Pub Date : 2022-11-28DOI: 10.20417/nzjecol.47.3496
A. Glen, S. Howard, Paul Jacques, R. Sagar, Finlay Cox
: As a major threat to New Zealand’s biodiversity, feral cats ( Felis catus ) are the subject of planned eradications on a number of offshore islands, including Rakiura Stewart Island. We used camera traps to estimate population density of feral cats on the north-east coast of Rakiura, and to investigate their movement behaviour and detection probability. We also used camera footage to compare the consumption of two types of non-toxic sausage baits (chicken and rabbit) with a view to future use of toxic baits. Population density of feral cats was likely between 1 and 2 cats per km 2 . Non-target species (rats and possums) removed more than half the baits, greatly reducing bait availability for feral cats. Deer and birds (including kiwi) encountered baits but did not eat them. Cats had an apparent preference for chicken over rabbit baits, although small sample sizes prevent firm conclusions. Both bait types appeared to decline rapidly in palatability, and no baits were consumed by cats more than 5 days after deployment. Future trials and baiting regimes should consider ways to improve bait availability. Increased bait density, exclusion of rats and possums and/or more frequent replacement of baits will likely increase encounter rates by feral cats.
{"title":"Feral cats on Rakiura Stewart Island: population attributes and potential eradication tools","authors":"A. Glen, S. Howard, Paul Jacques, R. Sagar, Finlay Cox","doi":"10.20417/nzjecol.47.3496","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3496","url":null,"abstract":": As a major threat to New Zealand’s biodiversity, feral cats ( Felis catus ) are the subject of planned eradications on a number of offshore islands, including Rakiura Stewart Island. We used camera traps to estimate population density of feral cats on the north-east coast of Rakiura, and to investigate their movement behaviour and detection probability. We also used camera footage to compare the consumption of two types of non-toxic sausage baits (chicken and rabbit) with a view to future use of toxic baits. Population density of feral cats was likely between 1 and 2 cats per km 2 . Non-target species (rats and possums) removed more than half the baits, greatly reducing bait availability for feral cats. Deer and birds (including kiwi) encountered baits but did not eat them. Cats had an apparent preference for chicken over rabbit baits, although small sample sizes prevent firm conclusions. Both bait types appeared to decline rapidly in palatability, and no baits were consumed by cats more than 5 days after deployment. Future trials and baiting regimes should consider ways to improve bait availability. Increased bait density, exclusion of rats and possums and/or more frequent replacement of baits will likely increase encounter rates by feral cats.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46383972","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.47.3482
J. Russell, S. Horn, K. Broome
: New Zealand manages five island groups in the Southern Ocean New Zealand subantarctic region: The Snares (Tini Heke), Bounty Islands, Antipodes Islands, Auckland Islands (Motu Maha or Maungahuka) and Campbell Island / Motu Ihupuku. Charted by Europeans in the late 18th and early 19th centuries, their preservation commenced in the early 20th century and restoration in the late 20th century. Since 1984, eradications of six introduced mammal species (cattle Bos taurus , sheep Ovis aries , goats Capra hircus , rabbits Oryctolagus cuniculus , Norway rats Rattus norvegicus , and mice Mus musculus ) across five islands (Campbell, Antipodes, Auckland, Enderby and Rose) have taken place. The only introduced mammal species remaining in the New Zealand subantarctic region are pigs ( Sus scrofa ), cats ( Felis catus ) and mice on the main Auckland Island. Building on previous eradication work, from 2018 to 2020 the Department of Conservation undertook research and development to determine the feasibility and cost of a multi-species eradication programme on Auckland Island. The outcomes of the research programme not only inform eradication on Auckland Island, but have wider applicability to other eradication programmes throughout the Southern Ocean.
{"title":"Restoration of New Zealand subantarctic islands","authors":"J. Russell, S. Horn, K. Broome","doi":"10.20417/nzjecol.47.3482","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3482","url":null,"abstract":": New Zealand manages five island groups in the Southern Ocean New Zealand subantarctic region: The Snares (Tini Heke), Bounty Islands, Antipodes Islands, Auckland Islands (Motu Maha or Maungahuka) and Campbell Island / Motu Ihupuku. Charted by Europeans in the late 18th and early 19th centuries, their preservation commenced in the early 20th century and restoration in the late 20th century. Since 1984, eradications of six introduced mammal species (cattle Bos taurus , sheep Ovis aries , goats Capra hircus , rabbits Oryctolagus cuniculus , Norway rats Rattus norvegicus , and mice Mus musculus ) across five islands (Campbell, Antipodes, Auckland, Enderby and Rose) have taken place. The only introduced mammal species remaining in the New Zealand subantarctic region are pigs ( Sus scrofa ), cats ( Felis catus ) and mice on the main Auckland Island. Building on previous eradication work, from 2018 to 2020 the Department of Conservation undertook research and development to determine the feasibility and cost of a multi-species eradication programme on Auckland Island. The outcomes of the research programme not only inform eradication on Auckland Island, but have wider applicability to other eradication programmes throughout the Southern Ocean.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43489838","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.47.3484
Derek Brown, Finlay Cox
: Cattle ( Bos taurus ) were introduced to 11 268 ha Campbell Island/Motu Ihupuku in 1902 as part of a short-lived farming venture that was abandoned by 1931. The cattle were left to fend for themselves and a small feral population of 10–20 animals persisted for 53 years. The population was largely limited to a small area (c. 440 ha) of the island noted for its limestone geology. Ecological damage was pronounced with churning of the soil, damage to vegetation and probable impact on seabird nesting. Eradication was proposed for 1984 as a precursor to the fencing subdivision of the island for subsequent sheep eradication. Three cattle were shot in January 1984 and although 1–2 animals were known to have survived the cull, for unknown reasons these survivors died out shortly after, and no cattle were seen after winter 1984. Extreme weather events, poor recruitment, and competition with an increasing sheep population may have been partly responsible for the decline to local extinction. The ecological response has been significant but cannot be fully differentiated from the response to subsequent sheep and rat removal.
