Blue duck (Hymenolaimus malacorhynchos)
Other name: Whio
To see or hear a pair of blue ducks on a remote white-water river is one of the most memorable parts of any tramping trip in New Zealand's wild mountains. The sole member of the genus Hymenolaimus, and one of only three species that live year round on fast flowing rivers, blue ducks have many unique and interesting features. Today they are generally found on clean, fast-flowing streams and rivers in forested catchments of the lower North and South Islands, however before human arrival they where much more widespread, and some of the habitat they now occupy appears to be sub-optimal but perhaps provides some refuge from predators. They have a specialised bill with a fleshy black lip on the end of the upper mandible which, along with strong legs and large webbed feet, enable them to take aquatic insect larvae from the downstream surfaces of submerged rocks and logs. The slaty blue colour of the adult provides remarkable camouflage among river boulders. The ducklings hatch with relatively large feet and are capable of navigating turbulent rapids with apparent ease. The Maori name whio (the wh is pronounced f) is a good a description of the wheezy whistling call of the male.
Their uniquely adapted bill allows the blue duck to take aquatic insects from the surface or river boulders.
In 1773 Captain Cook referred to them as "Blue-grey Duck or the Whistling Duck, as some called them from the noise they made". Wilderness explorers are fortunate that the call of this iconic bird can still be heard today. The familiar New Zealand story of habitat destruction and the introduction of predatory mammals has led to its current endangered status. Recent estimates suggest there are about 640 pairs on North Island and 700 on South Island. Human activity on rivers often causes disturbance and introduced trout may compete for food. Stoats have been identified as one of the most important predators of blue ducks (particularly at the nest) and controlling these pests has lead to a more promising future for blue ducks, at least in some areas. Because pairs hold territories of a kilometre or more of river, large areas of often difficult country need to be managed in order to protect reasonable populations.
If you are in suitable habitat, finding blue ducks can be fairly easy—or it can be extremely tiring and frustrating! Often the first sign of them is the males whistle, or the guttural rattle of the female in response to a human intruder. Photographing them in the wild can present a few challenges. First there is the often remote terrain. If you are able to find birds closer to a road or major walking track things get a lot easier. However, this does take away part of the thrill of being in a quiet forested valley with just the birds, wind and water to break the silence. Then there is the largely crepuscular nature of blue ducks, meaning they are most active around dawn and dusk, and their river habitat which is often in the shade of forested hills. Consequently, photographers are usually struggling to get shutter speeds fast enough for sharp exposures. Fast lenses that can produce sharp images wide open at f/2.8–4.0 can help, and modern digital bodies with ever improving high ISO performance can be of huge benefit. Blue ducks can be fairly approachable, especially if you keep some swift water between you and them. Like all wildlife though, some individuals are a more shy than others, so best to leave those ones in peace and find more cooperative subjects.
Blue ducks are perfectly at home feeding in turbulent mountain streams. Strong legs and sharp claws help them cope with swift flowing water and slippery rocks.
My favourite lens for photographing these birds is a 300 mm f/2.8. When this doesn't have quite enough reach adding a 1.4× extender gives a 420 mm f/4 which is still optically superb. I also sometimes use a 2× extender when needed, but the resulting 600 mm f/5.6 is sharper when stopped down to at least f/8 which necessitates relatively bright conditions. It should go without saying that the use of a tripod is virtually mandatory in these conditions if you want to consistently produce sharp images. The pale pink bill is easily over exposed, especially when the camera's light meter is heavily influenced by dark rocks and water which may also be in the fame. Check the histogram and adjust exposure if needed.
Another important factor to bear in mind is the danger swift water can pose not only to camera gear but also to personal safety. Know how to cross rivers safely and always respect their power. Expect the rocks to be slippery and the water frigid year round.
Staff at Department of Conservation visitor centres should be able to provide information on where to find local blue ducks. A popular spot with birders is around Tongariro National Park, where pairs can regularly be seen relatively close to roads. Another good North Island location is the Whirinaki River in Whirinaki Forest Park, 90 km south-east of Rotorua. Intensive predator control in this area should benefit not only the ducks, but also forest birds such as kaka, kakariki and kereru which are often seen here high in the crowns of some of the finest tall podocarp forest left in the country. The Whirinaki Waterfalls Track provides some good opportunities to see ducks along about 5 km of the river.
To see more stock blue duck photos please visit my gallery.
References and further reading
The Field Guide to the Birds of New Zealand, by Barrie Heather and Hugh Robertson. Published 1996 by Viking.
Reader's Digest Complete Book of New Zealand Birds. Published 1985 by Reader's Digest.
New Zealand Birds (second edition), by W. R. B. Oliver. Published 1955 by Reed.