Dyrehaven is packed with old hollow trees, and therefore there are many hole-brooding birds; primarily tawny owls, black woodpeckers and the more common spotted woodpecker. The tree creeper also thrives in old trees, and at Mølleåen you can see ravens, nightingales, kingfishers and dippers.
Bats, and not least the noctule bat, hibernate in the hollow trees.
In the middle of the Eremitagesletten is the Iglehullet waterhole and this, as well as other waterholes, have medicinal leeches. This species has been used in medicine for thousands of years, primarily for blood-letting. The medicinal leech can be up to 15 cm long. Other old species in the waterholes include fairy shrimp and horseshoe crabs.