Secondary poisoning of mammalian predators during possum and rodent control operations at Trounson Kauri Park, Northland, New Zealand

A poison baiting operation at Trounson Kauri Park in Northland, New Zealand using first 1080 and then brodifacoum targeted possums (Trichosurus vulpecula) and rodents (Rattus rattus, Rattus norvegicus and Mus musculus). Predatory mammals were monitored by radio telemetry during the operation. All six feral cats (Felis catus), the single stoat (Mustela erminea) and the single ferret (Mustela furo) being monitored at the beginning of the operation died of secondary poisoning following the 1080 operation. A further two cats and four stoats were monitored through the ongoing poisoning campaign using brodifacoum in a continuous baiting regime. None of these radio tagged carnivores died of secondary poisoning. However, tissue analysis of additional carnivores trapped at Trounson found that cats, weasels (Mustela nivalis) and, to a lesser extent, stoats did contain brodifacoum residues. The duration that the radio-tagged predators were alive in and around Trounson Kauri Park suggests that the secondary poisoning effect was much reduced under the continuous baiting strategy compared to the initial 1080 poison operation.     

Survival of brown kiwi (

Brown kiwi (Apteryx mantelli) in central Northland have been monitored for up to 32 months of sustained exposure to brodifacoum poison. The cereal baits were placed in bait stations to target brushtail possums (Trichosurus vulpecula). Annual survival of 55 radio-tagged adult kiwi in two poisoned forest patches has been high (95.9%), and similar to that in two nearby unpoisoned forest patches and in the patches before poison was used (95.3%). The two adult birds tested of the four that died in the poisoned areas had no traces of brodifacoum at the detection limit of 0.05 mg kg(-1). With an improved detection limit of 0.02 mg kg(-1), no traces of brodifacoum were found in nine eggs collected over 18 months after adults were first exposed to the poison. Of four chicks tested (detection limit: 0.005 to 0.02 mg kg(-1)), that had apparently died of natural causes or were killed by predators, three contained traces of brodifacoum (0.01—0.18 mg kg(-1)). The median survival of 39 radio-tagged chicks in the poisoned areas (36 days) was significantly better than that of 18 chicks in untreated areas nearby (15 days). Kiwi chicks may be more vulnerable than adult kiwi to accidental poisoning because of physiological or behavioural differences; however, the effects of sustained exposure to low levels of brodifacoum poison may not be visible in the adult population for several years. At this stage of the ongoing study, the benefits to kiwi of this method of pest control outweigh the costs, because chick survival is greatly improved.     

Identification of weta foraging on brodifacoum bait and the risk of secondary poisoning for birds on Quail Island, Canterbury, New Zealand

Brodifacoum is a second-generation anticoagulant used for rodent control in New Zealand. Concerns about the poisoning of non-target species have resulted in restrictions being imposed on the mainland. It is, however, still commonly employed on offshore islands. Previous research investigating the poisoning risks of brodifacoum has generally focused on birds eating brodifacoum bait (primary poisoning) or through depredation of live rodents or carrion containing brodifacoum residues (secondary poisoning). Other research has highlighted the potential for secondary poisoning of birds via the consumption of contaminated invertebrates. An inspection of rodent bait stations undertaken on Quail Island revealed that both cave and ground weta were feeding on brodifacoum bait. A sample of ground weta (Hemiandrus n. sp.) and cave weta (Pleioplectron simplex) was removed from Quail Island and exposed to toxic bait for 60 days. These weta were then assayed for brodifacoum residues and the values used to quantify the secondary poisoning risk for bird species found around Quail Island. We also calculated the risk to birds of secondary poisoning from the tree weta (Hemideina ricta) and the risk of primary poisoning via direct consumption of brodifacoum bait. The LD50 estimates indicated a low risk of secondary poisoning from contaminated ground weta and cave weta. By contrast, the estimates indicated a higher risk from larger-bodied tree weta; however, our calculations were based on a single residue concentration value and should be treated with caution. Of most concern was the primary poisoning risk from the brodifacoum bait. The results indicated that all the 17 bird species assessed are more susceptible to primary poisoning than secondary poisoning and access to brodifacoum bait by non-target bird species needs to be minimised.     

Secondary poisoning of mustelids in a New Zealand Nothofagus forest

Eleven radio-tagged stoats ( Mustela erminea ) and one weasel ( M. nivalis ) died of secondary poisoning following Talon 20 P^TM (20 ppm brodifacoum) poisoning operations which killed mice ( Mus musculus ), ship rats ( Rattus rattus ) and probably brushtail possums ( Trichosurus vulpecula ) in a New Zealand beech ( Nothofagus ) forest. This poisoning method could be an especially useful way of restoring New Zealand native bird populations because it kills several predator species in one operation. Potential unwanted side-effects must be researched before its routine use. This research also demonstrates the potential hazards of second-generation anticoagulant rodenticides to conservation of rodent predators in Europe.     

Life history traits contribute to decline of critically endangered lizards at Macraes Flat, Otago

To measure the costs and benefits of an aerial 1080 possum control operation to kereru and kaka in Whirinaki Forest Park, individuals of both species were radio-tagged from October 1998 to June 2002. We monitored birds in one treatment and one non-treatment study area to compare toxin-related mortality, nesting success and survival. The poison operation involved the spreading of non-toxic carrot baits on 1 May 2000, and the toxic baits on 17/18 May 2000. Possums and rats were moderately abundant in both study areas prior to the poison operation, but afterwards few possums and rats remained in the treatment area. All radio-tagged kaka and kereru in the treatment area survived the poison operation. No radio-tagged kereru and too few radio-tagged kaka bred in either study area during the 2000/01 nesting season to show whether reduced possum and rat populations would enable the birds to nest more successfully. A reduction in possum and rat densities in the non-treatment area (and an increase in densities in the treatment area) during 2001/02 meant that during the second nesting season after the poison operation, possum and rat densities were similar in the two study areas. The nesting effort and success of kaka and kereru is described for each of four nesting seasons, with the main cause of nesting failure for both species being predation. While no radio-tagged adult male kaka died during the study, 6 females did, giving them a mean life expectancy of 9.5 years. In contrast, radio-tagged adult kereru suffered high mortality, resulting in a mean life expectancy of just 1.5 years. Predation by introduced mammalian predators was the main cause of mortality of kaka eggs, chicks, fledglings and adult females, and of kereru eggs, chicks, fledglings and adults. Effective control of introduced mammalian predators, including control by aerial 1080 operations, just before mast fruiting events that invariably promote prolific kaka and kereru breeding, should benefit these bird populations.     

Controlling small mammal predators using sodium monofluoroacetate (1080) in bait stations along forestry roads in a New Zealand beech forest

A single five night pulse of sodium monofluroacetate (0.15% 1080) applied in bait stations at two different spacing intervals, 100 and 200 m, along forestry roads in New Zealand beech forest, killed all four of the resident radio-tagged stoats (Mustela erminea) and all three of the resident radio- tagged wild house cats (Felis catus) by secondary poisoning. Gut contents of predators indicated that house mice (Mus musculus), ship rats (Rattus rattus) and bushtail possums (Trichosurus vulpecula) were important sources of the toxin. High kills of predators, possums and rats at both 100 and 200 m spacing regimes suggest that greater efficacy of controlling these pests would be achieved with the latter method. Evidence suggests that routine management of possums and rats using 1080 and brodifacoum has resulted in widespread control of small mammalian carnivores by secondary poisoning in New Zealand forests. However, aerial application of poison can kill large numbers of tomtits (Petroica macrocephala) and robins (Petroica australis) and few other native bird species have been adequately monitored through such operations. Reducing risks to native wildlife is responsible ecological management. Use of bait stations along forestry roads or tracks may be fundamental in mounting cost-effective :Large-scale ground-based protection of native wildlife through safer predator controls.     

