Gallirallus Australis Research Articles

Evaluation of secondary poisoning hazards to ferrets and weka from the rodenticide coumatetralyl

We investigated the secondary poisoning hazards of the rodenticide coumatetralyl to a predatory and scavenging mammal and bird. Wistar rats, which had been poisoned with Racumin® baits containing 375 ppm coumatetralyl, were fed to 10 captive ferrets (Mustela furo) and 10 weka (Gallirallus australis) for 3 consecutive days. Nine ferrets ate 764 ± 95 g kg–1 (83% by weight) of the rat carcasses offered and two died. Weka ate 258 ± 32 g kg–1 (25% by weight) of the rat carcasses, preferring the internal organs. There were no deaths and no obvious signs of ill health in any weka. These results suggest that predatory and scavenging bird and mammal species, in general, will be placed only at comparatively low risk from secondary poisoning from coumatetralyl.

Avifaunal changes revealed in Quaternary deposits near Waitomo Caves, North Island, New Zealand

Late Pleistocene (23 000–10 000 14C yr BP) and Holocene (10 000 14C yr – present BP) avifaunas are described from the Henry Lambert and associated passages in Gardners Gut Cave, Waitomo Caves, North Island, New Zealand. Nine radiocarbon dates on bones and three uranium series dates on speleothems support the dating of the sites. These data are augmented by six new dates and reanalysis of the avifaunas from F1c Cave, also in the Waitomo karst. A distinctive Pleistocene avifauna characterised by the moa Euryapteryx curtus and Pachyornis mappini and the North Island goose (Cnemiornis gracilis) with common associates including New Zealand coot (Fulica prisca), North Island takahe (Porphyrio mantelli), Finsch's duck (Euryanas finschi), and North Island kokako (Callaeas wilsoni) was present. The presence of kokako, saddleback (Philesturnus rufusater), and robin (Petroica longipes) in the Pleistocene deposits and the absence of grassland taxa such as pipit (Anthus novaeseelandiae) and quail (Coturnix novaezelandiae) indicate that the vegetation about Gardners Gut Cave included tall shrubland and probably lacked much grassland, even over the Last Glacial Maximum. The Holocene at Waitomo was characterised by a moa fauna dominated by Anomalopteryx didiformis, although both Euryapteryx curtus and Pachyornis mappini persisted in small numbers. The frequent occurrence of kakapo (Strigops habroptilus), weka (Gallirallus australis), and brown teal (Anas chlorotis) typifies Holocene avifaunas; Cnemiornis and Fulica are unknown from Holocene deposits in the area.

Assessment of risks of brodifacoum to non-target birds and mammals in New Zealand.

The risks to non-target birds and other wildlife from the use of vertebrate pesticides, including anticoagulant rodenticides, are determined to a significant extent by species' intrinsic susceptibility, and the toxicokinetics of the compounds used. Brodifacoum is highly toxic to birds and mammals. The acute toxicity of brodifacoum to birds in New Zealand varies from <1 mg/kg in pukeko (Porphyrio p. melanotus), the native swamp hen, to >20 mg/kg in the paradise shelduck (Tadorna variegata). Like other second-generation anticoagulants brodifacoum is strongly bound to vitamin K epoxide reductase and will persist, apparently for at least 6 months, in organs and tissue containing this enzyme, e.g., liver, kidney, and pancreas. The unique toxicokinetics of this class of compound exacerbates the risk of primary and secondary poisoning of non-target species. Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko, weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals. There are increasing numbers of reports worldwide of wildlife contamination and toxicosis after the use of second-generation anticoagulants. All pest control activities require careful risk-benefit assessment in view of their potential to cause adverse environmental impact. Monitoring of wildlife for pesticide residues will provide data that can be used to reduce the risk of anticoagulant bioaccumulation and mortality in non-target species.

Review of ecological restoration programme on subantarctic Macquarie Island: Pest management progress and future directions

Summary The establishment of exotic species of vascular flora and vertebrate fauna on subantarctic Macquarie Island since its discovery in 1810 has resulted in major changes in the biota. A management programme aims to reduce the numbers of exotic plant and animal species and assist with the recovery of pre‐existing communities and processes. This paper reviews the integrated vertebrate pests management programme on Macquarie Island since 1974 and outlines future management considerations. As part of this programme, the responses of some native and exotic species of vascular flora and vertebrate fauna were monitored following control of European Rabbit (Oryctolagus cuniculus) numbers. Changes in the vegetation recorded over 10 years showed that approximately half of all the vascular species had benefited from rabbit grazing, including several which formed a major part of the rabbit’s diet. After rabbit control, some adversely affected plants responded rapidly to a reduction in grazing pressure while others will require an almost total cessation of grazing in order to re‐establish their former distributions. With the decrease in rabbit numbers it was also necessary to control Feral Cats (Felis catus) due to their increased predation on native burrow‐nesting birds. Feral Cat predation on introduced fauna also increased, one result of which was the eradication from the island of the introduced Weka (Gallirallus australis scotti). Reduced rabbit grazing is leading to re‐establishment of the native Tall Tussock (Poa foliosa) grassland and with it the spread of the introduced Ship Rat (Rattus rattus). This review indicates that an integrated approach to pest management, with monitoring of the responses of both target and non‐target species, is the most effective way to restore pre‐existing communities and processes.Key words grazing pressure, introduced species, predation, recovery, vertebrate pest management.

