Massey Research Online - Browsing by Author "Chilvers BL"

Browsing by Author "Chilvers BL"

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Diet plasticity and links to changing foraging behaviour in the conservation of subantarctic yellow-eyed penguins (Megadyptes antipodes)
(John Wiley and Sons, Ltd, 2022-05-17) Muller CG; Chilvers BL; French RK; Battley PF
1. Diet is a key factor affecting seabird foraging behaviour, ultimately influencing survival, breeding success and long-term population viability. The density and distribution of prey species in the marine environment are influenced by many factors including climate effects such as El Niño southern oscillation and climate change that alter water temperature. 2. While poor quality diet has been implicated as a contributing factor in the decline of some mainland New Zealand yellow-eyed penguin (Megadyptes antipodes) populations, little is known about their diet in the subantarctic where the majority of the species breeds. 3. Blood and feather samples (n = 63) were collected for stable isotope analysis of diet from 25 individual birds breeding on subantarctic Enderby Island, Auckland Islands, New Zealand, from 2015 to 2018. 4. Diet data were analysed by factors such as breeding year, sex and foraging behaviour. Stable isotope analysis demonstrated significant changes in diet during each year of the study, which included both El Niño and La Niña conditions. 5. Diet during El Niño conditions comprised lower trophic level prey, which were more benthic, and found closer to shore than diet during La Niña. 6. Coupled with the reported variable breeding success of yellow-eyed penguins in the subantarctic, variable diet suggests prey availability is likely to be a limiting factor in some years. Prey availability is therefore expected to be a major influence on survival and breeding success of this endangered species in the future, particularly if the effects of climate change become more pronounced. 7. This research highlights an urgent conservation need to identify prey species utilized by the southern population, along with their distribution in time and space, and therefore also the effect of diet on long-term population stability.
Earthquake impacts on a protected pinniped in New Zealand
(John Wiley and Sons, Inc., 2024-01-03) Hall AA; Chilvers BL; Weir JS; Boren LJ
The impacts of natural disasters on marine mammals are poorly understood and difficult to study, which can hamper management responses following such events. This study provides the first distribution and abundance assessment of New Zealand fur seal (NZFS: Arctocephalus forsteri) colonies around Kaikōura, New Zealand, since a 7.8 magnitude earthquake in November 2016 caused substantial changes to both the local marine and terrestrial environments, and led to the reconstruction of a major highway that runs adjacent to NZFS colonies. Mark–recapture and direct counts in the 2022–2023 breeding season estimated pup production for NZFS breeding colonies along the Kaikōura coast. Using established multipliers, pup estimates were used to provide the first comprehensive population estimate for Kaikōura's NZFS population since the earthquake. Three new colonies and three new subcolonies were assessed and recorded, additional to reassessments of two established colonies. Overall, Kaikōura's NZFS population has grown and spread post-earthquake, with an upper total population estimate of between 21,560 and 28,327 animals in the 2022–2023 breeding season. Some sites, such as Lynch's Reef, appear to have benefited from earthquake-induced coastal uplift, with pup production increasing. Contrastingly, the estimated 2,401 (±99) pups produced at Ōhau Point in 2023 is similar to pre-earthquake estimates. This indicates that the earthquake has disrupted previously documented growth at this site. The distribution of NZFS breeding at Ōhau Point has also changed substantially since the last pre-earthquake assessment. From these findings, alterations to the Ōhau Point New Zealand Fur Seal Sanctuary and similar protections at other locations on the Kaikōura coast are suggested, as greater numbers of NZFSs are now accessible to human interaction and disturbance. The results demonstrate both how natural disasters and subsequent infrastructure modifications can impact coastal species and how conservation measures may need to be amended accordingly.
Lessons Learned for Pre-Emptive Capture Management as a Tool for Wildlife Conservation during Oil Spills and Eradication Events.
