Morepork

Ninox novaeseelandiae (Gmelin, 1788)

Order: Strigiformes

Family: Strigidae

New Zealand status: Native

Conservation status: Not Threatened

Other names: ruru, boobook, New Zealand owl

Geographical variation: At least 4 subspecies. New Zealand birds are the nominate race N.n. novaeseelandiae; N.n. boobook is common in Australia, where it is known as the boobook owl; N.n. albaria of Lord Howe Island is extinct; N.n. undulata of Norfolk Island is also extinct, surviving only as a hybrid population (with N.n. novaeseelandiae)

Morepork. Adult. Blowhard Bush, Hawke's Bay, December 2012. Image © Adam Clarke by Adam Clarke

Morepork. Adult. Blowhard Bush, Hawke's Bay, December 2012. Image © Adam Clarke by Adam Clarke

The morepork is a small, dark, forest-dwelling owl. Found in both native and plantation forests, its distinctive “more-pork” call is commonly heard at night in many urban parks and well-vegetated suburbs. Moreporks are relatively common throughout much of New Zealand but are sparse through the eastern and central South Island. Their diet consists of insects, small mammals and birds, which it hunts at night.

Identification

The morepork is a small, compact, dark-brown owl. Its striking yellow to yellowish-green eyes are set into two facial disks either side of a small sharply hooked bill. The back feathers are dark-brown spotted sparsely with off-white. The breast is dark-brown variably streaked with cream and brown through to rufous. The legs are feathered legs down to the yellow feet.

Voice: All calls are given only at night. The onomatopoeic ‘more-pork’ call is the most characteristic and often heard call. They also utter a repetitive ‘quork-quork’ and a rising ‘quee’ call.

Similar species: little owls are the only other small species of owl in New Zealand. They are paler than morepork, more grey-brown than dark-brown, and heavily spotted and streaked with cream. They are found only in open habitats in South Island, with minimal range overlap with morepork. The rising ‘quee’ call is often mistaken for a kiwi call.

Distribution and habitat

Moreporks are widely distributed throughout the native and exotic forests of New Zealand. They are uncommon in the drier eastern regions of the South Island, especially south of Christchurch. They also occur in more open areas where suitable patches of vegetation remain including sparsely-wooded farmland, and within some urban parks and gardens. Moreporks inhabit most forested offshore islands from the Three Kings Island south to some of the muttonbird islands off the south-west tip of Stewart Island. They are naturally absent from the Poor Knights Islands and Chatham Islands, and vagrant to the Snares Islands. Moreporks roost in dark forested areas with high overhead cover, on a branch, on top of a tree fern or within cavity. They sometimes roost inside derelict buildings.

Population

Widespread and moderately abundant.

Threats and conservation

Prone to predation when nesting, by cats, possum, rats and mustelids. When nesting on the ground eggs and chicks may also be susceptible to predation by pigs and hedgehogs. Sex bias towards males recorded in the Eglington Valley suggests that females may be vulnerable to predation when incubating and brooding in cavities. Low productivity was recorded in studies in the Eglington Valley (Fiordland) and on Ponui Island (Hauraki Gulf), but the causes are unclear. Moreporks are vulnerable to secondary poisoning from pest control operations using brodifacoum poison. Morepork diet is related to prey abundance, suggesting that the risk of secondary poisoning could be reduced by conducting pest animal control operations at times of year when moreporks are not targeting rodents.

Moreporks breed readily in captivity. Two captive males from New Zealand were released on Norfolk Island in 1987 to provide a mate for the last surviving Norfolk Island boobook owl. This was successful, and the pair produced several young before the female died in the mid 1990s. A hybrid morepork/boobook population persists on Norfolk Island as a result.

Breeding

Moreporks breed in spring and summer. Nests are usually placed within cavities of live or dead trees, within broken logs, in a tree fork or within a hole in earth bank, including in petrel burrows. They also nest in epiphytes, in nest boxes put up for other species, or in a simple scrape on the ground under tree fern fronds, a rock, the roots of trees or anywhere that provides a dark hideaway. The 1-3 eggs are incubated by the female only. Incubation takes about 25 days, and chicks fledge when about 7 weeks old. Both adults feed the young.

