Reports and Publications about riflemen

[Dave Houston]

Append details of reports and publications regarding riflemen to this thread

[Dave Houston]

Sherley, GH (1990).  Co-operative Breeding in riflemen - benefits to parents, offspring and helpers.  Behaviour 112: 1-22.

Two types of helpers were observed feeding young of New Zealand riflemen: "regulars" and "casuals".  The former contributed significantly to feeding young from only one nest while the latter contributed a trivial amount to young from a number of nests.  regulars were usually unpaired adult males some of which acquired a mate from the brood they helped.  While some casuals were unpaired adult males, most were current season offspring helping with their parents second clutch.  The relative contribution of parents and helpers in raising broods were measured to establish the benefits of co-operative breeding to offspring and feeders.  Whether or not helpers were present while feeding young, the breeding females contribution was the same.  By contrast, the work load of the breeding male was significantly reduced when helpers were present, but even then he contributed more than his mate.  That male parents benefited most from helpers feeding young was probably related to their being responsible for most of teh feeding in the absence of helpers.  A helpers presence did not improve productivity or the male parents chance of survival.  However, female parents of nests with regular helpers survived better than thos ewithout.  Offspring fed by helpers were not heavier upon fledging nor were their chances of survival improved.  The interval between fledging first clutch broods and laying second clutches was the same whether helpers were present or not.

[Dave Houston]

Gray RS (1969).  Breeding Biology of Riflemen at Dunedin.  Notornis 16: 5-22

Nest boxes were used to study the nesting cycle of Rifleman in second-growth bush near Dunedin city.  During three nesting seasons, two to five territories were studied.  It was found that the incubation period was 20-21 days; the nestling period was about 24 days; there was an interval of about 48 hours between successive eggs of a clutch; and clutches known to be complete varied from 2-4 eggs.  No pair raised more than two clutches per season, though several pairs built or at least started more than two nests.  Losses occured mostly during the building and agg stages and were generally due to abandonment for reasons unknown.  In only one nest were fledglings lost, and this was due to human interference, which would probably not have occurred if the nest had been in a natural site.

[Dave Houston]

Leech, T.J., Craig, E., Beaven, B., Mitchell, D.K., and Seddon, P.J..  (2007). Reintroduction of rifleman Acanthisitta chloris to Ulva Island, New Zealand: Evaluation of techniques and population persistence. Oryx, 41(3), 369-375.

Rifleman, or titipounamu Acanthisitta chloris, is New Zealand’s smallest endemic passerine. The species has a fragmented distribution and is threatened in the Rakiura region in the south of the South Island. The only known population of South Island rifleman A. c. chloris in the Rakiura region persisted on Codfish Island/Whenua Hou. To create a second population of rifleman in Rakiura, 30 caught from Codfish Island were reintroduced onto nearby Ulva Island in February 2003, the first translocation of rifleman. Survival and dispersal were monitored for 1 month post-release, and subsequently during the first and second breeding seasons.

Mortality was greatest during holding and transfer, with low to moderate post-release mortality. All founding pairs bred in the first breeding season, and both founders and offspring bred in the second season. Dispersal across the island was greater for offspring. A simple deterministic matrix model indicated positive annual population growth (k 5 1.33), and low risk of short-term extinction.

Holding/transfer techniques should be improved for future reintroductions, and longer-term monitoring should be undertaken for a more accurate assessment of vital rates. Based on the survival of founding birds, reproduction by the release generation and their offspring, and high probability of population persistence, the rifleman reintroduction was considered to be successful and a good model for future reintroductions of small passerine birds.

Full text of paper available here :  http://tinyurl.com/2bynzg

[Dave Houston]

Moeed A & Fitzgerald BM (1982).  Foods of insectivorous birds in forest of the Orongorongo Valley, Wellington, New Zealand.  New Zealand Journal of Zoology, Vol 9: 391-402.

Foods are described from analysis of faeces and castings of adult riflemen and a number of other species, inhabiting indigenous forest in the North Island of New Zealand.  Beetles, spiders, and caterpillars were important to all 6 species.  Differences in diet are shown to be related to the birds feeding habits.  Information is given on the seasonal distribution and abundance of some invertebrate foods.  Seasonal changes in diet were small, probably reflecting the rather equable oceanic climate of New Zealand, where invertebrates are available throughout the year.  Fruits and other vegetable matter were shown to occur to a varying extent in the diet of all 6 species.

[Dave Houston]

Gaze, P.D. (1978). Breeding Biology of the North Island Rifleman.  In: Abtract of AGM Talks: New Zealand Passerines.  Notornis 25: 244.

The breeding biology of the NI rifleman was studied in the Orongorongo Valley 1973-1976.  50-200 nest boxes were available each year and between one and eight were used each season.  Breeding began in late September, with an average clutch of 4.5 eggs, the eggs being laid on alternate days.  The eggs which weighed 22% of the adult weight were incubated for 19-20 days and the young stayed in the nest 21-27 days.  During the first three years 77% of 53 eggs laid resulted in fledged young, but in 1976 only 30% were successful.  Chick growth is also discussed.

[Dave Houston]

Sherley, G.  Benefits of courtship-feeding for rifleman (Acanthisitta chloris) parents.  Behaviour. Vol. 109, no. 3-4, pp. 303-318. 1989.

Courtship-feeding was studied in riflemen (Acanthisitta chloris) in a population at Kaikoura, South Island, New Zealand between 1982 and 1984. Copulation attempts did not correspond with bouts courtship-feeding or the peak of courtship-feeding. Food items delivered in courtship-feeding were significantly larger than those eaten by males or females while foraging for themselves, and larger food items were consistently offered throughout the pre-laying and egg-laying periods. Overall the male contributed 42% of the food he gathered to the female and this comprised 35% of her total food intake.

[Dave Houston]

Sherley, G.  Relative parental effort during incubation in riflemen (Acanthisitta chloris).  New Zealand Journal of Zoology [N.Z. J. ZOOL.]. Vol. 17, no. 3, pp. 289-294. 1990.

The incubation system of riflemen was studied from 1980 to 1984 at Kowhai Bush, Kaikoura, New Zealand. Their nests are designed to maximise thermal insulation. So too is their behaviour, e.g., covering eggs and blocking the nest entrance with feathers. The outstanding feature of rifleman incubation is that males incubated for 48% and 45% of the time during first and second clutches, respectively, whereas the corresponding figures for females were both 33%. Hence females had about two more hours of daylight available for foraging than males. The difference in time spent incubating was because of longer incubation spells of males, rather than a higher frequency of visits to the nest. At night, females incubated while males roosted near the nest. The temperature inside the nest at night averaged 15 degree C and 12 degree C higher than that outside for first and second clutches, respectively. Riflemen have a highly co-operative parental care system during incubation which probably allows females to recoup condition after the expenditure of energy involved in laying a large clutch weight relative to the female's body weight.

[Dave Houston]

Lill, A.  Behavioural energetics of overwintering in the Rifleman, Acanthisitta chloris.  Australian Journal of Zoology [AUST. J. ZOOL.]. Vol. 39, no. 6, pp. 643-654. 1991.

Rifleman foraged for 83% of daytime in both seasons. The combined effects on the birds' winter energy budget of increased thermoregulation costs and the shorter daylength for foraging were at least partly offset by an estimated 23-29% decrease in the amount of energy expended daily on activity and a 78% increment in prey caught per day. The reduced energy expenditure on activity resulted from rifleman spending less time on expensive flying and more time roosting. The increase in prey capture rate may have stemmed from a 35% seasonal reduction in the birds' population density and reduced prey mobility at lower ambient temperatures. Marked sexual size dimorphism was not reflected in gender differences in activity budgeting or prey capture rate, but the sexes differed in their relative use of foraging substrates.

[Dave Houston]

Sherley, GH.  Parental investment, size sexual dimorphism, and sex ratio in the rifleman (Acanthisitta chloris) New Zealand Journal of Zoology [N.Z. J. ZOOL.]. Vol. 20, no. 3, pp. 211-217. 1993.

R. A. Fisher in 1958 related primary sex ratio to parental investment in young by predicting that, if one sex was larger, then the higher investment in that sex would be offset by an adjustment in the primary sex ratio in favour of the smaller sex. Larger females in the rifleman (Acanthisitta chloris) provided a prima facae test case for Fisher's theory. While females seemed most costly to rear, there was no significant difference in survival or in numbers that bred in the years following fledging. Parent survival was not affected by rearing more females than males. The sex ratio of both chicks and unhatched eggs was near unity. I conclude that Fisher's theory is not sufficient explanation of the relationship between size sexual dimorphism, primary sex ratio, and the value of each sex to parents.

[Dave Houston]

Hunt, GR; McLean, IG. The ecomorphology of sexual dimorphism in the New Zealand rifleman Acanthisitta chloris .Emu. Vol. 93, no. 2, pp. 71-78. 1993.

New Zealand Rifleman Acanthisitta chloris females are larger and browner than males (which are green dorsally), have a relatively larger hind claw and a longer, more decurved bill. Using three criteria for distinguishing sexual selection from ecological influences on sexual dimorphism, we suggest that sexual dimorphism in the Rifleman is maintained by ecological factors. When energy requirements were high (feeding fledglings), female and male Rifleman foraged separately. When energy requirements were low (non-breeding), females and males fed together. Plumage differences between the sexes were correlated with the different habitats in which Riflemen foraged when energy demands were high.

[Dave Houston]

Beaven, B.  Transfer report on translocation of riflemen (Titipounamu; Acanthisitta chloris) from Whenua Hou / Codfish Island to Ulva Island on 10th to 14th February 2003.  Sponsored by the New Zealand National Parks and Conservation Foundation in association with Transpower.  Internal DOC report.

30 riflemen were transferred from Whenua Hou / Codfish Island to Ulva Island in February 2003.  A total of 60 birds were caught, but 50% of birds caught died before release on Ulva.  Only 18 birds could be located on Ulva Island one month after release.  The report outlines lessons learnt and recommendations to reduce mortality for future releases.  Birds did not disperse far from the release site (average 112m); had a home range of 2.15ha.  67% of pairs were newly established post release.