Scientists in New Zealand have been attaching special backpacks onto hedgehogs to try to work out where they go and what they do!
Hedgehogs were introduced into New Zealand in the 1800s. They may look cute, but some people think they've been damaging the environment.
Nothing hunts these hedgehogs so their numbers have been increasing rapidly.
Now there are worries that they are threatening New Zealand's lizards, insects and ground-nesting birds.
The backpacks use satellites to track the movement of the hedgehogs. They are light and designed not to slow down the animal or stop it rolling into a ball or nesting.
Scientists have been studying 28 hedgehogs. The backpacks send back information about the animals every five minutes for five days.
Over five days, they found that hedgehogs can travel up to a mile in one direction, but usually stay in one spot for food.
The study was done in the Godley Valley area of New Zealand's south island. It's hoped the information will help conservation in the country.