White-faced heron and Reef heron (Matuku moana)
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The white-faced heron (sometimes mistakenly called a blue heron) and the reef heron are both known as Matuku moana.
The white-faced heron is the species most commonly seen in New Zealand and is present in large numbers throughout. As its name indicates it can be recognised by its distinctive white face, neck and throat. The overall plumage colour is two-toned bluish grey, with black bill and yellow-green legs. It is a recently self-introduced native species first recorded breeding in New Zealand in the early 1940’s.
Since that time its population has rapidly expanded and it is now considered one of New Zealand's commonest large birds. Its Conservation status is protected native. They occupy a vast array of habitats from inland freshwater lakes, farm dams, swamps, rivers and streams to open farm grassland, town parks, coastal estuaries, harbours, mudflats, rocky shorelines and sandy beaches.
White-faced heron are solitary breeders, choosing nest sites high up in tall trees, usually pines, macrocarpas and gums. Their nests are large untidy structures built from small branches, and sticks, either in the fork of a tree or well out on a branch. Clutches vary from 3-5 pale green eggs which hatch following about 26 days of incubation. The chicks are fed by both parents until they are able to fly at around 6 weeks old. It is unusual for the parents to successfully raise more than 2 of the chicks to this age.
Occasionally exceptional feeding opportunities arise, such as flooded pastures providing an abundance of earthworms and other invertebrates, or drying river beds, streams and other wetlands exposing concentrated numbers of distressed fish, eels and frogs, etc. Herons along with other bird species will congregate to take advantage of this bounty. It is however far more common for white-faced herons to be solitary feeders targeting a wide range of prey including crabs, worms, insects, lizards and even mice.
The reef heron is roughly the same size as the white-faced heron but has much darker slaty grey plumage, yellowish bill and relatively short yellow-green legs. It is primarily an inhabitant of the rocky coast where it stalks small fish in rock pools and other shallow open beach and estuarine waters. They are seldom seen inland. One or two birds are occasionally seen in our Whangamatā Harbour but often mistakenly identified as a white-faced herons.
This species is rare, the NZ population estimated to number between 300 and 500 birds and declining. Its Conservation Status is Nationally Endangered. The main cause for their decline here is thought to be predation by introduced rats, mustelids and feral cats. The species is widely distributed throughout eastern Asia, the Pacific Islands and Australia.
Reef herons are best described as a shy, wary, solitary species. They nest singly and avoid congregating with groups of other birds, even those of their own species. The territories of adjacent pairs are usually many kilometres apart, and their nests situated in dark hidden places such as rocky cliff crevices, caverns and beneath the exposed, tangled roots of coastal vegetation such as pohutukawa trees. Nests are a platform of sticks, twigs and seaweed. Usually 2-3 eggs are laid and incubated by both parents, hatching after about 27 days. They are fed by their parents with regurgitated food for around 6 weeks before beginning to fly and fend for themselves.
Reef heron's dark grey plumage is excellent camouflage when it is travelling along its preferred habitat of rocky shorelines fossicking for food. Their diet is mainly small fish, eels, flounder, crabs, shellfish and some marine invertebrates. They hunt slowly and stealthily, often crouching with their head and body horizontal and their neck curved. Sometimes they will spread their wings and freeze in that crouched position, creating a shaded area beneath them to attract prey within reach.
— John Adams. Whangamatā Harbour Care
