I only use slug pellets where the birds can't get at them, i.e. under a mesh cover. Further, I always leave them inside an array of weighted plastic cups (e.g. yoghurt pots) left on their sides so that the pellets don't touch the ground and they are less likely to get wet. The slugs seek them out, attracted by the smell, you don't need to scatter the pellets all over the soil. You can then dispose of the bodies where birds won't get them.
