A number of white-faced herons at Snells Beach succumbed to an illness in early January, which may have been caused by botulism. Matakana Animal Sanctuary received four adult herons, and a call about a fifth, in the space of a week. Sanctuary owner Shawn Bishop received the first ill heron from Warkworth Department of Conservation on New Year’s day. Nicknamed Reefer, it was thin and weak, dragging its legs and using its wings like crutches to move. The herons were nursed back to health and released into the wild a fortnight later. Only one did not make it.
Shawn has previously only cared for young herons who fall from nesting trees.
“I’ve never seen a sick adult heron in 14 years, let alone five in a row,” she says. Forest and Bird seabird advocate Karen Baird says the symptoms seemed consistent with botulism, a form of food poisoning, but it could only be confirmed by an autopsy.Botulism is more common in hot weather, especially if there is stagnant water.
Karen says it can go through a small population quickly, but is not transferable from bird to bird. It can spread when a dead bird is eaten by maggots and the maggots are eaten by birds. One sick heron was found near Ariki Drive, in Snells Beach, by resident Jill Guillemin. She spotted it lying in the beachgrass between the path and water.
“He was floundering around and trying to pull himself forward on his wings but had hardly any strength.”
She bundled him up and took him to the Sanctuary where he was fed using a syringe and put on a course of antibiotics and anti-inflammatories.
White-faced Heron, Ardea (Egretta) novaehollandiae
Common native: The white-faced heron is New Zealand’s most common heron and one of our commonest large birds. It was self-introduced from Australia and began nesting in NZ in the 1940s, so is classified as a native.
Habitat and nesting: They are tree-top dwellers, favouring pine trees or macrocarpa growing near water. It is a tall, elegant, blue-grey bird that can be seen stalking its prey in almost any aquatic habitat, including damp pasture and playing fields.
Foraging and feeding: Foraging white-faced herons walk slowly with long, controlled steps, watching for any signs of prey, which is grabbed with lightning speed. They catch and consume a wide range of prey, including small fish, crabs, worms, insects, spiders, mice, lizards, tadpoles and frogs.
Voice: A harsh croak, usually given in flight.