Directions for future management of North Island Weka Gallirallus australis greyi to improve survival and productivity in situ

We investigated how North Island Weka Gallirallus australis greyi could be conserved in situ at East Cape, New Zealand using banded and radiotransmitter-carrying Weka to measure home range size and use, reproduction and mortality. We fitted radiotransmitters to 28 Weka with 75% of the subsequent fixes from 18 birds being obtained at intervals of &lt; 4 days. Home ranges of 10 males had an estimated median size of 10.6 ha, while 5 female home ranges had an estimated median size of 3.5 ha. Home ranges of individuals of both sexes overlapped. Within their home ranges, Weka preferred bush relative to pasture and may have preferred pines to pasture. Weka did not significantly prefer bush to pines. Breeding occurred year-round, with a summer peak, but 11 breeding pairs raised only four chicks to independence in two years. The causes of egg and chick mortality could not be established, but predators killed six adults, motor vehicles killed six and one adult died in a trap. Measurements of body size revealed that a male-biased sex ratio was likely (67:33). We concluded that the recovery of the North Island Weka population in the East Cape region will require improving reproductive success and decreasing predation on adults. We recommend that managers focus on predator removal and habitat creation in future.

Colour preferences and coloured bait consumption by weka Gallirallus australis, an endemic New Zealand rail

Native birds are among the non-target species that are killed in poisoning operations directed at introduced mammalian pests in New Zealand. By identifying colours that birds find unattractive, and incorporating them into poisonous baits, some deaths may be avoided. The colour preferences of weka, Gallirallus australis, an endemic New Zealand rail, were tested over 6 days by offering individual weka a choice between six different colours of a novel food pellet. Weka ate significantly more red and yellow pellets on the first day than green, mid-blue, light-blue, or brown pellets but consumption of all colours increased sharply on subsequent days. The colour preferences found agree well with published studies on other bird species. If colour preferences are general across species colour may be useful in deterring birds from poisonous baits. Weka however with their opportunistic and adaptable feeding style rapidly increased their consumption of baits, even those colours they initially avoided. It appears that a more active deterrent than colour will be needed for weka.

Comparison of the capture efficiency of a kill‐trap set for brushtail possums that excludes ground‐birds, and ground set leg‐hold traps

Ground‐set leg‐hold traps are commonly used in New Zealand to catch possums (Trichosurus vulpecula), both for control, and to monitor success of control operations. These sets have occasionally caught kiwi (Apteryx spp.) and weka (Gallirallus australis), so the Department of Conservation now requires that all traps set on conservation land be placed 70 cm above the ground in areas inhabited by these species. To set leg‐hold traps at this height requires the use of platforms or boards, which reduce trapper efficiency, and longer trap chains, which increase the chance of the captured possums injuring themselves. An alternative approach, which has the potential to improve trapper efficiency and address the animal welfare concerns, is to use kill traps set at least 70 cm above the ground. Tree‐trunk‐set kill traps (BMI 160) were compared with ground‐set Victor No 1 unpadded leg‐hold traps. In the first two trials, BMI traps set with plastic cubbies (161 possums/432 trap nights) recorded capture efficiencies significantly less than those achieved using the Victor traps (215 possums/432 trap nights). In trials with more rigid wooden cubbies, the capture efficiency of BMI (218 possums/480 trap nights) and Victor traps (224 possums/480 trap nights) were not significantly different. Of the 379 possums caught in the BMI traps, 367 (97%) were struck in the head or neck (the desired target location for a humane kill), and 98% were killed. Results from these trials indicate that if BMI traps are left for three or more nights between checks, their capture efficiency will be greater than that achieved for Victor leg‐hold traps that must be checked every day. We conclude that there are kill traps that can be used effectively for killing possums, which eliminate the risk of traps to ground‐dwelling birds, and will thus help reduce our reliance on the use of leg‐hold traps.