{"title":"The hunting-assisted demise of Campbell Island cattle","authors":"Derek Brown, Finlay Cox","doi":"10.20417/nzjecol.47.3484","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3484","url":null,"abstract":": Cattle ( Bos taurus ) were introduced to 11 268 ha Campbell Island/Motu Ihupuku in 1902 as part of a short-lived farming venture that was abandoned by 1931. The cattle were left to fend for themselves and a small feral population of 10–20 animals persisted for 53 years. The population was largely limited to a small area (c. 440 ha) of the island noted for its limestone geology. Ecological damage was pronounced with churning of the soil, damage to vegetation and probable impact on seabird nesting. Eradication was proposed for 1984 as a precursor to the fencing subdivision of the island for subsequent sheep eradication. Three cattle were shot in January 1984 and although 1–2 animals were known to have survived the cull, for unknown reasons these survivors died out shortly after, and no cattle were seen after winter 1984. Extreme weather events, poor recruitment, and competition with an increasing sheep population may have been partly responsible for the decline to local extinction. The ecological response has been significant but cannot be fully differentiated from the response to subsequent sheep and rat removal.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41432384","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.47.3498
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":null,"pages":null},"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.47.3491
Finlay Cox, Norma. MacDonald
: A feasibility study for removing feral pigs ( Sus scrofa ) from Auckland Island trialled feeders monitored by trail cameras to determine their effectiveness for detecting and attracting feral pigs. Ten automatic feeders were installed during January–February 2019 (summer) and again in August–September 2019 (winter) on Auckland Island. They delivered kibbled maize daily for a period ranging from 25 to 37 days. Sites selected for feeder installation needed to be of appropriate relief and area to allow feeder and trap installation, as would occur during an eradication operation. Feeder success varied across sites during the trial. Site selection where there was evidence of fresh pig presence improved the rate of visitation. Feeders offer significant efficiencies to lethal techniques such as trapping by automatically dispensing feed to allow constant supply over a long period. This automation reduces operator effort, but is also advantageous as consistent feed times train pigs to condition their visits so they can be more effectively targeted. In this trial, most visiting pigs returned to the feeder daily from around 15 days after installation. Automated feeders will be an integral component of the proposed methodology for Auckland Island pig eradication to target nocturnal individuals and family groups, and, importantly, reduce the risk of education through non-lethal engagement.
{"title":"Use of automatic feeders to attract feral pigs on Auckland Island","authors":"Finlay Cox, Norma. MacDonald","doi":"10.20417/nzjecol.47.3491","DOIUrl":"https://doi.org/10.20417/nzjecol.47.3491","url":null,"abstract":": A feasibility study for removing feral pigs ( Sus scrofa ) from Auckland Island trialled feeders monitored by trail cameras to determine their effectiveness for detecting and attracting feral pigs. Ten automatic feeders were installed during January–February 2019 (summer) and again in August–September 2019 (winter) on Auckland Island. They delivered kibbled maize daily for a period ranging from 25 to 37 days. Sites selected for feeder installation needed to be of appropriate relief and area to allow feeder and trap installation, as would occur during an eradication operation. Feeder success varied across sites during the trial. Site selection where there was evidence of fresh pig presence improved the rate of visitation. Feeders offer significant efficiencies to lethal techniques such as trapping by automatically dispensing feed to allow constant supply over a long period. This automation reduces operator effort, but is also advantageous as consistent feed times train pigs to condition their visits so they can be more effectively targeted. In this trial, most visiting pigs returned to the feeder daily from around 15 days after installation. Automated feeders will be an integral component of the proposed methodology for Auckland Island pig eradication to target nocturnal individuals and family groups, and, importantly, reduce the risk of education through non-lethal engagement.","PeriodicalId":49755,"journal":{"name":"New Zealand Journal of Ecology","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42999668","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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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}
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