There's an island in Cornwall that's full of elastic bands.
Why? Because seabirds have been dropping them there - thinking they were food.
Mullion Island is a tiny island off the coast of Cornwall, and lots of black-backed and herring gulls roost there.
Rangers think the birds have been feeding on the mainland, then bringing what they thought were worms, back to the island.
Experts say they find loads of yellow, tan and green bands that had been regurgitated by the birds.
They also found green fishing nets and twine with the bands, and said it's likely the birds thought this was food too.
Rachel Holder is an area ranger for the National Trust. She said: "Ingested plastic and rubber is another factor in a long list of challenges which our gulls and other seabirds must contend with just to survive."
She added: "Places like Mullion Island should be sanctuaries for our seabirds, so it's distressing to see them become victims of human activity."