Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3498
James I. Livingstone, S. Horn, K. Broome, R. Sagar
: House mice ( Mus musculus ) are highly invasive mammals and can cause extensive ecosystem damage on islands where they are the sole mammalian pest species. Capability to eradicate mice has improved in recent years. Mouse eradication has been achieved on large islands where mice cohabit with other rodents and islands where mice are the sole mammalian pest. As the islands targeted for eradication become larger and more challenging, reduced toxic cereal bait application rates can reduce both complexity and cost, and ultimately make currently unachievable operations feasible. Auckland Island (45 891 ha) in New Zealand’s subantarctic region is a desirable target for mouse eradication. However, logistics at this scale indicate that the required bait volume using New Zealand’s currently agreed best practice (two applications, each 8 kg ha −1 ) is not feasible using available resources. Small islands provide an opportunity to experiment with eradication methods with acceptable levels of risk. Here we test the eradication of mice from a small island in New Zealand using a low bait application rate. A single application of 3 kg ha −1 of rodent cereal baits containing brodifacoum was aerially applied on Motuareronui/Adele Island (87 ha) in New Zealand’s Abel Tasman National Park, in winter 2017. Intensive monitoring immediately following bait application showed the mouse population rapidly succumbed to the baiting operation. Rodent dog checks 5 months after baiting increased confidence in the operations’ success. A mouse was detected and caught 7 months later in a biosecurity trap network, but genetic analysis determined that this mouse was a recent incursion rather than the result of eradication failure. No further mice were caught, and the eradication was declared a success two summers after baiting. This study shows how undertaking, reporting on, and reviewing appropriate high-standard field trials can contribute to the evolution of best practice. This study adds to a growing body of evidence that low application baiting (relative to best practice) can be considered feasible for mouse eradications on islands where the benefits outweigh the risks, and points to further avenues of research to reduce risk and broaden the application of this method.
{"title":"How low can you sow? House mouse eradication on Motuareronui/Adele Island","authors":"James I. Livingstone, S. Horn, K. Broome, R. Sagar","doi":"10.20417/nzjecol.47.3498","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3498","url":null,"abstract":": House mice ( Mus musculus ) are highly invasive mammals and can cause extensive ecosystem damage on islands where they are the sole mammalian pest species. Capability to eradicate mice has improved in recent years. Mouse eradication has been achieved on large islands where mice cohabit with other rodents and islands where mice are the sole mammalian pest. As the islands targeted for eradication become larger and more challenging, reduced toxic cereal bait application rates can reduce both complexity and cost, and ultimately make currently unachievable operations feasible. Auckland Island (45 891 ha) in New Zealand’s subantarctic region is a desirable target for mouse eradication. However, logistics at this scale indicate that the required bait volume using New Zealand’s currently agreed best practice (two applications, each 8 kg ha −1 ) is not feasible using available resources. Small islands provide an opportunity to experiment with eradication methods with acceptable levels of risk. Here we test the eradication of mice from a small island in New Zealand using a low bait application rate. A single application of 3 kg ha −1 of rodent cereal baits containing brodifacoum was aerially applied on Motuareronui/Adele Island (87 ha) in New Zealand’s Abel Tasman National Park, in winter 2017. Intensive monitoring immediately following bait application showed the mouse population rapidly succumbed to the baiting operation. Rodent dog checks 5 months after baiting increased confidence in the operations’ success. A mouse was detected and caught 7 months later in a biosecurity trap network, but genetic analysis determined that this mouse was a recent incursion rather than the result of eradication failure. No further mice were caught, and the eradication was declared a success two summers after baiting. This study shows how undertaking, reporting on, and reviewing appropriate high-standard field trials can contribute to the evolution of best practice. This study adds to a growing body of evidence that low application baiting (relative to best practice) can be considered feasible for mouse eradications on islands where the benefits outweigh the risks, and points to further avenues of research to reduce risk and broaden the application of this method.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41409568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3499
Emmanuel Oyston, S. Horn, E. Murphy
: The house mouse ( Mus musculus ) is considered the most difficult rodent species to eradicate from islands. Eradication projects require careful planning and execution of an ‘over-engineering’ approach to ensure every individual of the targeted population is encountered and removed. Aerial broadcasting of rodenticides has been the method of choice for island rodent eradications since the 1990s and the methods and parameters continue to be refined. Mice were recently eradicated from Te Pākeka/Maud Island (318 ha) in winter 2019 using an aerial baiting prescription that was 50% less than the current best-practice baiting prescription. Using a rapid eradication assessment, it was proven that a combination of static and mobile surveillance devices could provide a high level of confidence of eradication success early on (4 months post-bait application). This paper describes the context, methodology, and outcomes of this low-sow rate trial in order to inform future projects. DNA profiling from the most recent mouse population established on Te Pākeka/Maud Island identifies the challenges of maintaining island biosecurity with the current available tools and in a context of increasing invasion pathways. The ability to adopt lower sowing rates for island mouse eradications reduces both financial and logistical barriers thereby allowing wildlife managers to implement mouse eradications on the world’s most remote islands.
{"title":"A trial on Te Pākeka/Maud Island for reducing aerial baiting sow-rates for the eradication of house mice","authors":"Emmanuel Oyston, S. Horn, E. Murphy","doi":"10.20417/nzjecol.47.3499","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3499","url":null,"abstract":": The house mouse ( Mus musculus ) is considered the most difficult rodent species to eradicate from islands. Eradication projects require careful planning and execution of an ‘over-engineering’ approach to ensure every individual of the targeted population is encountered and removed. Aerial broadcasting of rodenticides has been the method of choice for island rodent eradications since the 1990s and the methods and parameters continue to be refined. Mice were recently eradicated from Te Pākeka/Maud Island (318 ha) in winter 2019 using an aerial baiting prescription that was 50% less than the current best-practice baiting prescription. Using a rapid eradication assessment, it was proven that a combination of static and mobile surveillance devices could provide a high level of confidence of eradication success early on (4 months post-bait application). This paper describes the context, methodology, and outcomes of this low-sow rate trial in order to inform future projects. DNA profiling from the most recent mouse population established on Te Pākeka/Maud Island identifies the challenges of maintaining island biosecurity with the current available tools and in a context of increasing invasion pathways. The ability to adopt lower sowing rates for island mouse eradications reduces both financial and logistical barriers thereby allowing wildlife managers to implement mouse eradications on the world’s most remote islands.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41817625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3486
Derek Brown, K. Broome, Kingsley Timpson
: Feral goats ( Capra aegagrus hircus ) were eradicated from Auckland Island, a National Nature Reserve and World Heritage site, between 1989 and 1991. Goats had established on the main Auckland Island following several releases in the 19th century. The population, amongst the most southerly ever recorded, was restricted to the northernmost areas of the island, with environmental conditions appearing unfavourable for southward spread, and the population stable at c. 100 individuals during scientific studies in the 1970s and 1980s. These studies recommended eradication of the goats because of their damaging effect on indigenous vegetation, especially subantarctic endemic species. The main cull occurred in November 1989 when two full-time and three part-time hunters shot 103 goats over 74 hunter-days effort. At least two more were poisoned using 1080 toxin applied to cut foliage of highly palatable species. A subsequent operation in February 1991 found limited sign, saw no animals, and again used poisoned foliage which possibly accounted for further animals. The last known goat was a solitary male shot from a helicopter in October 1991. Eradication was relatively straightforward, with unfavourable weather and logistical constraints due to the island’s isolation the greatest challenges to success. Scientific monitoring of vegetation recovery has been insufficient but anecdotal observations suggest a dramatic recovery of many flora species. This recovery is tempered by the continuing presence of feral pigs ( Sus scrofa ) in the same location.
{"title":"The eradication of feral goats from Auckland Island","authors":"Derek Brown, K. Broome, Kingsley Timpson","doi":"10.20417/nzjecol.47.3486","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3486","url":null,"abstract":": Feral goats ( Capra aegagrus hircus ) were eradicated from Auckland Island, a National Nature Reserve and World Heritage site, between 1989 and 1991. Goats had established on the main Auckland Island following several releases in the 19th century. The population, amongst the most southerly ever recorded, was restricted to the northernmost areas of the island, with environmental conditions appearing unfavourable for southward spread, and the population stable at c. 100 individuals during scientific studies in the 1970s and 1980s. These studies recommended eradication of the goats because of their damaging effect on indigenous vegetation, especially subantarctic endemic species. The main cull occurred in November 1989 when two full-time and three part-time hunters shot 103 goats over 74 hunter-days effort. At least two more were poisoned using 1080 toxin applied to cut foliage of highly palatable species. A subsequent operation in February 1991 found limited sign, saw no animals, and again used poisoned foliage which possibly accounted for further animals. The last known goat was a solitary male shot from a helicopter in October 1991. Eradication was relatively straightforward, with unfavourable weather and logistical constraints due to the island’s isolation the greatest challenges to success. Scientific monitoring of vegetation recovery has been insufficient but anecdotal observations suggest a dramatic recovery of many flora species. This recovery is tempered by the continuing presence of feral pigs ( Sus scrofa ) in the same location.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42265706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3483
Derek Brown, Finlay Cox, Alex Fergus
: Feral sheep were eradicated from Campbell Island (Motu Ihupuku) – a National Reserve, Nature Reserve and UNESCO World Heritage Site in subantarctic New Zealand – in three distinct stages from 1970 to 1991. The sheep derived from farming attempts on the island, starting in 1895 and abandoned by 1931. The potential genetic and commercial value of the isolated sheep population meant proposed eradication plans were not wholly supported. Compromise solutions were initially implemented that required the construction of two fences, one in 1970 and one in 1984, to separate three geographic portions of the island. This separation was to facilitate staged removal of sheep and vegetation recovery in one portion of the island whilst retaining the sheep in another portion until eradication was fully committed. Sheep were largely removed by small field teams of experienced hunters using standard ground-hunting procedures in three separate operations, with follow-up operations required to remove small numbers of survivors in all three events. Approximately 7000 sheep were shot over the three operations or associated control/eradication efforts. A significant ecological response has been reported, including a recovery in range, abundance, and individual plant size for subantarctic macroforbs ( Anisotome spp., Azorella polaris , and Pleurophyllum spp.), but also for grasses ( Chionochloa antarctica and Poa spp.).
{"title":"The eradication of Campbell Island sheep and subsequent ecological response","authors":"Derek Brown, Finlay Cox, Alex Fergus","doi":"10.20417/nzjecol.47.3483","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3483","url":null,"abstract":": Feral sheep were eradicated from Campbell Island (Motu Ihupuku) – a National Reserve, Nature Reserve and UNESCO World Heritage Site in subantarctic New Zealand – in three distinct stages from 1970 to 1991. The sheep derived from farming attempts on the island, starting in 1895 and abandoned by 1931. The potential genetic and commercial value of the isolated sheep population meant proposed eradication plans were not wholly supported. Compromise solutions were initially implemented that required the construction of two fences, one in 1970 and one in 1984, to separate three geographic portions of the island. This separation was to facilitate staged removal of sheep and vegetation recovery in one portion of the island whilst retaining the sheep in another portion until eradication was fully committed. Sheep were largely removed by small field teams of experienced hunters using standard ground-hunting procedures in three separate operations, with follow-up operations required to remove small numbers of survivors in all three events. Approximately 7000 sheep were shot over the three operations or associated control/eradication efforts. A significant ecological response has been reported, including a recovery in range, abundance, and individual plant size for subantarctic macroforbs ( Anisotome spp., Azorella polaris , and Pleurophyllum spp.), but also for grasses ( Chionochloa antarctica and Poa spp.).","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41695842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3489
Dean Anderson, Celia Latham, P. McClelland, D. Latham
: Feral pigs ( Sus scrofa ) were introduced to Auckland Island in subantarctic New Zealand in 1807. They established and became invasive, subsequently causing substantial unwanted impacts on native biodiversity. Understanding pig movement behaviour and habitat selection can lead to focused, efficient, and effective management efforts, especially during initial knockdown of the population. Here we used location data from ARGOS telemetry collars deployed on 15 Auckland Island pigs from 2007 to 2008 to estimate seasonal home-range sizes and habitat selection. The annual home-range sizes of pigs ranged from 1.26 to 36.4 km 2 , with a mean of 14.1 km 2 (SD = 11.3 km 2 ). The variation in home-range sizes between winter and summer was generally low. We found that the pig population selected areas of their home ranges that were on average closer to the coast (though this was not necessarily selection for beaches or strandlines per se) during the spring and summer months. Pigs also selected areas closer to the coast in winter, albeit with weaker strength of selection than in spring and summer. We had insufficient data to differentiate between different coastal habitats (i.e. cliffs versus beaches and strandlines). We also found that pigs showed annual selection for tussock, hills with north-facing aspects, and rivers and streams. They avoided areas of bog-swamp and forest-scrub. Importantly, we do not know what food resources or other factors were driving habitat selection. Our results highlight areas selected by pigs that could be targeted for initial knockdown; however, staff will have to search all habitats on the island to achieve rapid eradication or a protracted mop-up of survivors. Simply targeting key accessible areas like strandlines and coastal forests will not achieve eradication. Based on these home-range sizes, eradication would require a hunter path spacing of no more than 1.4 km to ensure every pig home range was searched at least once.
野猪(Sus scrofa)于1807年被引入新西兰亚南极的奥克兰岛。它们定居下来并成为入侵物种，随后对本地生物多样性造成了严重的有害影响。了解猪的运动行为和栖息地选择可以导致集中、高效和有效的管理工作，特别是在种群的初始击倒期间。在这里，我们使用了2007年至2008年在15头奥克兰岛猪上部署的ARGOS遥测项圈的位置数据，以估计季节性的家庭范围大小和栖息地选择。猪的年家庭活动范围为1.26 ~ 36.4 km2，平均14.1 km2 (SD = 11.3 km2)。在冬季和夏季之间，家庭范围大小的变化通常很低。我们发现，在春季和夏季，猪群选择了平均更靠近海岸的家园区域(尽管这并不一定是对海滩或海岸线本身的选择)。猪在冬季也会选择靠近海岸的地区，尽管选择的强度比春季和夏季弱。我们没有足够的数据来区分不同的海岸栖息地(即悬崖、海滩和海岸线)。我们还发现，猪对草丛、朝北的山丘、河流和溪流表现出年度选择。他们避开了沼泽和森林灌木丛地区。重要的是，我们不知道是什么食物资源或其他因素推动了栖息地的选择。我们的结果突出了猪选择的可能被初始敲除的区域;然而，工作人员必须搜索岛上的所有栖息地，以实现迅速消灭或长期清除幸存者。仅以海岸线和沿海森林等主要可达地区为目标是无法实现根除的。基于这些家庭范围的大小，根除将需要猎人路径间距不超过1.4公里，以确保每头猪的家庭范围至少被搜索一次。
{"title":"Analysis of spatiotemporal patterns of home range use and habitat selection to inform management of feral pigs on Auckland Island","authors":"Dean Anderson, Celia Latham, P. McClelland, D. Latham","doi":"10.20417/nzjecol.47.3489","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3489","url":null,"abstract":": Feral pigs ( Sus scrofa ) were introduced to Auckland Island in subantarctic New Zealand in 1807. They established and became invasive, subsequently causing substantial unwanted impacts on native biodiversity. Understanding pig movement behaviour and habitat selection can lead to focused, efficient, and effective management efforts, especially during initial knockdown of the population. Here we used location data from ARGOS telemetry collars deployed on 15 Auckland Island pigs from 2007 to 2008 to estimate seasonal home-range sizes and habitat selection. The annual home-range sizes of pigs ranged from 1.26 to 36.4 km 2 , with a mean of 14.1 km 2 (SD = 11.3 km 2 ). The variation in home-range sizes between winter and summer was generally low. We found that the pig population selected areas of their home ranges that were on average closer to the coast (though this was not necessarily selection for beaches or strandlines per se) during the spring and summer months. Pigs also selected areas closer to the coast in winter, albeit with weaker strength of selection than in spring and summer. We had insufficient data to differentiate between different coastal habitats (i.e. cliffs versus beaches and strandlines). We also found that pigs showed annual selection for tussock, hills with north-facing aspects, and rivers and streams. They avoided areas of bog-swamp and forest-scrub. Importantly, we do not know what food resources or other factors were driving habitat selection. Our results highlight areas selected by pigs that could be targeted for initial knockdown; however, staff will have to search all habitats on the island to achieve rapid eradication or a protracted mop-up of survivors. Simply targeting key accessible areas like strandlines and coastal forests will not achieve eradication. Based on these home-range sizes, eradication would require a hunter path spacing of no more than 1.4 km to ensure every pig home range was searched at least once.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44215082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3494
A. Glen, R. Sagar, Talia Brav-Cubitt, Paul Jacques
: In order to conserve important biodiversity values, eradication of feral cats ( Felis catus ) is planned on Auckland Island in the New Zealand subantarctic region. This eradication will require detailed knowledge of the abundance, distribution, movement behaviour and detection probability of cats on the island. We investigated these parameters on a peninsula at the northern end of the island using live trapping, camera trapping, and scat searches with and without detection dogs. Here, we compare the results of these methods, and discuss their utility for the planned eradication. Four cats were captured and fitted with GPS collars. Camera traps with 500 m spacing detected all these individuals on multiple occasions, and at multiple locations. At least 12 other individuals were also captured on camera. Excluding every second camera (to simulate 1000 m spacing) resulted in failure to detect 32% of known individuals. Population density estimates from camera trapping varied from 0.7–1.0 cats km -2 . Humans found 29 cat scats, and dogs found 33. Genetic analysis estimated that these came from a minimum of ten individuals. Camera trapping should be repeated during the operational and confirmation phases of the eradication to monitor spatial and temporal variation in cat density, detect survivors, and help confirm eradication success. Scat collection, with and without dogs, can supplement data from camera trapping. With larger sample sizes of scats, DNA profiling may also allow cat abundance to be estimated.
{"title":"Monitoring and detection of feral cats on Auckland Island","authors":"A. Glen, R. Sagar, Talia Brav-Cubitt, Paul Jacques","doi":"10.20417/nzjecol.47.3494","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3494","url":null,"abstract":": In order to conserve important biodiversity values, eradication of feral cats ( Felis catus ) is planned on Auckland Island in the New Zealand subantarctic region. This eradication will require detailed knowledge of the abundance, distribution, movement behaviour and detection probability of cats on the island. We investigated these parameters on a peninsula at the northern end of the island using live trapping, camera trapping, and scat searches with and without detection dogs. Here, we compare the results of these methods, and discuss their utility for the planned eradication. Four cats were captured and fitted with GPS collars. Camera traps with 500 m spacing detected all these individuals on multiple occasions, and at multiple locations. At least 12 other individuals were also captured on camera. Excluding every second camera (to simulate 1000 m spacing) resulted in failure to detect 32% of known individuals. Population density estimates from camera trapping varied from 0.7–1.0 cats km -2 . Humans found 29 cat scats, and dogs found 33. Genetic analysis estimated that these came from a minimum of ten individuals. Camera trapping should be repeated during the operational and confirmation phases of the eradication to monitor spatial and temporal variation in cat density, detect survivors, and help confirm eradication success. Scat collection, with and without dogs, can supplement data from camera trapping. With larger sample sizes of scats, DNA profiling may also allow cat abundance to be estimated.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42104641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3497
R. Sagar, Finlay Cox, S. Horn, James Russell
