The Fernbird
Bowdleria punctata
Written by Rebecca Heenan (Lincoln University)
July 2005
Edited by Michael Hudson, Lincoln University, September 2006
Taxonomy
- Scientific name: Bowdleria punctata (Quoy and Gaimard) subspecies punctata
- Popular Common names: Fernbird, matata
- Other common names: Swamp thrush, grass bird
- Kingdom: Animalia
- Phylum: Chordata
- Class: Aves (the birds)
- Order: Passeriformes (the song birds)
- Family: Syviidae (old world warblers)
- New Zealand Status: native (endemic)
- Taxonomy sources: Best (1985), Heather and Robertson (1996).
Identification
Species Description
The fernbird is a small bird of approximately 18 cm in length (Orbell, 2003). A distinctive spiky, fern-like tail allows for easy identification (Chambers, 1989). The tail consists of ten to twelve long feathers that are dark brown in colour with golden brown edges. The upper surface of the fernbird body has the same golden brown colouring as that of the tail feathers, but incorporates the golden brown with dark brown longitudinal streaks. The ventral surface of the fernbird body is white with brownish-black spots. These spots increase in size from the chin to the abdomen (but are absent from the surface of the abdomen). The South Island fernbird has larger spots than the North Island fernbird (Best, 1985).
The fernbird has approximately five different calls; the ‘Uu-tick’ call is the most common of these. Consisting of two parts the ‘Uu-tick’ call starts with a low frequency tone followed by a sharp metallic sound. The call may be given completely by the male or sometimes as a duet between a male and a female. The duet is possibly to uphold the pair’s territory and to maintain contact between them (Orbell, 2003).
Similar species
The fernbird species Bowdleria punctata consists of six subspecies:
- Bowdleria punctata subsp. vealeae (North Island Fernbird)
- Bowdleria punctata subsp. punctata (South Island Fernbird)
- Bowdleria punctata subsp. wilsoni (Codfish Island Fernbird)
- Bowdleria punctata subsp. stewartiana (Stewart Island Fernbird)
- Bowdleria punctata subsp. caudate (Snares Fernbird)
- Bowdleria punctata subsp. rufescens (Chatham Island Fernbird)
Geographic Distribution
Full natural and naturalised range
As an endemic species, the fernbird only occurs in New Zealand (Heather and Robertson, 1996).
New Zealand range
Widely spread throughout New Zealand the fernbird inhabit the North, South, Great Barrier, Aldermen, Stewart, Codfish, Chatman and Snares Islands (Heather and Robertson, 1996).
Canterbury range
The fernbird was once widely spread throughout Canterbury’s wetlands. Drainage and cultivation of the majority of its natural habitat has resulted in the fernbird becoming locally extinct from Canterbury since 1898 (Oliver, 1955).
Natural History in Canterbury
Habitats
The main habitat of the fernbird is close to the ground in the thick vegetation of: drier wetlands; tussock covered forest flats and salt marsh; low manuka (Leptospermum scoparium) shrubs; and even in some young pine (Pinus) plantations (Heather and Robertson, 1996). As well as these wetter habitats the fernbird can occasionally be found in areas well away from water, e.g. flax (Phormium tenax), and scrub lands (Moon, 2001). The fernbird can usually be found from sea level to about 1000 metres elevation (Heather and Robertson, 1996).
Preferred habitats
Prior to human settlement of New Zealand the preferred habitat of the fernbird included dense vegetation of wet, swampy areas; for example raupo (Typha orientalis) and flax (Best, 1985). Lake Ellesmere in Canterbury had these preferred wetland habitats (Wilson, 2004). Another feature of preferred habitat is an unbroken canopy at approximately one metre tall (Soper, 1984). However, the preferred habitat of the fernbird have become restricted with extensive draining of wetlands and swamps for agricultural use (Lockley, 1982). The reduction of available habitats had a serve impact on fernbird numbers in Canterbury; it being one of the reasons for it becoming locally extinct (Oliver, 1955).
Phenology/Breeding
Fernbirds predominantly stay near their breeding territories throughout the year. Usually coexisting in small groups or pairs, the onset of spring is accompanied by an increase in the call rate and territorial arguments (Heather and Robertson, 1996). The nest of the fernbird in Canterbury is made of woven grass leaves and 2 or 3 feathers, normally from the Pukeko (Porphyrio melanotus), inside it. The nest is a concealed deep cup and situated most frequently a few inches above the ground in tussock (Oliver, 1955; Soper, 1984). Approximately 3 eggs are laid from late August to January. The eggs are pale pink in colour and usually speckled with purplish, brown flecks. Both of the adults contribute to parental care incubating the eggs for approximately thirteen days and feeding the chicks for roughly seventeen days. The young fernbirds can start reproducing at 9 months old (Heather and Robertson, 1996).
Dispersal
Long evolutionary isolation of the fernbird has resulted in it becoming a poor flyer (Lockley, 1982). The fernbird travels in difficult, short, fluttering trips close to the vegetation. A flight of over 100 metres is outstanding for this small 18cm bird (Best, 1985). Weak flight results in the fernbird being susceptible to the destructive nature of fire. In addition weak flight makes it difficult for the fernbird to disperse to new habitats because it can not simply fly to a new area (Soper, 1972).