Behaviour and ecology

The morepork has short, broad wings making it very manoeuvrable and able to fly through dense forest. Like other owls it has serrated or comb like edges to its flight feathers that reduce air turbulence over the wing, enabling silent flight. Moreporks are most often seen when they are approach street lights or lights on the outside of buildings, to hunt moths that are attracted to the light. They commonly fly into windows, and are often hit by vehicles. Moreporks strongly defend a territory of 3.5 to 7.8 ha. Birds that appear to be calling together in a ‘duet’ are usually rival males duelling.

Food

Moreporks catch and consume a wide variety of small animals, including large insects, small birds, (especially silvereyes), and small mammals. The diet varies with season, generally in proportion to abundance of prey species. Insects taken include huhu beetles, weta, cicadas and large moths. Indigestible material are ejected through the mouth as a pellet.

Weblinks

www.doc.govt.nz/conservation/native-animals/birds/land-birds/morepork-ruru/

www.wingspan.co.nz

www.waikatoregion.govt.nz/Environment/Natural-resources/Biodiversity/Hamilton-Halo/Hamilton-city-morepork-survey/

References

Denny, K.M. 2009. The diet of moreporks (Ninox novaeseelandiae) in relation to prey availability, and their roost site characteristics and breeding success onPonuiIsland,Hauraki Gulf,New Zealand. Unpublished MSc thesis,MasseyUniversity,Albany.

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

Higgins, P. J. (ed.). 1999. Handbook of Australian, New Zealand and Antarctic birds. Vol. 4, parrots to dollarbird. Melbourne,OxfordUniversity Press.

Morgan, D.K.J.; Styche, A. 2012. Results of a community-based acoustic survey of ruru (moreporks) Hamiltoncity. Notornis 59: 123-129.

Olsen, P.D. Re-establishment of an endangered subspecies: the Norfolk Islandboobook owl. Bird Conservation International 6: 63-80.

Pryde, M.; Greene, T.; Dilks, P. 2011. Ruru – what is happening in the darkness? Ecology in the heartland, New Zealand Ecological Society Conference, Rotorua.

Stephenson, B.M.; Minot, E.O. 2006. Breeding biology of Morepork (Ninox novaeseelandiae) on Mokoia Island, Rotorua, New Zealand. Notornis 53: 308-315.

Stephenson, B.M.; Minot, E.O.; Armstrong, D.P. 1999. Fate of moreporks (Ninox novaeseelandiae) during a pest control operation on Mokoia Island, Lake Rotorua, North Island, New Zealand. New Zealand Journal of Ecology 23: 233-240.

Recommended citation

Seaton, R.; Hyde, N. 2013. Morepork. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Morepork

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

Morepork

Social structure
monogamous
Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Nest type
burrow, scrape, tree hole
Nest description
Within cavities of live or dead trees, within broken logs, in tree fork or within a hole in earth bank, including in petrel burrows. Also nest in epiphytes, in nest boxes put up for species such as starlings and saddlebacks or in a simple scrape on ground under tree fern fronds, a rock, the roots of trees or anywhere that provides a dark hideaway.
Nest height (mean)
3.40 m
Nest height (min)
0.00 m
Nest height (max)
12.00 m
Maximum number of successful broods
Unknown
Clutch size (mean)
2
Clutch size (min)
1
Clutch size (max)
5
Mean egg dimensions (length)
38.00 mm
Mean egg dimensions (width)
33.99 mm
Egg colour
White
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Interval between eggs in a clutch
2 days
Incubation behaviour
female only
Incubation length (mean)
Unknown
Incubation length (min)
20days
Incubation length (max)
30days
Nestling type
altricial
Nestling period (mean)
About 35 days
Nestling period (max)
40days
Age at fledging (mean)
About 35 days
Age at fledging (max)
40days
Age at independence (mean)
91 days
Age at first breeding (typical)
Unknown
Age at first breeding (min)
1years
Maximum longevity
Approximately 6 years
Maximum dispersal
377 km