Well, in my guess, i would most likely say, the slugs are less noticable, and therefore, predators, dont spot them, in which even if they have a main predator, it would be quite difficult to spot. In which on the other hand for the hedgehogs, they are bigger and easier to find. And they have more meat on them then the slugs, so Predators would eat them before the slugs... ~educated guess :)
The energy in hedgehogs is significantly less than in slugs due to energy loss at each trophic level, lower population sizes of predators, and their susceptibility to predation. Herbivores like slugs have access to more energy from plants, while predators like hedgehogs have less energy available to them. This results in a higher energy presence in slug populations compared to hedgehogs.
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