Spotless crake

Porzana tabuensis (Gmelin, 1789)

Order: Gruiformes

Family: Rallidae

New Zealand status: Native

Conservation status: Relict

Other names: sooty rail, pūweto, puweto, putoto

Geographical variation: New Zealand populations are included in the nominate subspecies tabuensis, ranging from the Philippines to south-west Polynesia, including Australia and New Zealand. Two other subspecies have been named from the highlands of New Guinea.

Spotless crake. Adult in open. Tiritiri Matangi Island, February 2012. Image © Martin Sanders by Martin Sanders  http://martinsanders.smugmug.com/ 

Spotless crake. Adult in open. Tiritiri Matangi Island, February 2012. Image © Martin Sanders by Martin Sanders  http://martinsanders.smugmug.com/ 

The spotless crake is a cryptic bird of freshwater wetlands throughout the North Island. It is a small, dark coloured rail (about half the size of a Eurasian blackbird) that is very secretive and infrequently seen. Their furtive nature and good dispersal ability mean that they could be present in areas of suitable habitat far from known populations.

Identification

The spotless crake is a small dark rail. The plumage is dark brown on the upper parts and dark bluish grey beneath. The stout bill is black. The legs are orange-pink and the bright red eyes contrast sharply with the dark head. Juveniles are duller with a pale chin and throat and dark legs.

Voice: heard more often than seen. Several different calls are given, including bubbling sounds, a short 'pit-pit', a repeated 'mook' and the loudest call, a long trilling 'purr'.

Similar species: spotless crake are similar in size and shape to a marsh crake, however marsh crakes are much more strikingly patterned. It is possible that calls of unseen birds could be confused.

Distribution and habitat

Spotless crakes are widely if patchily distributed throughout the North Island, but are rare in the South Island. They are present on Raoul Island and the adjacent Meyer Islets (Kermadec Islands), and Great Barrier, Three Kings, Poor Knights, Tiritiri Matangi and Motuora Islands. There are no confirmed records from the Chatham Islands since 1949.

On the mainland the spotless crake is predominantly a bird of freshwater wetlands dominated by dense emergent vegetation, particularly raupo (Typha orientalis). They may forage on open mud near dense vegetation but are quick to retreat when disturbed. Spotless crakes live in dry forest on some islands, including the Kermadec Islands, Poor Knights, Tiritiri Matangi and Motuora.

Population

No population estimates available. Fewer than 50 adults were estimated to be present on Aorangi in 1980, where the smallest territory was 45 x 50 metres, or approximately 4 pairs per ha.

Threats and conservation

Habitat loss through destruction of the vast majority of lowland wetlands for agriculture is presumed to have had a significant impact on spotless crakes. It was given the conservation status of Relict (i.e. occupying less than 10% of its original range) due to more than 90% of New Zealand’s wetlands having been converted to farmland and towns. Introduced predators are likely to prey on crakes. The presence of spotless crakes in dry forest on predator-free islands suggests they may have formerly used a wider range of habitats.

Breeding

Spotless crakes are monogamous and territorial. When nesting in wetlands, the nest of woven grass and sedge leaves is raised 30–50 cm above water level, often in a clump of Carex sedge. Several nest-like platforms are often built near the actual nest. The clutch of 2–5 cream coloured eggs is laid from late August to January and incubated by both parents for 20–22 days. The chicks remain in the nest for up to 4 days and are cared for by both parents for 4–5 months. Chicks are capable of catching live prey from 3 days old.

Behaviour and ecology

Very secretive and largely crepuscular. Spotless crakes seldom venture far from the cover of vegetation during daylight. Pairs and some single birds defend territories. Parents may feign injury to distract predators.

Food

Spotless crakes have a broad omnivorous diet, feeding on seeds, fruit and leaves of aquatic plants, and a wide variety of invertebrates including worms, snails, spiders, beetles and other insects.

References

Heather, B.; Robertson H. 1996. The field guide to the birds of New New Zealand. Viking: Auckland.

Miskelly, C.M.; Bester, A.J.; Bell, M. 2006. Additions to the Chatham Islands' bird list, with further records of vagrant and colonising bird species. Notornis 53: 215-230.

Kaufmann, G.; Lavers, R. 1987. Observations of breeding behaviour of spotless crake (Porzana tabuensis) and marsh crake (P. pusilla) at Pukepuke Lagoon. Notornis 34: 193–205.

Marchant, S.; Higgins, P.J. (eds.) 1993. Handbook of Australian, New Zealand and Antarctic birds. Vol. 2, raptors to lapwings. Oxford University Press, Melbourne.

O'Donnell, C.F.J. 1994. Distribution and habitats of spotless crakes in Canterbury. Notornis 41: 211-213.

Onley, D.J. 1982. The spotless crake (Porzana tabuensis) on Aorangi, Poor Knights Islands. Notornis 29: 9-21

Williams, M.J. 1985 Spotless crake. In Robertson, C.J.R. (ed.) Readers Digest complete book of New Zealand Birds. Readers Digest: Sydney.

Recommended citation

Fitzgerald, N. 2013. Spotless crake. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Spotless crake

Social structure
monogamous
Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Nest type
woven cup
Nest description
Woven cup of grass and sedge leaves.
Nest height (min)
0 m
Nest height (max)
0.5 m
Maximum number of successful broods
2
Clutch size (mean)
2-5
Clutch size (min)
2
Clutch size (max)
5
Mean egg dimensions (length)
30 mm
Mean egg dimensions (width)
22 mm
Egg colour
Dull creamy-brown or pinkish with faint chestnut flecks
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Interval between eggs in a clutch
24 hours days
Incubation behaviour
shared
Incubation length (mean)
20-22 days
Incubation length (min)
20 days
Incubation length (max)
22 days
Nestling type
semi-precocial
Nestling period (mean)
Up to 4 days
Age at fledging (mean)
Unknown
Age at independence (mean)
4-5 months
Age at first breeding (typical)
Unknown
Maximum longevity
Unknown
Maximum dispersal
Unknown

Spotless crake

Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun