeat. Serves 'em right. That's how we used to do it anyway. No poisons used unless you count the beer. Slugs being nasty things, they like the smell, crawl in and drown.
What critters think slugs are tasty? I know you don't have grackles there; they're rather plain black birdies but they're murder on bugs.
I've seen grackles on Barbados. Noisy buggers. Our big corvids will go for slugs, if they can be bothered. Hedgehogs are the absolute best.
Hedgehogs aren't native here, but the grackles come through every so often. The love japanese beetles too. Crunch 'em like popcorn.