Estimating impacts of poison operations using mark-recapture analysis: hihi (

Hihi (Notiomystis cincta) were reintroduced to Mokoia Island, Lake Rotorua, New Zealand, in September 1994, and two years later there was an aerial drop of brodifacoum cereal pellets aimed to eradicate mice (Mus musculus). Using Program MARK, we analyzed data from resighting surveys to assess whether hihi had lower than normal survival in the 6-week interval following the drop. The resighting data were collected on a regular basis over a 3-year period, from 1994-97, allowing us to control for yearly and seasonal variation in resighting and survival probabilities. We initially established that the Cormack-Jolly- Seber model had a good fit to the data and could therefore be used as the global model for our analysis. We then compared a range of simpler candidate models, some of which included a poison effect (an unusual survival rate for the interval after the poison drop). Under the best model (that with the lowest AIC), the survival probability was constant over time and there was no poison effect. The estimated survival probability for the 6 weeks after the poison drop was 0.95, which is slightly higher than the value of 0.89 expected based on pre- and post- poison intervals. The approximate 95% confidence interval for the probability of a bird dying due to poison ranged from -0.17 (i.e., a decrease in mortality rate due to the poison) to +0.04. We therefore concluded that the poison caused at most a negligible increase in mortality, and that mark-recapture analysis on resighting data provided a powerful method for assessing the impact of the poison drop. We discuss the relative costs and benefits of radio tagging versus resighting surveys of banded birds for estimating impacts of poison operations. For species with relatively high resighting rates, such as hihi, analysis of resighting surveys is a much more reliable and cost-efficient methodology.     

Importance of ground weta (

Aerial poisoning using Talon(R) 7-20 baits (active ingredient 20 ppm brodifacoum) was carried out on Motuihe Island, Hauraki Gulf, during the winter of 1997. The operation aimed to eradicate Norway rats (Rattus norvegicus) and house mice (iMus musculus) and to reduce rabbit (Oryctolagus cuniculus) numbers significantly. We studied the diet of feral house cats (Felis earns) before the operation, then monitored the impact of the operation on them to determine whether secondary brodifacoum poisoning caused a reduction in their numbers. Large numbers of rabbits remained after poisoning; this and other observations suggested that insufficient bait had been applied to achieve the aims of the programme. Cat mortality, based on radio- collared animals, was 3/14 (21%). Cats on Motuihe Island appeared to eat rabbit muscle tissue in preference to internal organs; brodifacoum concentrations are lower in muscle than in liver and we suggest that rabbits may be a poorer vector than rodents for secondary poisoning of cats. We also confirmed the risk of an aerial brodifacoum application to a range of non- target bird species. Mortality of pukeko (Porphyrio p. melanotus) and paradise shelducks (Tadorna variegata) was 49% and 60%, respectively. No mortality of New Zealand dotterels (Charadrius obscurus) or variable oystercatchers (Haematopus unicolor) was detected. Twenty-nine individuals of 10 bird species (five indigenous and five introduced) were found dead after the operation and livers of all of them contained residues of brodifacoum; toxin levels averaged 0.84 mu g per g (range 0.12-2.31 mu g per g).     

Brodifacoum residue analysis in water, soil, invertebrates, and birds after rat eradication on Lady Alice Island

Rats were eradicated from Lady Alice Island (Northland, New Zealand) in October 1994, using aerially applied cereal-based bait containing brodifacoum. To determine the fate and non- target impact of brodifacoum, streams, soil, invertebrates, and birds were monitored for 7 months after the baits were applied. No brodifacoum was detected in any of the stream or soil samples. Brodifacoum was detected in cave weta found on baits, and in morepork and red-crowned parakeet liver tissue. Significant contamination of water and soil is unlikely after a single aerial application of brodifacoum baits. Invertebrates such as cave weta may be at risk of consuming brodifacoum bait, morepork and red-crowned parakeet may be at risk of secondary poisoning.     