: House mice ( Mus musculus ) are an invasive species on Auckland Island in the New Zealand subantarctic and planning for their eradication is underway. Mast seeding events cause rodent populations to irrupt, though little is known about this phenomenon in snow tussock grass ( Chionochloa spp.) systems on Southern Ocean islands. The aim of this study was to understand population fluctuations of mouse abundance on Auckland Island for the 2 years following a mast event, and with which tools to monitor abundance, to inform planning of bait application for eradication. Mouse populations were studied using kill and live trapping at two sites on Auckland Island, and mouse density was estimated using spatially explicit capture-recapture models. Mouse population density was highest during summer mast seeding of Chionochloa antarctica and then declined the following winter and subsequently remained low for the following year. Breeding remained seasonal, with a pulse in early summer and a very low level continuing through winter in both years, regardless of mast conditions. These results are similar to those from other cool temperate Southern Ocean islands where seasonal resource availability appears to drive breeding. Throughout the study the capture probability of mice was generally higher when population density was lower, which highlights that conclusions about population trends could be misleading if abundance indices are not calibrated to measures of population density. Mouse eradication should preferentially take place outside of a mast event but would likely still succeed during and following a mast event. Our work fills a key knowledge gap about rodent population trends during mast events for Southern Ocean islands, which is particularly important where eradications are planned.
{"title":"Population trends of house mice during tussock mast seeding on Auckland Island","authors":"R. Sagar, Finlay Cox, S. Horn, James Russell","doi":"10.20417/nzjecol.47.3497","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3497","url":null,"abstract":": House mice ( Mus musculus ) are an invasive species on Auckland Island in the New Zealand subantarctic and planning for their eradication is underway. Mast seeding events cause rodent populations to irrupt, though little is known about this phenomenon in snow tussock grass ( Chionochloa spp.) systems on Southern Ocean islands. The aim of this study was to understand population fluctuations of mouse abundance on Auckland Island for the 2 years following a mast event, and with which tools to monitor abundance, to inform planning of bait application for eradication. Mouse populations were studied using kill and live trapping at two sites on Auckland Island, and mouse density was estimated using spatially explicit capture-recapture models. Mouse population density was highest during summer mast seeding of Chionochloa antarctica and then declined the following winter and subsequently remained low for the following year. Breeding remained seasonal, with a pulse in early summer and a very low level continuing through winter in both years, regardless of mast conditions. These results are similar to those from other cool temperate Southern Ocean islands where seasonal resource availability appears to drive breeding. Throughout the study the capture probability of mice was generally higher when population density was lower, which highlights that conclusions about population trends could be misleading if abundance indices are not calibrated to measures of population density. Mouse eradication should preferentially take place outside of a mast event but would likely still succeed during and following a mast event. Our work fills a key knowledge gap about rodent population trends during mast events for Southern Ocean islands, which is particularly important where eradications are planned.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45170608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3495
Finlay Cox, Paul Jacques, Micaela Kirby-Crowe, E. Murphy
: Primary poisoning is an important method to ensure the successful eradication of cats ( Felis catus ) from large islands. Poison bait options for feral cat eradications and landscape-scale control in New Zealand are limited at present. As part of the development of a toxic bait for cats that can be aerially distributed, a non-toxic palatability trial was undertaken on Auckland Island to compare three types of prototype meat-based bait and one currently registered fishmeal polymer pellet for their palatability to feral cats and non-target species. Degradation rates of baits over a range of environmental conditions were also estimated by taking photographs of baits at regular intervals and inferring degradation from visual appearance of baits over time. Fourteen individual cats were sighted on 144 occasions with all individuals consuming at least one bait type. Results show that the three prototype meat baits were significantly more palatable than the fishmeal polymer baits. No native non-target animals were observed consuming any of the baits during the trial. Fishmeal polymer baits degraded at a slower rate than the meat-based matrices. Palatability results for the meat-based matrices are encouraging. Further trials of a toxic meat-based bait will be required to assess efficacy in pursuit of a registered product for wider use.
