PHOTO: James Reardon ©

Introduction

The at risk fernbird/mātātā is an endemic species which inhabits wetlands throughout New Zealand.

The fernbird (Bowdleria punctata), or mātātā as it is known to Maori, is a small insectivorous passerine. Fernbirds are closely related to the grassbirds Megalurus of Australia and Africa, and are sometimes included in that genus.

The current geographical variation consists of five subspecies. North Island fernbird B. p. vealeae (At Risk/Declining); South Island fernbird B. p. punctata (At Risk/Declining); Stewart Island fernbird B. p. stewartiana (Threatened/Nationally Vulnerable); Codfish Island fernbird B. p. wilsoni (At Risk/Naturally Uncommon); Snares Island fernbird B. p. caudata (At Risk/Naturally Uncommon). The only other member of this endemic genus was the extinct Chatham Island fernbird B. rufescens.

Snares fernbird/mātātā on branch.
Snares fernbird/mātātā on branch.

North Island fernbird nest containing two eggs and one chick.
North Island fernbird nest

Fernbirds inhabit wetlands throughout New Zealand, but are rarely seen because of their secretive behaviour and excellent camouflage. More often heard than seen, fernbirds are skulking sparrow-sized birds that on the three main islands are found mainly in dense, low wetland vegetation.

They have disappeared from large areas of New Zealand, including Wairarapa, Wellington and Canterbury, but remain common on the West Coast and in pockets of suitable habitat from Northland to Stewart Island. Fernbirds occupy dry shrubland and tussock habitat at a few sites, including in the Far North and on some islands.

Fernbirds have declined significantly since humans began draining wetlands and are now classed globally as at risk, declining.

Where are they found?

  • Fernbird are widely if patchily distributed and locally common in dense wetland vegetation throughout New Zealand.
  • Absent from the southern North Island and Canterbury.
  • Locally common in dry shrubland near North Cape, tussock-covered frost flats up to 1000 m altitude in Tongariro and Kahurangi National Parks, pakihi vegetation on the West Coast, reedbeds growing in saltmarshes in the West Coast, Otago and Southland, and tussock above 300 m in southern Otago and Southland.
  • Occurs in dense kiekie on the Open Bay Islands (off Haast), and in tussock grassland and under low tree-daisy (Olearia) forest and kokomuka (Hebe elliptica) shrubland on muttonbird islands and the Snares Islands.
  • Common on Great Barrier Island.
  • Formerly present on Great King Island (Three Kings Islands) and Aldermen Islands.
  • Introduced to Tiritiri Matangi Island.
  • Otherwise absent from islands off North Island, in Marlborough Sounds and in Fiordland.

Population estimates: ~1500 pairs estimated on Snares Islands (8 pairs/ha); 2.4 pairs/ha near Whangarei; 3 birds/ha at Tiropahi, West Coast; 1.89 birds per 5-min count on Great Barrier Island.

Fernbird/mātātā facts

Fernbirds are small (18 cm, 35 g), long-tailed songbirds that are predominantly streaked brown above and pale below. The mainland subspecies have a chestnut cap and a prominent pale superciliary stripe. The loosely-barbed plain brown tail feathers have a distinctive tattered appearance.

Fernbirds are poor fliers; they typically scramble through dense vegetation, though occasionally fly short distances with their tail hanging down, just above the vegetation. No banded birds have moved more than 5 km, but fernbirds occasionally turn up at sites tens of kilometres from known populations.

Fernbirds have a gamey smell which makes them irresistible to dogs trained for game hunting or as conservation dogs.

The oldest known bird was 6.5 years.

Fernbird are heard more often than seen. Calls are often the only evidence that they are present in a wetland. Their distinctive call is a characteristic ‘u-tick’ given as a duet by members of a pair. Pairs keep in contact with these duet calls.

Although difficult to observe due to the dense habitat they occupy, fernbirds may approach observers closely, especially in response to mimicked calls.

Breeding

South Island fernbird/mātātā male at nest.
South Island fernbird/mātātā male at nest

South Island fernbird/mātātā on manuka.
South Island fernbird/mātātā on manuka

Fernbird are monogamous, breeding from spring to summer.

