Rifleman

Acanthisitta chloris (Sparrman, 1787)

New Zealand status: Endemic

Conservation status: Declining

Other names: tītipounamu, titipounamu

Geographical variation: Two sub-species, both extant.  North Island rifleman A. c. granti (At Risk/Declining), South Island rifleman A. c. chloris (At Risk/Declining)

Rifleman. Adult male South Island rifleman. . Image © Department of Conservation (image ref: 10029849) by Mike Soper, Department of Conservation Courtesy of Department of Conservation

Rifleman. Adult male South Island rifleman. . Image © Department of Conservation (image ref: 10029849) by Mike Soper, Department of Conservation Courtesy of Department of Conservation

The rifleman is generally considered to be New Zealand’s smallest bird (the equally light-weight grey warbler has a longer tail). It is one of only two surviving species within the ancient endemic New Zealand wren family. Riflemen are small forest-dwelling insectivores, and are constantly on the move, producing a characteristic ‘wing-flicking’ while moving through the canopy and foraging up and down tree trunks. South Island riflemen are found throughout forests of the main divide, but are less common in the east of the South Island, and extinct on Stewart Island (apart from Codfish and Ulva Islands). North Island riflemen survives as geographically isolated populations on North Island mountain ranges, with only three populations north of Pureora Forest (Warawara Forest in Northland, and on Little Barrier and Tiritiri Matangi Islands).

Identification

Riflemen are sexually dimorphic. Males are smaller than females and have a bright green on the head and back. Females are mainly yellow-brown with darker speckles on the head and back. Both sexes have pale grey under-parts. The black bill is slender, pointed, and angled slightly upwards. Riflemen are very small birds with short wings and a very short tail and forage predominantly within the canopy and on tree-trunks.

Voice: a short, simple, high frequency zip, pip or chuck produced by both sexes. The alarm call is a rapid high frequency decrescendo. Riflemen utter almost constant contact calls while foraging. Calls are produced at a high frequency often inaudible to people.

Similar species: rock wren (South Island alpine areas only) is larger, with longer legs and a stouter bill that is not upturned.

Distribution and habitat

Riflemen are found predominantly in mature forest, especially beech, kauri, kamahi and podocarp forest. They are now mainly confined to higher altitude forest throughout both the North and South Islands. Their distribution in the North Island is patchy, including throughout the eastern ranges south to the Rimutaka range and on the Central Plateau (including Pureora Forest Park and Tongariro National Park). Remnant populations are present in Warawara Forest (Northland), on Little Barrier Island and in Mount Egmont National Park. Riflemen are widespread throughout the west of the South Island, and also occur on Banks Peninsula and in the seaward Kaikoura ranges. They are recently extinct on Stewart, but survive on Codfish Island. Riflemen have been translocated to Ulva Island, Stewart Island, Cape Kidnappers and Tiritiri Matangi Island.

Population

Riflemen occur at high densities throughout the eastern ranges of the North Island (e.g. Urewera, Kaweka and Tararua ranges), and at lower densities in other remnant populations around the North Island. They are locally common in Nelson and in Marlborough and relatively widespread through the west of the South Island but in lower numbers in the east of the South Island.

Threats and conservation

Population declines and fragmentation of riflemen are considered likely to be related to habitat clearance initially, compounded by the impacts of introduced pest species, particularly stoats.

Breeding

Riflemen breed from August through to February. They build enclosed spherical nests within existing cavities. A diverse range of cavity types are used for nesting. Pairs can raise up to two broods per season, with more attempted if any nests fail. The males does most of the nest building, and both sexes contribute to incubation, nestling and fledgling care. Incubation of the 2-5 eggs takes about 20 days, and chicks leave the nest when about 24 days old. Riflemen breed in cooperative family groups in both sub-species, where related offspring help to raise siblings from subsequent clutches. Unrelated helpers may also assist with breeding and are thought to gain pairing opportunities from helping.

Behaviour and ecology

Riflemen are relatively poor flyers with limited dispersal capability. They typically move through the forest using short flights, mainly from canopy to canopy. The majority of time is spent foraging for small insects in the canopy or on tree trunks; in the absence of introduced predators, riflemen also forage on the ground. They use a variety of foraging behaviours including probing beneath bark on the trunks of trees, gleaning from leaves and branches, and are infrequently seen to aerial forage. Riflemen are monogamous species with long-term pair-bonds, only replacing a mate if one of the pair dies. Mates forage in close proximity throughout the year, keeping in contact using frequent calls. Breeding appears to be initiated by male nest-building behaviour. Males contribute substantially to the parental effort including nuptial feeding, nest building, and a share of incubation, and nestling and fledgling care. Riflemen are often seen in cooperative family groups which raise broods together. Helpers contribute to feeding of nestlings but not to incubation or nest-building. Loose territories are occupied but are rarely aggressively defended. Territory boundaries appear to be loosely defined with no vocal or behavioural advertisement of boundaries and neighbour intrusions largely tolerated.

Food

Riflemen are exclusively insectivorous, feeding on a large variety of small invertebrates, particularly beetles, spiders and moth species (both adults and caterpillars).