Estimating impacts of poison operations using mark-recapture analysis and population viability analysis: an example with New Zealand robins (

Several recent studies have used "roll calls"—searches for individually-marked birds—to assess impacts of aerial poison operations on non-target species. Roll calls have advantages over methods such as 5-minute bird counts, call counts, and dead body counts, but roll calls are based on the assumption that detection rates are 100%, or that detection rates are constant over time and space. They also require more than one group of birds, at a poisoned and unpoisoned site for example, for valid statistical comparisons. With minor adjustment of field methods, however, a series of surveys can be treated as a mark-recapture experiment, allowing powerful analysis without such restrictive assumptions. Survival and detection rates can be estimated independently for each time interval, and alternative models fitted to the data for factors affecting those rates. Using the software package MARK, we analyzed data for New Zealand robins (Petroica australis) on Tiritiri Matangi Island to estimate impact of an aerial brodifacoum operation conducted in September 1993 to eradicate kiore (Rattus exulans). The population was established by translocations in 1992 and 1993, and consisted of 40 birds at the time of the operation. Taking seasonal and yearly variation in detection and survival rates into account, we estimate that 11% of robins (4-5 birds) died as a result of the poison. There was strong evidence that survival probability was lower immediately after the operation, despite the small number of birds disappearing. The poison effect was confined to the interval from September-October 1993, including the first two weeks after the poison drop, and survival for subsequent monthly intervals was consistent with the normal summer rate. Using simulation modelling based on our data from the population, we predict that the operation set population growth back by about one year but had no longer-term impact.     

Forest bird mortality and baiting practices in New?Zealand aerial 1080 operations from 1986 to 2009

We collated 48 surveys of individually banded birds or birds fitted with radio transmitters that were checked before and after 1080 poison (sodium fluoroacetate) baits were aerially distributed to control brushtail possums (Trichosurus vulpecula) in New?Zealand forests. The surveys were associated with 34 pest control operations from 1986 to 2009 and covered 13 native bird species, of which four were kiwi (Apteryx spp.). Sample sizes ranged from 1 to 46 birds (median 15). In 12 cases a sample of 1 to 42 birds (median 13) was surveyed in an untreated area at the same time. In total, 748 birds were checked before and after operations and 48 birds disappeared or were found dead. In non-treatment areas, 193 birds were checked and four died. Surveys of kiwi, whio (Hymenolaimus malacorhynchos), kaka (Nestor meridionalis) and kokako (Callaeas cinerea) were grouped for meta-analyses. The 95% pooled upper confidence bounds for the point estimate of zero mortality were each less than 4% for kiwi, kaka and kokako indicating only a small risk of mortality during 1080 pest control operations. Prefeeding with non-toxic baits increased from 22% (1998?1999) to 79% (2007?2008) in 322 operations on public conservation lands but was used in only 9 (26%) of the operations during which individually marked birds were monitored. We caution that failure to observe bird deaths in small samples may lead to weak inference about zero mortality across a population, most surveys in the review did not involve prefeeding, and that 11 native bird species for which deaths were reported after 1080 operations have not been studied.     

