With the exception of a few local bats, New Zealand has no native land-based mammals. Its bird population adapted to this state of affairs – some, like the Kiwi, are flightless, or nest on the ground. When stoats, cats, possums and rats were introduced, they wreaked havoc: crunching down rare insects, killing fresh-hatched chicks, and slurping the eggs of ground-nesting birds.
Hedgehogs are also key culprits. “It’s increasingly coming to light how much damage they can do,” says Nick Foster, a PhD candidate at the University of Otago who is researching hedgehogs. A single, dedicated hedgehog will consume numerous native lizards, bird eggs, and wētā – a kind of large flightless cricket found only in New Zealand. One study found 283 wētā legs in a single hedgehog stomach. “That means in a 24-hour period this hedgehog has guzzled up 60 or so animals,” Foster says. “It’s a banquet.”