Quaternary fossil faunas of Otago, South Island, New Zealand

The Quaternary terrestrial faunas, primarily birds, of three inland districts in Otago, South Island, New Zealand are described. The three areas (North Otago, Central Otago and near Wanaka) differ in their present topography and climate, and their palaeofaunas are also different: that of North Otago is considerably more diverse than either of the others. The differences are related to habitat diversity and climate. In Otago, 62 native species of birds, plus greater and lesser short‐tailed bats Mystacina spp., tuatara Sphenodon, Duvaucel's gecko Hoplodactylus duvaucelii, common gecko H. maculatus, and indeterminate skinks Oligosoma spp, are recorded from fossil deposits. Most deposits are of Holocene age. Swamp‐miring, predation by laughing owls and falcons, and pitfall processes were responsible for accumulating the fossils. The holotype of Ocydromus insignis Forbes is identified, and the species synonymised with Gallirallus australis Sparrman.

Failure of translocated, captive-bred North Island Weka Gallirallus australis greyi to establish a new population

SummarySince i960 107 translocations of wild-caught Weka (genus Gallirallus) have occurred in New Zealand. Only four of these Weka liberations resulted in a population that persisted for more than 10 years and only one was successful on the North Island (the resultant population is now believed extinct). The reason for these failures was not known. In 1991 members of the Royal Forest and Bird Protection Society commenced breeding North Island Weka Gallirallus australis greyi in captivity for another liberation. Between 1992 and 1996 101 weka were released. We used radio telemetry to follow the fates of the first 17 Weka released in the Karangahake Gorge, near Paeroa, North Island, New Zealand to determine possible outcomes of the liberation. Only one of the 17 birds released survived until 242 days post release. Most newly released Weka were killed by predators, mainly dogs. Future Weka and flightless rail introductions should occur only in areas where predators are being removed to allow survival of released birds and production of young to exceed mortality.

A reappraisal of the late Quaternary fossil vertebrates of Pyramid Valley Swamp, North Canterbury, New Zealand

The late Quaternary fossil vertebrate fauna from deposits at Pyramid Valley, North Canterbury, New Zealand is reassessed. The faunal composition as contained in previous lists is updated, and minimum numbers of individuals represented are given. Measures of faunal diversity are presented and compared with values for present New Zealand systems and other fossil sites. The revised faunal list includes a tuatara, one gecko, at least 46 species of bird, and one species of bat. The avifauna was dominated by moas and waterfowl. The fossil record was biased towards large taxa because of the taphonomic properties of the site. Deposition was slow: individuals were added a few per year and not as a result of catastrophes. Bird diversity, by various measures, was high for a New Zealand site. Diversity indices and rarefraction curves suggest that a site, or group of comparable smaller sites, must contain more than 300 individuals before adequate estimates of the species richness of the sampled fauna are possible. Ten diurnal vertebrate guilds are recognised, several of which are now extinct; all guilds have lost at least 50% of their former constituent species. Sample sizes of two moa taxa were sufficient to allow preliminary analysis of age and sex ratios: in Dinornis giganteus the sex ratio was skewed strongly in favour of the putative female individuals; in Emeus crassus the ratio was nearly equal. Consequences of the differences are discussed. Evidence is presented that Gallirallus minor, reported from fossil deposits, was based on individuals of Gallirallus australis at the lower end of the size range. Evidence of predation of adult moas by Haast's eagle is recorded, and the predator‐prey ratio for a system based on birds is given. The chronology, environment, and components of the fauna are discussed.

Quaternary fossil faunas from caves on Mt Cookson, North Canterbury, South Island, New Zealand