Mortality of North Island tomtits (

Aerial poisoning operations with carrot or cereal baits are used to control brushtail possum (Trichosurus vulpecula) populations in New Zealand forests for ecosystem conservation and to stop the spread of bovine tuberculosis to cattle and deer herds on adjacent farmland. Although various measures have been implemented to reduce the incidence of bird kills, dead birds continue to be found after poison operations. Colour- banded North Island tomtits (Petroica macrocephala toitoi) were monitored in treatment and non-treatment areas in Pureora Forest Park to determine the costs and benefits of aerial 1080 possum poisoning operations to tomtit populations. The August 1997 operation (carrot baits with very little chaff, 0.08 % w/w 1080, 10 kg ha(-1)), resulted in 11 (79%) of 14 tomtits disappearing, but none of nine from the non-treatment area. Whether the birds died of primary or secondary poisoning is unknown. No tomtits in either treatment or non-treatment areas disappeared following the August 1998 operation (cereal baits, 0.08% w/w 1080, 5 kg ha(-1)). The carrot bait operation resulted in almost all possums and rodents being killed, but a few possums and rodents survived the cereal bait operation, apparently because of a gap in bait distribution. During the 1997/98 nesting season, tomtit pairs in the 1997 treatment area had high nesting success (80% of nests fledged chicks, mean of four fledglings per nest). Even so, by the following spring it seemed that the population had not recovered to its pre-poison level. Further research on this topic is warranted, the priority being to monitor tomtit mortality during more aerial 1080-cereal bait operations in order to assess the likely risks of using those baits.     

Large-Scale Poisoning of Ship Rats (

This paper describes the impact of nine poison operations on ship rats in four areas (35 ha to 3200 ha) of North Island forest. Poisoning with 1080, brodifacoum, or pindone killed 87- 100% of rats, based on trapping and tracking-tunnel indices. Rat populations took 4-5 months to recover. Operations to protect nesting birds should therefore coincide with the onset of nesting and be rePeated each year, although not necessarily with the same methods. Population reduction declined each year at Mapara, King Country, during three annual 1080 operations which used the same lures and baits, but remained high at Kaharoa, Bay of Plenty, where poison toxicity was higher, non- toxic bait was pre-fed, and poisoning methods varied each year. Mouse tracking rates increased in poisoned forests 3-6 months after poisoning if the initial kill of rats exceeded 90%, Peaked 7-9 months after poisoning, then declined to pre-poison levels. Future research should focus on how prey and non-prey species within a forest community respond to a temporary reduction in rat numbers, and on methods to maintain low rat densities after initial knock-down.     

Capture myopathy in little bustards after trapping and marking

Four little bustards (Tetrax tetrax) (one adult and three juvenile males), captured with leg nooses and fitted with a backpack radiotag, died after capture. The first bird was found after 16 days with its left foot caught in the harness and died after 1 day. The other birds showed symptoms of capture myopathy after release, such as the difficulty or inability to fly and/or walk. They died after 5, 6, and 8 days, respectively. At necropsy, muscles affected in all cases were those from the legs, and these were diffusely pale and dull, with a soft friable texture. Microscopically these muscles had multiple foci of myofiber fragmentation, loss of striation, and necrosis; a mononuclear cell infiltrate was observed in muscle from two birds. These findings suggest the little bustard is susceptible to capture myopathy and that caution should be exercised during its capture and handling.     

Impacts of Aerial 1080 Poisoning on the Birds of Rangitoto Island, Hauraki Gulf, New Zealand

Bird populations were monitored for one year (October 1990- October 1991) to determine whether the 1080 poison used to eradicate possums and wallabies on Rangitoto Island had had any detrimental effects on them. There was no significant decline in bird numbers recorded immediately after poisoning, with four species increasing in abundance (P <0.001). Twelve months after the operation the abundance of four species had increased significantly (P <0.001). The poisoning does not appear to have had any negative effect on the bird populations of Rangitoto, while the removal of browsing mammals may in future prove to have beneficial effects.     

Brodifacoum residues in possums (

The presence of brodifacoum residues in possum (Trichosurus vulpecula) livers following routine possum control was investigated. Possums were poisoned in six nature reserves in the Wellington Region, New Zealand, using cereal baits containing 20 mg kg(-1) brodifacoum dispensed from bait stations. Thirty-five surviving possums, and five dead possums were sampled from the reserves following poisoning, and their livers analysed for the presence of brodifacoum. The majority (83%) of samples contained brodifacoum at concentrations ranging from 0.007 mg kg(-1) to 6.2 mg kg(-1). The presence of significant quantities of brodifacoum in possum carcasses following poisoning operations creates potential for secondary and tertiary poisoning of non-target species.     

