Unfortunately worm farm predators are a real threat to the worm farmer, however, not all predators are that obvious. You built your worm farm so ignoring predators and letting the animals snack on or chemical harm your worms isn't going to fly.
Various birds love to eat worms, so do foxes, hedgehogs, leeches, toads, beetles, snakes, and a great many parasites, so that's the first worry when protecting your worms.
Another problem is in what you feed your worms, which may be the manure you probably get from livestock farms. The problem with that is is that those livestock take a lot of different medications and if you're not aware of what they are could affect your worms in a negative manner the medications may not always be completely digested and so the residue stacks up in the compost, which then goes to your worms.
To protect your worm bins you need to make sure they drain properly so that water is replaced. Stale water becomes contaminated over time, eventually causing harm to your worms so you also need to be careful about drainage material you use. There are those who opt to use shredded cardboard but some of the cardboard might have become contaminated by pesticides, which ultimately will affect your worms.
Yet another factor is what other predators consume the feeds you give to your worms since worms eat a lot and if the feed supply allotted to them is eaten by another predator then your worms won't be eating as they should be. Even supposing the predator isn't actually after the worms, the consequence is the same: your worm produce will rapidly decline. One specific problem here is the inevitable existence of raccoons on your farm because they tend to find their way into all kinds of containers, hidden or not and are able to open door latches.
Anyone who has birds on the farm with your worms there's no problem with the birds so long as you can keep them from finding interest in your worms. So you should find ways to keep the birds fed in areas away from your worms, to keep them from getting nosy and finally finding your worms and eating them.
The remaining type of predator neither consume worm feeds and it doesn't live on your farm. If your worm farm is found in or is even near a heavily populated area, this predator could be a human being, a thief or interlopers or nosy neighbors. So make sure your doors are not that easy to pick, and your fences are difficult to jump over so it's harder to steal worms from your farm.