The late Quaternary fossil vertebrate faunas from caves and cliff sites in the limestone of Mt Cookson, near Waiau in North Canterbury, are described. These faunas allow documentation of faunal changes in the area, over the last 40,000 years, and reveal differences from other previously studied areas that are related to climate. Pitfall faunas from the numerous potholes dominate the deposits, but three predator‐accumulated deposits, attributed to the New Zealand falcon Falco novaeseelandiae, were found. The deposits in Merino Cave and Holocene Hole were studied in detail. Merino Cave had two distinct fossil faunas, from which six radiocarbon dates were obtained, showing that deposition spanned the Otiran Glacial period, between 38,000 yrs BP and 14,000 yrs BP. The older of the two Merino Cave faunas, dated at about 38,000 yrs BP, is the first extensive assemblage for the mid‐Otiran period from New Zealand. The moa fauna was dominated by the heavy‐footed moa Pachyornis elephantopus, but the stout‐legged moa Euryapteryx geranoides, upland moa Megalapteryx didinus, large bush moa Dinornis novaezealandiae, and slender moa D. struthoides were present. Carinates included the following: Eyles's harrier Circus eylesi, adzebill Aptornis defossor, large kiwis Apteryx australis or A. haastii, weka Gallirallus australis, New Zealand quail Coturnix novaezelandiae, Finsch's duck Euryanas finschi, kea Nestor notabilis, laughing owl Sceloglaux albifacies, and owlet‐nightjar Aegotheles novaezealandiae. This assemblage indicates an open shrubland ‐grassland environment. The younger Merino Cave fauna was deposited between 20,000 and 14,000 years ago, during the last major glacial advance at the coldest time of the Otira Glaciation. Only moa bones were present, and P. elephantopus again dominated the fauna. This late Otiran population comprised larger individuals than did the mid‐Otiran population, indicating mean size of individuals got bigger as the climate cooled. Holocene Hole had a rich deposit of small birds dating from the late Holocene, between 3,000 and 2,400 yrs BP. This fauna was deposited when continuous beech forest clothed the landscape. By then the large emeids P. elephantopus, E. geranoides, and M. didinus had been replaced in the fauna by the little bush moa Anomalopteryx didiformis in association with the large bush moa D. novaezealandiae. New Zealand quail and pipits Anthus novaeseelandiae were absent from the local fauna which was dominated by a range of forest species. However, the presence ofadzebills and Finsch's ducks, both absent in Holocene forests farther west, reflects the low rainfall and seasonal dryness of the area. Several species of petrels were present on Mt Cookson: Mottled petrels Pterodroma inexpectata. Cook's petrel Pterodroma cookii, shearwaters Puffinus sp., and diving petrels Pelecanoides urinatrix. The falcon deposits were dominated by bones of kiore Rattus exulans, and included a few bones of species introduced to New Zealand by Europeans, indicating that most of the remains were deposited in the last 800 years, or during the post‐human contact period. However, bones of a wide range of bird species, numerically dominated by parakeets Cyanoramphus sp., were also present. Quail and pipit were common, and ternbirds Bowdhria punctala were present, indicating the re‐establishment of shrublands or grasslands in the area during the post-human period. A small amount of material was older, as indicated by preservation characteristics and a single date of about 2,000 yrs BP. This older material contained the following species not present in material of postrat age: wrens Xenicus sp., snipe Coenocorypha cf. aucklandica, short-tailed bats Mystacina sp., Duvaucel's gecko Hoplodactylus duvaucelii, and tuatara Sphenodon sp. These taxa are now extinct or confined to rat-free islands, so these fossil records support the contention that kiore were responsible for the reduction in their mainland ranges.

Relationship between invertebrates eaten by little spotted kiwi,Apteryx owenii, and their availability on Kapiti Island, New Zealand

Abstract Invertebrates available to and those eaten by little spotted kiwi (Apteryx owenii) were studied in young and old forest on Kapiti Island from January 1984 to February 1985. Invertebrate availability was estimated by soil sampling, litter sampling, and pitfall trapping. Items eaten by kiwi were determined by faecal analysis and their contribution to the diet was assessed by numbers of individuals and biomass. Significantly more invertebrate food was available and arthropods eaten in the younger forest type. Little spotted kiwi are selective feeders, choosing large (body length ≥8 mm) slow-moving invertebrates from the upper layers of soil. Scarabaeid beetles and their larvae were the most commonly eaten arthropods. Little spotted kiwi feeding behaviour and diet was compared with that of weka (Gallirallus australis) on Kapiti Island; only minimal overlap was identified.

Macquarie Island flora and fauna management interpreting progress and predictions for the future

The flora and fauna of Macquarie Island, in the subantarctic, have been experiencing a gradual but sure deterioration since the introduction of alien species. The greatest single achievement in attempts to stop this has been success with controlling the European rabbit (Oryctolagus cuniculus). The actual impact of rabbit control on other introduced species causing ecological damage has far exceeded expectations. Plant communities diminished by 100 years of rabbit grazing are re-establishing rapidly. Because of the success with controlling rahbit numbers, total elimination of feral cats (Felis catus) and wekas (Gallirallus australis) can be achieved, with the major potential benefit being the recovery of some seabird populations which are all but extinct on the main island. However, unless the effort given to these and other management problems discussed can be maintained until completion, the progress made will be rapidly lost and greater ecological problems could result.

The wing musculature of the Weka (Gallirallus australis), a flightless rail endemic to New Zealand

The pectoral musculature of the Weka, a flightless New Zealand rail, is almost identical with that of a volant relative, the American coot, even to details of the propatagial complex. Similar observations have been made for other flightless carinates, including ducks and cormorants (Lowe 1928a, 1934, 1935). Ratites, in contrast, have far fewer wing muscles than carinates, and lack a propatagium (Lowe, 1928b; McGowan, 1982). The fact that the loss of flight in carinates is accompanied by such little change in the pectoral musculature, while that of ratites is so radically different, weakens the hypothesis that ratites evolved from carinates through the loss of flight.An assessment of the relationship between muscles and their bony attachment areas shows how little myological information can be deduced from the surface features of bones. Thus, not even the vaguest of muscle reconstructions could have been attempted by studying the pectoral skeleton of the Weka, and similar findings have been made elsewhere (McGowan, 1979, 1982). This raises serious doubts on the validity of reconstructing the musculature of extinct vertebrates, a matter of much interest to palaeontologists.