They are multi-brooded, raising up to three successful broods per season.

A deep, woven, feather-lined cup of fine grass or sedge leaves is concealed in dense vegetation, usually less than 1 metre above ground or water.

Clutch size typically 2 on islands and 3-4 on mainland. Eggs are laid on consecutive days.

Egg colouration varies per subspecies. South Island fernbird eggs are white spotted with reddish brown. North Island fernbird eggs are dull white or pinkish, closely dotted with violet and purple-brown predominantly at larger end.

Both members of the pair incubate the eggs and care for the young. Nestling period is 15-18 days.

Age at first breeding, age at first independence and longevity are unknown.

Diet

Fernbird diet consists of insects (especially caterpillars, flies, beetles and moths), spiders and other small invertebrates. Occasionally seeds and fruit; one record of a skink. On southern islands, fernbirds forage frequently among leaf litter, holding up leaves with one foot while inspecting the underside, and they occasionally enter seabird burrows. They also catch blowflies on sleeping sea lions (Snares Islands). 

Fernbirds are a potential indicator of wetland health because they are dependent on the presence of high quality and ecologically diverse habitats and rich food supplies. 

Similar species: the only other skulking passerine found in dense vegetation is the introduced dunnock, which is smaller, has darker underparts, a shorter tail and a very different call.

Threats

Many local populations have been lost due to drainage of wetlands and conversion to pasture, combined with predation by introduced mammals. Several populations on muttonbird islands were wiped out by introduced ship rats (Solomon, Pukeweka and Big South Cape Islands) and weka (Kundy and Jacky Lee Islands). Fernbirds died out on Great King and Aldermen Islands, probably due to vegetation succession. A few island populations have been established or reestablished by translocation, e.g. North Island fernbirds to Tiritiri Matangi Island, Stewart Island fernbirds to Kundy Island, and Codfish Island fernbirds to Putauhinu Island.

The main threats to fernbird/mātātā are:

  • Habitat clearance and drainage.
  • Continued habitat modification including the loss of food supplies.
  • Predation by introduced mammals such as cats, rats, dogs and mustelids.

Other factors which impact on the fernbird/mātātā:

  • Road-kills and flying into power lines are also causes of deaths.
  • Nesting crakes are sensitive to disturbance by humans.

Our work

Stewart Island fernbird/mātātā, Big Island.
Stewart Island fernbird/mātātā, Big Island

Snares fernbird/mātātā, Snares Island.
Snares fernbird/mātātā, Snares Island

Wetlands support a wide range of threatened bird species in New Zealand. However, management techniques for restoring their populations are poorly developed.
 
DOC is focusing on developing methods for surveying fernbirds systematically. These methods will enable people to establish baseline data and distribution maps; identify important wetland habitat types for conservation and measure the response to management such as pest control; and habitat maintenance and restoration.

We have been developing ‘call counts’ for fernbirds. These take place with either an observer listening for set times at dawn or dusk using call lures, or with new automatic recorders (electronic recorders developed by the DOC Electronics Lab) recording calls remotely.

We are also actively developing methods for restoring wetlands through the Arawai Kākāriki Programme.

You can help

Report sightings or calls of fernbird to your nearest DOC office.

Help protect New Zealand's native birds

  • Volunteer with DOC or other groups to control predators and restore bird habitats.
  • Don’t throw rubbish into water ways or storm drains.
  • Set traps for stoats or rats on your property. Get more information from your local DOC office.
  • Put a bell on your cat's collar, feed it well, and keep it indoors at night.
  • Plant a range of native plants that provide food year-round to encourage birds into your garden.
When visiting parks and beaches
  • Only take dogs to areas that allow them, and keep your dog under control.
  • Prevent the spread of pests. Check your gear for mice and rats when visiting pest-free islands.
  • Use available access ways to get to the beach. Stay out of fenced-off areas. Leave nesting shore birds alone.
  • Get your dog trained in avian awareness, and help save forest birds like kiwi and weka.
  • Follow the water care code. Keep water craft speed to 5 knots within 200 metres of the shore.
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