Three of the four heron species that breed in New Zealand – the white heron, white-faced heron and nankeen night heron – are at home in a variety of habitats, including estuaries, sandy or rocky shores, mudflats, wetlands, and river and lake margins. The reef heron is a coastal bird and is never seen inland. All four species have long legs and necks, and spear-like bills which they use to catch fish in shallow water. They are often solitary birds, but white-faced herons and white herons sometimes form small flocks, and nankeen night herons roost communally.
The dark-grey reef heron or matuku moana (Egretta sacra) is 66 centimetres long and weighs 400 grams. Their yellow-orange eyes and bill are striking, and during breeding they have long filamentous feathers on their head and back.
Reef herons can be found in Australia, Japan and eastern Asia, and they are distributed throughout the Pacific, where a white form of the species is common. Exclusively a coastal bird, its strongholds in New Zealand are Northland, the Coromandel Peninsula and the Marlborough Sounds.
These birds eat small fish and small eels, crabs and molluscs, which they sometimes catch with a clever ploy: they spread their wings around in front and snap up the fish, which are attracted to the temporary shadow.
Reef herons nest in crevices or beneath overhangs or vegetation. In September to December they lay two to four pale blue-green eggs, which both parents incubate. The young fledge at about six weeks, and live up to 14 years.
An Australian immigrant which began breeding in New Zealand only in the 1940s, the white-faced heron (Egretta novaehollandiae) has become the most populous heron in the country. Adaptable birds, they are equally at home along the coast or inland. They feed in aquatic environments and damp pastures, taking fish, tadpoles, frogs, insects, spiders, worms and even mice. They are about 66 centimetres long and weigh 550 grams.
Like other herons, male and female white-faced herons share in the raising of their young. They build the nest together, usually high in trees, and take turns to incubate the eggs and feed the nestlings. Breeding takes place any time between June and October, and from the three to five pale blue-green eggs, usually only two young survive. The chicks are wary of leaving the nest before they can fly – in contrast to nestlings of other herons, which like to clamber around the nesting tree until the parent returns with food. White-faced heron fledglings leave the nest at six weeks.
Nankeen night herons
Nankeen or rufous night herons (Nycticorax caledonicus) turned up on the Whanganui River between Pipiriki and Jerusalem in the early 1990s and started breeding. The population there was estimated at 50 birds in 2012. They are reddish-brown with a black cap, and have a short neck. Although their name suggests they are nocturnal, these herons sometimes feed during the day when breeding. Their main foods are fish, aquatic insects and frogs. Small and heavy compared to other New Zealand herons, nankeen night herons are 57 centimetres long and weigh 800 grams, and they fly with heavy wingbeats. They lay two to five pale blue-green eggs in September or October, and live up to 21 years. The young leave the nest within 50 days of hatching. They look very different from adults, being brown streaked with buff all over.
Seasonal visitors: cattle egret and little egret
Two species of herons – the cattle egret (Ardea ibis) and little egret (Egretta garzetta) – fly from Australia in May to spend winter on New Zealand farmland or coasts before returning to Australia in September to breed. A third of the size of white herons, these birds are sometimes mistaken for them.
Cattle egrets are much more common in New Zealand than little egrets, and are usually seen in flocks among cattle. Yellow-orange breeding plumage begins to show on their head and breast around September.