{"title":"Field palatability and degradation of a selection of feral cat bait matrices on Auckland Island","authors":"Finlay Cox, Paul Jacques, Micaela Kirby-Crowe, E. Murphy","doi":"10.20417/nzjecol.47.3495","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3495","url":null,"abstract":": Primary poisoning is an important method to ensure the successful eradication of cats ( Felis catus ) from large islands. Poison bait options for feral cat eradications and landscape-scale control in New Zealand are limited at present. As part of the development of a toxic bait for cats that can be aerially distributed, a non-toxic palatability trial was undertaken on Auckland Island to compare three types of prototype meat-based bait and one currently registered fishmeal polymer pellet for their palatability to feral cats and non-target species. Degradation rates of baits over a range of environmental conditions were also estimated by taking photographs of baits at regular intervals and inferring degradation from visual appearance of baits over time. Fourteen individual cats were sighted on 144 occasions with all individuals consuming at least one bait type. Results show that the three prototype meat baits were significantly more palatable than the fishmeal polymer baits. No native non-target animals were observed consuming any of the baits during the trial. Fishmeal polymer baits degraded at a slower rate than the meat-based matrices. Palatability results for the meat-based matrices are encouraging. Further trials of a toxic meat-based bait will be required to assess efficacy in pursuit of a registered product for wider use.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45215837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3490
Finlay Cox, S. Horn, W. Bannister, Norma. MacDonald
: Since their liberation in 1807, feral pigs ( Sus scrofa ) have negatively impacted ecosystem health and processes on subantarctic Auckland Island, New Zealand. Eradication of invasive alien species is often critical to restoration programmes and preventing species extinctions. Eradication programmes utilising multiple techniques have allowed feral pig eradications on large islands. Protracted eradication programmes can have a higher risk of failure due to factors such as biological, logistical, social, and funding support. A temporary local pig eradication pilot study was successfully implemented on a densely vegetated fenced 951 ha peninsula on Auckland Island, emulating the principles set out during the Santa Cruz Island (California, USA) eradication. We applied multiple techniques, each delivered at the appropriate pig population density and within a finite period, to reduce the inherent risk of eradication failure. Aerial hunting was used to reduce the pig population before systematic ground hunting by a team using specially trained dogs removed survivors and validated eradication success. The deployment of a high specification thermal or forward-looking infrared (FLIR) camera in a particular manner greatly improved the efficiency of aerial hunting during this pilot study. The use of passive trapping, Judas pigs and division of the island into smaller fenced units are supplementary methods proposed for the Auckland Island eradication to enhance eradication efficiency as the methods implemented here are scaled up.