Weblinks

http://en.wikipedia.org/wiki/Rifleman_(bird)

http://www.teara.govt.nz/en/small-forest-birds/page-2

http://www.nzbirds.com/birds/titipounamu.html

References

Cooper, A. 1994. Ancient DNA sequences reveal unsuspected phylogenetic relationships within New Zealand wrens (Acanthisittidae). Experientia 50: 558-563.

Elliott, G.P.; Wilson, P.R.; Taylor, R.H.; Beggs, J.R. 2010. Declines in common, widespread native birds in a mature temperate forest. Biological Conservation 143: 2119-2126.

Ericson, P.G.P.; Christidis, L.; Cooper, A.; Irestedt, M.; Jackson, J.; Johansson, U.S.; Norman, J.A. 2002. A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens. Proc. R. Soc. Lond. B 269(1488): 235-241.

Ericson, P.G.P.; Irestedt, M.; Johansson, U.S. 2003. Evolution, biogeography, and patterns of diversification in passerine birds. Journal of Avian Biology 34: 3-15.

Gaze, P. D. 1978. Annual General Meeting Report: breeding biology of the North Island rifleman. Notornis 25: 244.

Gill, B. J. 1996. A fossil bone of the rifleman (Acanthisitta chloris) from Cape Reinga. Notornis 43: 113-114.

Gray, R. S. 1969. Breeding biology of rifleman at Dunedin. Notornis 16: 5-22.

Harper, G.A. 2009. The native forest birds of Stewart Island/Rakiura: patterns of recent declines and extinctions. Notornis 56: 63-81.

Higgins, P.J.; Peter, J.M.; Steele, W.K. (eds) 2001. Handbook of Australian, New Zealand and Antarctic birds. Vol. 5, tyrant-flycatchers to chats. Oxford University Press, Melbourne.

Hunt, G.R.; McLean, I.G. 1993. The ecomorphology of sexual dimorphism in the New Zealand rifleman Acanthisitta chloris. Emu 93: 71-78.

Leech, T.; Craig, E.; Beaven, B.; Mitchell, D.K.; Seddon, P.J. 2007. Reintroduction of rifleman Acanthisitta chloris to Ulva Island, New Zealand: evalution of techniques and population persistence. Oryx 41: 369-375.

Lill, A. 1991. Behavioural energetics of overwintering in the rifleman Acanthisitta chloris. Australian Journal of Zoology 39: 643-654.

Miskelly, C.M.; Powlesland, R.G. 2013. Conservation translocations of New Zealand birds, 1863-2012. Notornis 60: 3-28.

Pierce, R. J. 1994. A relict population of rifleman in Northland. Notornis 41: 234.

Sherley, G. 1985. The breeding system of the South Island rifleman at Kowhai Bush, Kaikoura, New Zealand. PhD thesis, University of Canterbury, Christchurch.

Sherley, G. 1993. Parental investment, size sexual dimorphism, and sex ratio in the rifleman (Acanthisitta chloris). New Zealand Journal of Zoology 20: 211-217.

Sherley, G. 1994. Co-operative parental care; contribution of the male rifleman (Acanthisitta chloris) to the breeding effort. Notornis 41: 71-81.

Sherley, G. H. 1990. Co-operative breeding in rifleman (Acanthisitta chloris): benefits to parents, offspring and helpers. Behaviour 112: 1-22.

Sibley, C.G.; Williams, G.R.; Ahlquist, J.E. 1982. The relationships of the New Zealand wrens (Acanthisittidae) as indicated by DNA-DNA hybridization. Notornis 29: 113-130.

Withers, S. 2009. Observations of bellbird (Anthornis melanura) aggression toward North Island rifleman (Acanthisitta chloris granti) in a translocated population. Notornis 56: 44-45.

Recommended citation

Withers, S. 2013. Rifleman. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Rifleman

Social structure
co-operative breeding groups
Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Nest type
burrow, enclosed dome, ground-level hollow, hole in building, rock crevice, tree hole
Nest description
Enclosed dome made predominantly of leaf skeletons and lined with feathers, situated within a cavity. Occasionally built without a cavity as an enclosed spherical nest on tree branches.
Nest height (min)
0 m
Nest height (max)
10 m
Maximum number of successful broods
2
Clutch size (mean)
3.5
Clutch size (min)
2
Clutch size (max)
5
Mean egg dimensions (length)
15.9 mm
Mean egg dimensions (width)
12.5 mm
Egg colour
White slighhtly glossy
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Interval between eggs in a clutch
48 hours days
Incubation behaviour
shared
Incubation length (mean)
20 days
Incubation length (min)
19 days
Incubation length (max)
21 days
Nestling type
precocial
Nestling period (mean)
24 days
Nestling period (min)
24 days
Nestling period (max)
25 days
Age at fledging (mean)
24 days
Age at fledging (min)
24 days
Age at fledging (max)
25 days
Age at independence (min)
52 days
Age at independence (max)
66 days
Age at first breeding (typical)
0.5 years
Maximum longevity
6 years
Maximum dispersal
1.7 km

North Island rifleman

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

South Island rifleman

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