Secondary poisoning of stoats after an aerial 1080 poison operation in Pureora Forest, New Zealand

Stoats were monitored by three methods through an aerial 1080 poisoning operation at Waimanoa, Pureora Forest in August 1997. Tracking rates and number of live captures were used as indices of abundance, and radio-transmitters were used to follow individual animals. All 13 stoats with radio-transmitters within the poisoned area died between 2-18 days after the operation. No mustelids were tracked or live-trapped after the operation for three months. Of the radio-tracked stoats that died, rat remains occurred in 67%, passerine birds in 17%, cave weta in 17% and possum in 8%. Residues of 1080 were found in 12 of the 13 dead stoats. Our findings have important implications for the management of threatened species. Stoats are known to be a major factor in the continuing decline of some native birds. Previously, the potential of secondary poisoning to control stoats land other predators) in New Zealand had focused on the use of anticoagulants, as these compounds persist and can accumulate in predators over a longer period. However, our results suggest that secondary poisoning with an acute toxin can also be highly efficient. This may also have greater public acceptability.     

The risks, costs and benefits of using brodifacoum to eradicate rats from Kapiti Island, New Zealand

In 1996 an eradication operation against two species of rats (Rattus norvegicus and R. exulans was conducted on Kapiti Island (1965 ha) and its small offshore islands. Trials with non-toxic baits had been carried out to help determine the risks to non-target species, and research was undertaken to collect baseline data for measuring the response of vegetation, invertebrates, reptiles and birds to the removal of rats. Talon 7-20 bait (containing 0.002% brodifacoum) was distributed over Kapiti Island in September and October by helicopter and by hand, while bait stations were used on the offshore islands. Impacts on birds and reef fish were investigated. Although there were non-target bird deaths as a result of the poisoning operation, post-eradication monitoring indicated that the toxin had no deleterious effect on breeding and most losses would be rapidly made up by recruitment of new individuals into the breeding population. There was no evidence that reef fish were negatively affected. The successful removal of rats has apparently resulted in a significantly improved survival rate for stitchbirds (Notiomystis cincta) and saddlebacks (Philesturnus carunculatus). Benefits to other taxa are expected and will be documented as follow-up studies are completed.     

西藏"一江两河"流域鸟类资源调查初报

自2006年以来对西藏"一江两河"流域的鸟类资源进行了观测与考察,共记录鸟类15目37科125种,约占全国鸟类的9.4%.该区域鸟类以古北界成分为主,达78种,占总数的62.4%,此外还有东洋界鸟类22种,广布种25种.鸟类中多为留鸟,种类达84种,占到总数的67.2%,冬候鸟29种,夏候鸟12种.该区域有多种被保护的鸟类资源,其中IUCN收录6种,CITES收录19种,中国濒危物种红皮书收录13种;中国重点保护动物名录收录20种.     

Lead poisoning and heavy metal exposure of golden eagles ( Aquila chrysaetos ) from the European Alps

Lead poisoning and organ levels of the non-essential heavy metals lead, cadmium and mercury of seven free-ranging golden eagles (Aquila chrysaetos) from the European Alps, and of one 23-year-old captive golden eagle are reported. All birds were found dead or moribund during the years 2000 and 2001 in Austria, Germany and Switzerland. One golden eagle from Switzerland with extraordinarily high lead residues in its liver and kidney was clearly identified as lethally lead poisoned. Another bird from the same region was found still alive and died in a wildlife rehabilitation center, showing lead residues in its organs known for acute lead poisoning with detrimental physiological effects, such as nervous disorders and the inhibition of the hemoglobine synthesis. Concentrations of cadmium, mercury and lead residues in the organs of the other five free-ranging birds, and in the long-lived captive golden eagle, were low and represent the natural background levels in birds of prey of the terrestrial food web. This is the first published report of lead poisoning in golden eagles from Switzerland. Sources for lead poisoning in golden eagles in the Alpine region are discussed.