(MDPI (Basel, Switzerland), 2023-02-24) Chilvers BL; McClelland PJ; Li C
Pre-emptive capture or translocation of wildlife during oil spills and prior to pest eradication poison applications are very specific conservation goals within the field of conservation translocation/reintroduction. Protection of wildlife from contamination events occurs during either planned operations such as pest eradication poison applications, or unplanned events such as pollution or oil spills. The aim in both incidences is to protect at-risk wildlife species, ensuring the survival of a threatened regional population or entire species, by excluding wildlife from entering affected areas and therefore preventing impacts on the protected wildlife. If pre-emptive capture does not occur, wildlife may unintentionally be affected and could either die or will need capture, cleaning, and/or medical care and rehabilitation before being released back into a cleared environment. This paper reviews information from pre-emptive captures and translocations of threatened wildlife undertaken during past oil spills and island pest eradications, to assess criteria for species captured, techniques used, outcomes of responses, and lessons learned. From these case studies, the considerations and planning needs for pre-emptive capture are described and recommendations made to allow better use and preparedness for pre-emptive capture as a preventative wildlife conservation tool.
Planning for an offshore oiled wildlife response: case studies from New Zealand and Brazil.
(Springer Nature, 2023-04-01) Chilvers BL; Ruoppolo V; Garrigues P
When an offshore oil spill occurs, it is often assumed that there will be no wildlife impacted or that an oiled wildlife response could not be undertaken. In most cases, one or both assumptions are wrong. With increasing offshore fishing, petroleum exploration, and shipping routes, the risk of accidents and spills offshore has increased. This review outlines the important considerations for offshore oiled wildlife response and explores two case studies on offshore oiled wildlife response planning based on offshore drilling or active platforms in New Zealand and Brazil. There are significant challenges for running a response in offshore environments; however, with planning, including preparation of specialized response plans, equipment, and readiness of skilled personnel, an offshore oiled wildlife response can lead to greater survival and protection for wildlife and the environment.
Post-earthquake highway reconstruction: Impacts and mitigation opportunities for New Zealand pinniped population
(Elsevier B.V., 2023-11-01) Hall AA; Chilvers BL; Weir JS; Vidulich A; Godfrey AJR
Knowledge of how roads impact wildlife populations is limited but required to inform management and mitigation. Prioritising sites for mitigation involves identifying the most at-risk areas and populations, particularly after substantial changes to roading infrastructure. We identify hotspots for New Zealand fur seal (NZFS: Arctocephalus forsteri) incidents (live or dead NZFS) on State Highway 1 (SH1) around Kaikōura, on New Zealand's South Island, and analyse whether hotspot locations have persisted following earthquake-induced road reconstruction. We also assess spatial, environmental, and temporal influences of NZFS incidents. Spatial records of incidents along SH1 were analysed to identify contemporary and former hotspots using Kernel Density Estimation Plus and a Poisson-based method. Spatial, temporal and environmental data were collected to assess these factors’ effects on incident location and timing. Between 2012 and 2022, an average of 59 incidents were recorded annually along 90 km of SH1. Ten significant hotspots accounted for 89% of incidents, along 2.75 km of road. Hotspot concentration shifted following road reconstruction. Incident numbers were significantly positively associated with traffic volumes and windspeed, and significantly negatively associated with temperature and rainfall. Autumn experienced significantly more incidents than any other season. Road-abutting NZFS breeding areas explained most of the spatial variation in incidents. SH1 is a threat to Kaikōura's NZFS, with its effects changing following an earthquake impacting NZFS distribution, and associated highway reconstruction. Hotspot analysis and current road protections suggest the risks could be substantially reduced by barrier construction along short stretches of road. This type of assessment should continue as climate change raises sea levels and increases storm events globally. This analysis and mitigation approach could be used for any wildlife across numerous landscapes.
Techniques for hazing and deterring birds during an oil spill.
(Elsevier B.V., 2024-04-01) Chilvers BL
Preventing wildlife from becoming oiled is the priority in an oiled wildlife response. This is achieved through diverting spilled oil away from wildlife, or hazing, deterring, or excluding wildlife from oiled areas. This paper undertakes an international review of techniques deployed for hazing and deterring birds, the taxa most affected, during oil spills. Using these techniques as a baseline it then compares what techniques are used in New Zealand at airports, in agriculture, and at waste management facilities, to assess what could readily be deployed in New Zealand during oil spills, as currently there are few options planned for. As international literature suggests, the best technique is to use a variety of methods for targeted species to reduce habituation. This review highlights international practices that could be tested and implemented, to allow for planning for effective hazing and deterrence practices in New Zealand.
