July 2, 2016 at 8:24 pm
In the face of environmental change, the tawaki is at last receiving the scientific attention needed to protect one of the world’s rarest penguin species.
Many New Zealanders know the little blue penguins that live and breed along most of our mainland coastlines, and we hold the yellow-eyed penguin that adorns our $5 bill in our hands every day. But faced with a photo of a Fiordland crested penguin/tawaki, most of us likely wouldn’t recognise it as another native species. Tawaki belong to the group of crested penguins that boast striking yellow feathers above their eyes. Unfortunately, most crested penguin populations have been declining during the last century, and tawaki do not seem to be an exception. The population is estimated to range between 5,000 and 6,000 birds, and at some sites their numbers are believed to have declined by as much as 30 percent over just 10 years.
But there is considerable uncertainty about the numbers. Unlike other crested penguins, who breed in densely packed colonies, tawaki breed in scattered colonies, mostly in forests along the rugged coastlines of South Westland, Fiordland, Stewart Island/Rakiura and outlying islands. They are true forest penguins that epitomise the wrongness of the penguins-on-ice stereotype. It also means that it is no mean feat finding – and counting – these penguins in the remote and wild areas they inhabit.
Their nesting habitat ranges from sea level to 100m elevation, and they like to breed in impenetrable vegetation. Some pairs have even been found breeding in sea caves with access only through submerged entrances. This means it is next to impossible to get accurate estimates of tawaki populations throughout their entire range.
In 2014, Robin Long surveyed a 60km stretch of coastline between Haast and Milford Sound to identify and accurately census tawaki breeding colonies in the area. She found at least 870 pairs – a stark contrast to the 150 pairs reported in a 1994 survey. However, this likely represents an underestimate in the earlier census rather than an increase in actual penguin numbers. By repeating her 2014 survey during the next 10 years, Robin will record changes in penguin numbers, which will be used to extrapolate trends of the entire tawaki population.
Determining tawaki population size and trends is one thing. Coming up with conservation measures to ensure the survival of the species is another. It is equally important to determine which key threats affect the penguins and what options we have to mitigate these threats.
Tawaki breed on land but find their food at sea. On land, introduced predators – stoats, possums and dogs – may prey on the penguins and their offspring, while human activities can disturb breeding birds and cause them to abandon sites. At sea, rising ocean temperatures probably disrupt prey availability, fisheries may compete for resources or result in accidental bycatch, and pollution in the wake of proposed oil exploration could also become a major problem for the tawaki.
To date, very little is known about tawaki ecology. For decades, the inaccessibility of their breeding sites was a major barrier for scientific investigation. However, by using new technologies to observe and track the penguins, two research groups from the West Coast Penguin Trust and Otago University have joined forces to fill in significant gaps in our knowledge about the species.
Using motion-sensing cameras at nest sites, the trust is carrying out a study to determine the impact of introduced predators on tawaki. In the past two years, thousands of videos have been recorded. Although most video clips show penguins preening or gathering nest material, occasionally intruders – stoats, possums and rats – enter the scene. While it appears that possums and rats keep a respectful distance from the breeding birds, stoat attacks on chicks caused some monitored nests to fail.
The Tawaki Project is studying the penguins’ marine biology. Using miniaturised GPS dive loggers, Otago University researchers Thomas Mattern and Ursula Ellenberg study tawaki’s foraging ranges and diving behaviour. First results indicate that climate substantially influences the birds’ foraging success, but apparently this depends largely on the region in which the penguins breed. During the strong 2015 El Niño, tawaki from Jackson Head, Haast, had to travel hundreds of kilometres to find food for their chicks while others in Milford Sound could obtain ample food without leaving the fiord.
Both projects will significantly expand our knowledge of tawaki and provide much needed information for fact-based management of New Zealand’s unique and enigmatic forest penguin. To find out more, see www.tawaki-project.org and www.bluepenguin.org.nz.