What’s the natural world coming to? Researchers in Poland discover monster slugs eating baby birds right in their nests while scientists in Australia find catfish whose stomachs are filled with mice. Are these signs of the apocalypse? Should we stop them before they come after us?
The actual moment of slugs predating on nestlings isn’t easy to observe. You are more likely to come across the traces of the ‘tragedy’: dead or alive nestlings with heavy injuries, covered in slime – and often slugs’ droppings found nearby.
These monster slugs are slow, sneaky and sadistic, says Katarzyna Turzańska, a researcher at the University of Wroclaw. She was studying whitethroat birds when she found the evidence of a mucousy massacre. While local ornithologists said they’d never seen slugicide before, Turzańska found scattered reports around Europe of giant slugs attacking ground-nesting birds like whitethroats, wood and reed warblers and chiffchaff.
Why do these European giant slugs – the red slug (Arion rufus), the black slug (Arion ater), and the Spanish slug (Arion vulgaris) – act like such monsters? Turzańska explains in her study in the Journal of Avian Biology:
When a slug finds itself inside a nest – probably accidentally, or maybe by actively searching for this type of food – it just starts foraging on the living nestlings using its radula, or tongue covered in tiny teeth. The nestlings are unable to defend themselves and are eaten alive.
While it sounds horrible (and would make a great movie if the slugs added sleeping humans to their diet), Turzańska says the attacks are rare and the birds should worry more about other predators.
Like catfish? A study in the Journal of Arid Environments describes scientists in Australia finding multiple instances of lesser salmon catfish from the Ashburton River with stomachs filled with spinifex hopping mice (Notomys alexis), something these insect, crustacean and plant-eating fish are not known to dine on. While hopping mice burrow on the shore and could accidentally end up in the water, study lead author Erin Kelly of the Centre for Fish and Fisheries Research at Murdoch University, Perth, sees something more sinister happening.
Both species are nocturnal, and it is also possible that the catfish are actively hunting mice on the riverbank.
Kelly says this is the first report of high levels of terrestrial mammal consumption by any Australian catfish and it indicates the fish are changing their eating habits due to the cycles of flooding and drought brought on in part by climate change.
Understanding whether species like the lesser salmon catfish can adapt to their changing environment, and how the successful ones do it, will help us to conserve these creatures.
Conserve fish that are coming on shore and eating mammals? Is that a good idea? How about saving two birds with one stone and training them to eat monster snails?