Variable breeding success and its implication in the conservation of endangered yellow-eyed penguin (Megadyptes antipodes) at the New Zealand subantarctic Auckland Islands
(John Wiley and Sons, Inc., 2024-04-19) Muller CG; Chilvers BL; French RK; Battley PF
Knowledge of breeding success is essential for conservation, as it is required for monitoring populations and survival trends. Seabird reproductive success can be negatively affected by prey availability, marine-based stochasticity, extreme weather events, individual breeders' performance and direct threats such as disease, predation and fisheries interactions. The endangered yellow-eyed penguin (Megadyptes antipodes) is declining in mainland New Zealand, however, little is known about its breeding success in the subantarctic where the majority of the species breeds. Yellow-eyed penguin breeding success data were collected from a total of 167 nests on subantarctic Enderby Island, Auckland Islands, New Zealand, from the 2015 to 2017 breeding seasons. This included egg and chick mortality and fledging rates, plus a wider sample of the fledgling condition of 276 chicks. Fledging success was higher than in mainland New Zealand in some years, although chicks were smaller and lighter on average, highlighting the need for more information on juvenile survival probabilities in the subantarctic. Breeding success measures were similar in 2015 and 2016, but a large egg mortality in 2017 caused a significant reduction in breeding success that year. Such variability requires more investigation into the correlates of breeding success, including possible stressors such as foraging success, adverse weather and environmental effects, and pathogens. These results demonstrate the need for ongoing monitoring of yellow-eyed penguin breeding success across the subantarctic in order to establish baselines for normal variation and to determine whether anthropogenic (manageable) factors may be contributing to low productivity. This research highlights an important consideration for endangered species conservation; that breeding success may not be consistent over time, or across a species' entire range. Additional monitoring of all breeding populations should be carried out to ensure up-to-date information is available to inform conservation management decisions for the species.
What Helps Oiled Wildlife Responders Care for Animals While Minimizing Stress and Compassion Fatigue
(MDPI (Basel, Switzerland), 2021-06-30) Yeung P; White B; Ziccardi M; Chilvers BL
Oil spills are environmental disasters and their long-term impact is not just a concern for the environment and economy, but also for first responders’ health and wellbeing. Wildlife, such as aquatic birds and certain marine mammals, are highly susceptible to physiological effects of oiling, and oiled wildlife responders are crucial to provide measures for their survival. The purpose of this research was to explore the experiences of oiled wildlife responders and what factors and conditions have helped or inhibited the responders to care-affected wildlife. This study collected responses (n = 50) from a survey of responders who attended either the New Zealand MV Rena or US Refugio pipeline oil spills. Study participants were mostly older (>40), highly educated females. We found there were significant differences in compassion satisfaction, resilience, burnout and overall satisfaction based on age, gender and role. While most responders have only attended limited numbers of oil spill incidents, they reported positive experiences and found it rewarding. Findings from responders indicated that to lessen stress and compassion fatigue during an incident, provision of training and support from professional organizations equips responders with knowledge and skills that can support their personal resilience to respond to disaster events.
Whisker stable isotope analysis used for proactive management of recolonising New Zealand sea lion population
(Inter-Research Science Publisher, 2023-10-26) Chilvers BL
New Zealand sea lions Phocarctos hookeri have experienced a 46% decline in pup production in the last 25 yr, driven by female deaths in trawl fisheries around the Auckland Islands. The only colony for this species recorded away from the subantarctics and this fishing impact is on Stewart Island. Despite the Stewart Island colony only being 1% of the species, it is significant, as it is currently the only stable population and is located in an area away from most on-land human impacts, although not away from potential fisheries pressures. To ensure this colony’s persistence, more information is needed on these sea lions’ diet, foraging behaviour, and local fisheries interactions for management that promotes their protection. The present research investigates the long-term foraging behaviour, and infers the diet, of female New Zealand sea lions on Stewart Island using their known foraging behaviour and linking this to their proximal and full-length whisker stable isotope values. Previous foraging studies found that these animals have small foraging areas with consistent mesopelagic diving behaviours. These behaviours, linked with their whisker stable isotope values, show consistency in foraging behaviour and in - ferred diet across their entire adult life. Currently, there are no known commercial fisheries bycatch issues for sea lions around Stewart Island. However, precautionary measures ensuring fisheries pressure does not increase and management to safeguard that deepwater trawling and finfish aquaculture remain absent would be proactive steps that should be undertaken for the protection of this new colony and for this Endangered species as a whole.

Browsing by Author "Chilvers BL"

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