Answer: My first guess would have been slugs (or snails), then birds, and finally mice or other small rodents although birds are another possibility. For snails, which leave less of a trail than slugs, you might try diatomaceous earth. For small critters, you might try a repellent spray such as a home-made garlic and/or pepper based concoction or one of the commercially prepared sprays. For birds, you might try the scare lines, an inflatable eye, or thick fishing line strung above the plants to confuse their depth perception. With some careful observation at different times of the day (and night) you might be able to discover the culprit!
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