{"title":"A local eradication pilot study of methods for feral pig eradication on Auckland Island","authors":"Finlay Cox, S. Horn, W. Bannister, Norma. MacDonald","doi":"10.20417/nzjecol.47.3490","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3490","url":null,"abstract":": Since their liberation in 1807, feral pigs ( Sus scrofa ) have negatively impacted ecosystem health and processes on subantarctic Auckland Island, New Zealand. Eradication of invasive alien species is often critical to restoration programmes and preventing species extinctions. Eradication programmes utilising multiple techniques have allowed feral pig eradications on large islands. Protracted eradication programmes can have a higher risk of failure due to factors such as biological, logistical, social, and funding support. A temporary local pig eradication pilot study was successfully implemented on a densely vegetated fenced 951 ha peninsula on Auckland Island, emulating the principles set out during the Santa Cruz Island (California, USA) eradication. We applied multiple techniques, each delivered at the appropriate pig population density and within a finite period, to reduce the inherent risk of eradication failure. Aerial hunting was used to reduce the pig population before systematic ground hunting by a team using specially trained dogs removed survivors and validated eradication success. The deployment of a high specification thermal or forward-looking infrared (FLIR) camera in a particular manner greatly improved the efficiency of aerial hunting during this pilot study. The use of passive trapping, Judas pigs and division of the island into smaller fenced units are supplementary methods proposed for the Auckland Island eradication to enhance eradication efficiency as the methods implemented here are scaled up.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47573139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3487
M. Trotter, M. Willis
: Farm livestock and other animals were introduced onto the Auckland Islands during the 19th century. Most were eradicated by the late 20th century, but before then, some goats ( Capra aegagrus hircus ), rabbits ( Oryctolagus cuniculus ), cattle ( Bos taurus ) and pigs ( Sus scrofa ) that were considered to have unique genetic characteristics were taken to mainland New Zealand with a view to studying and maintaining their particular breeds. Goats were liberated on the Auckland Islands on several occasions but those that survived to the late 20th century probably came from a group left on Auckland Island in 1865. In 1986 and 1987 some of these goats were taken to the South Island of New Zealand but were not maintained. Those goats left on Auckland Island were eradicated by 1992. Enderby Island rabbits came from a group of silver-greys that were released there in 1865. Forty-nine of them were captured and taken to Wellington in 1992, the rest were eradicated the following year. Breeding groups representing these rabbits are maintained in New Zealand today, but their numbers remain below the threshold required to ensure survival of the breed. Cattle were taken to the Auckland Islands in 1850 but appear not to have survived. A later introduction onto Enderby Island in 1896 fared better, though their numbers were never great. Semen was taken from 16 bulls at the time of their culling in 1991 and preserved, but oocyte removal from 11 cows at the same time was unsuccessful. A single surviving cow (‘Lady’) and her calf were rescued in 1993, but the calf later died. A number of Lady’s descendants have subsequently been produced in New Zealand through cloning, embryo transfer and natural mating. Pigs had been left on Enderby Island in 1807 and were reported to be on Auckland Island in 1840. Seventeen from Auckland Island were captured in 1999 and brought back to New Zealand where the breed has proved to be a valuable source of medical products.
{"title":"Introduction, rescue, and subsequent history of Auckland Islands livestock","authors":"M. Trotter, M. Willis","doi":"10.20417/nzjecol.47.3487","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3487","url":null,"abstract":": Farm livestock and other animals were introduced onto the Auckland Islands during the 19th century. Most were eradicated by the late 20th century, but before then, some goats ( Capra aegagrus hircus ), rabbits ( Oryctolagus cuniculus ), cattle ( Bos taurus ) and pigs ( Sus scrofa ) that were considered to have unique genetic characteristics were taken to mainland New Zealand with a view to studying and maintaining their particular breeds. Goats were liberated on the Auckland Islands on several occasions but those that survived to the late 20th century probably came from a group left on Auckland Island in 1865. In 1986 and 1987 some of these goats were taken to the South Island of New Zealand but were not maintained. Those goats left on Auckland Island were eradicated by 1992. Enderby Island rabbits came from a group of silver-greys that were released there in 1865. Forty-nine of them were captured and taken to Wellington in 1992, the rest were eradicated the following year. Breeding groups representing these rabbits are maintained in New Zealand today, but their numbers remain below the threshold required to ensure survival of the breed. Cattle were taken to the Auckland Islands in 1850 but appear not to have survived. A later introduction onto Enderby Island in 1896 fared better, though their numbers were never great. Semen was taken from 16 bulls at the time of their culling in 1991 and preserved, but oocyte removal from 11 cows at the same time was unsuccessful. A single surviving cow (‘Lady’) and her calf were rescued in 1993, but the calf later died. A number of Lady’s descendants have subsequently been produced in New Zealand through cloning, embryo transfer and natural mating. Pigs had been left on Enderby Island in 1807 and were reported to be on Auckland Island in 1840. Seventeen from Auckland Island were captured in 1999 and brought back to New Zealand where the breed has proved to be a valuable source of medical products.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":" ","pages":""},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42461481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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