European herring gull
An old-growth forest is located on Ormø, where a large great cormorant colony also breeds. Around 5% of the breeding great cormorants in Denmark breed on Ormø. Other birds that breed in Holsteinborg Nor include grey heron, common eider, European herring gull, common gull, black-headed gull, Arctic tern, mute swan, common coot and white-tailed eagle.