Diet
The diet of the fernbird usually consists of invertebrates (Table 1) (Heather and Robertson, 1996). Normally hunting at or above ground level, the fernbird acquires insects from the wetland vegetation (Wilson, 2004). They find their prey by digging in the ground, lifting up leaves, pulling off bark and lunging at flies (Best, 1985).
| Common name | Scientific name |
|---|---|
| Grasshoppers, Wetas and Crickets | Orthoptera |
| Bugs | Hemiptera |
| Bettles | Coleoptera |
| Flies | Diptera |
| Butterflies and Moths | Lepidoptera |
Behaviour
Fernbirds are typically territorial and often disclose their presence in a swamp or scrub by way of their ‘Uu-tick’ call. The fernbird is a secretive but nosey bird, often looking out of vegetation for a moment and then quickly disappearing. They do not fly often but when they do they stay low and close to the vegetation; their tail hanging down peculiarly (Heather and Robertson, 1996).
How to find the Fernbird
There should be no problem identifying the fernbird, even for people with little knowledge of New Zealand native birds. The unique appearance of the fernbird, in particular its fern-like tail, differs from other native New Zealand birds. This appearance along with the “Uu-tick’ call should make distinguishing the fernbird an easy task.
The best time of year to observe the fernbird is usually in the warmer temperatures, of spring and summer. In the cooler temperatures the fernbird seems to lie low in the vegetation and are hard to find (Chambers, 1989). Fernbirds can be lured into view by a playback of its call; as long as the person holding the tape recorder stays still. Any sudden movement will cause the fernbird to retreat as quickly as it appeared (Lockley, 1982).
Abundance and Conservation Status
- New Zealand: moderately abundant
- Canterbury: extinct
In most parts of New Zealand the fernbird has recovered from the cultivation of its natural habitat becoming moderately abundant in most parts. Because of the continued cultivation, and other modern day uses, of most of Canterbury’s swamps and wetlands remains locally extinct (Heather and Robertson, 1996 ).
The fernbird is a protected endemic species. The population fell greatly, as mentioned above, during the time of European settlement. Another threat to the fernbird comes from mammalian predators introduced to New Zealand. As the fernbird spends most of the time on or near the ground it makes an easy target for predation from mammals like dogs (Canis familiaris) and rats (Rattus spp.) (Heather and Robertson, 1996; Oliver, 1955). The fernbird population now seems to be stable, occurring mainly on poor land unsuitable for agricultural use (Heather and Robertson, 1996).
Significance for people
Traditional Maori significance and uses
Regarded as tapu, fernbirds were also offered as a sacrifice when the Maori returned home from an unsuccessful war (Orbell, 2003).
Modern Uses
There is not much that the fernbird can be used for in modern times; other than to observe an endemic and uniquely New Zealand bird. The fernbird is enjoyable to watch with its unique behaviour and appearance.
Summary
The fernbird has a unique behaviour and an appearance that makes it easily distinguished from other native New Zealand birds. It occurs in most parts of New Zealand with a stable population; with the exception of Canterbury where it has become locally extinct. It is a secretive, territorial bird that can be found low in dense vegetation near wetlands. It has a distinctive “Uu-tick” call which it sings in duet with its pair. The fernbird is an interesting and inquisitive bird that is worth observing.
References
Best, H. A. MSc (Hons), (1985). Readers Digest, Complete book of New Zealand birds. Readers Digest Services. New South Wales, Australia.
Chambers, S. (1989). Birds of New Zealand, locality guide. Rice Printers. Hamilton, New Zealand.
Grant, E.A. (1999). An illustrated guide to some New Zealand insect families. Lincoln, New Zealand: Manaaki Whenua Press.
Heather, B. & Roberston, H. (1996). The field guide to the birds of New Zealand. Penguin Books. Auckland, New Zealand.
Lockley, R. and Moon, G. (1982). New Zealand’s birds. Heinmann Publishers, Auckland, New Zealand.
Moon, G. (2001). New Zealand, land of birds. New Holland Publishers, Auckland New Zealand.
Oliver, R. B. (1955). New Zealand birds. A. H. & A. W. Reed, Wellington, New Zealand.
Orbell, M. (2003). Birds of Aotearoa, a natural and cultural history. Reed Publishing, Auckland, New Zealand.
Soper, M. F. (1972). New Zealand birds. Whitcombe & Tombs LTD, Christchurch, New Zealand.
Soper, M. F. (1984). Birds of New Zealand and outlying islands. Whitcoulls Publishers, Christchurch, New Zealand.
Wilson, K-J, (2004). Flight of the Huia. Ecology and conservation of New Zealand’s frogs, reptiles, birds and mammals. University of Canterbury Press, New Zealand.
Search for Bowdleria punctata in New Zealand science online
New Zealand Journal of Ecology articles containing Bowdleria punctata.
Search NZ Royal Society journals for articles containing Bowdleria punctata.
Notornis articles (from the Ornithological Society of New Zealand) containing Bowdleria punctata.
