In order to understand whether and if so which predators were contributing to an apparent decline in the numbers of Fiordland crested penguins, the West Coast Penguin Trust embarked on a four year study using trail cameras in 2014.
For the 2019 season, which followed a ‘mega-mast’ seed event and predicted rat and subsequently stoat population explosions, the Trust established an annual breeding success monitoring programme.
In 2020, following a mega mast in Autumn 2019, the Trust has extended the project, with the support of Wellington Zoo and the Birds New Zealand Research Fund, with the aim of better understanding whether breeding success is adversely affected by the presence of stoats, and if so, what is the best means to manage that threat.
An overview of the work planned for the 2020 season is available on the Birds NZ website and a summary of the 2019-2020 seasons is here and the full report here.
There were many fewer stoats than expected and predation was low, which was great for the penguins and showed us that there is plenty more to learn about the relationship between beech mast events, stoat populations and predation. (Interim reports on the 2020 season can be found here (March) and here (June).)
The Trust’s Tawaki Ranger and Trustee, Robin Long, gave this TED type talk in Franz Josef in October 2019, summing up the Trust’s work and her experience of tawaki both at home in Gorge River and volunteering with The Tawaki Project.
Robin has continued her adventures to survey areas of Stewart Island with a survey of the Port Pegasus coast in September 2020. A report of her mission can be found here.
Project Background
The Fiordland crested penguin, or tawaki, is in need of our help, being listed as Nationally Vulnerable and one of the least studied and rarest penguins.
Tawaki is the only crested penguin to inhabit the main islands and coasts of New Zealand. The 2012 IUCN red list classifies them as Vulnerable.
The West Coast Penguin Trust ensures that conservation management is based on good science.
Introduction
The Trust has set out to establish which predators may be contributing to a decline in the population so that appropriate targeted action can be taken. This follows a technical review of the conservation status of both the species and earlier management actions and a priority action was to determine the effects of introduced predators on the breeding success of tawaki.
A funding bid for a pre-predator control project to the Department of Conservation in 2014 was successful and motion activated cameras were purchased with sponsorship from local businessman, Geoff Robson of Greenstone Helicopters.
Cameras are a low impact method of obtaining the information and these were installed at two colonies at Jackson Head and Gorge River in South Westland, in late August for the four breeding seasons 2014-2017.
This work will ensure that any predator control targets the appropriate species in the most effective way, thus saving money and contributing to the conservation of the species in the longer term.
Four-year study
Our study coincided with a five-year study into the ecology and particularly the foraging ecology of tawaki by Dr Thomas Mattern and The Tawaki Project. We were able to share both resources and findings and the projects complemented each other extremely well at the Jackson Head site.
In the second year of the study, 2015, El Niño conditions off the West Coast resulted in almost complete nest failure at Jackson Head as chicks starved and adults swam up to 100km for little food and poor nutrition.
In the third year, 2016, stoats, which had been scarce, appeared in large number at the Jackson Head site and both eggs and chicks were lost to predation.
A fourth year in 2017 found breeding back to ‘normal’ levels, without El Niño conditions and with barely any stoats visible on camera footage.
Link to study report after 2017 season
With two abnormal years in the four-year study, but it appears that the large numbers of stoats and the loss of chicks was a direct result of an earlier beech seed mast event close by. These events, when trees produce massive amounts of seed every 2- 6 years, result in explosions in mice and rat populations, followed by stoats. As the food source for stoats runs out – as the seeds rot and germinate and rodent numbers reduce – stoats are likely to spread out in search of food. We believe they spread to Jackson Head in 2016.
The report at the end of the fourth year is here: WCPT Tawaki report 2018 Final
Shift of focus from predators to breeding success while assessing presence of stoats
Stoats are clearly the main land-based predator of and threat to tawaki in South Westland although only in some years when stoat numbers are in plague proportions, apparently or likely linked to mast events.
The Trust has shared its findings with the Department of Conservation and is recommending that landscape predator control operations be managed to take tawaki into account. They have traditionally been focused on species such as kaka and mohua, and ensuring tawaki nesting areas are included is a tiny step to take as treatment areas are already including or could include such colonies.
In order to gain a better understanding of the situation, the Trust started an annual breeding success survey of nests in the three areas of our study in the 2019 season and, in addition for the 2020 season, carried out trail camera and tracking tunnel monitoring (overview here).
A variety of both research and management priorities have been identified for tawaki and the West Coast Penguin Trust is involved in progressing those priorities for the benefit of the species, working with both the NZ Penguin Initiative and The Tawaki Project. Have a look at The Tawaki Project site for up to date blogs and news of their project, now focused in Milford Sound and check out http://pengu.cam/ for some extraordinary video footage, recorded under water from the back of a penguin.
In 2019, the Trust focussed on two colonies while the NZ Penguin Initiative did some intensive monitoring at Jackson Head. Read their report in the NZ_Penguin_initiative_ReportQ1_2020.pdf where they expected an invasion by stoats following the major mast event in summer 2018/19, but which did not eventuate.
A 2021 tawaki season report – WCPT has been summarised by Trust Ranger, Linden Brown.
Find a report on the 2022 tawaki season here.
A review of all three seasons monitored for breeding success and stoat presence (2019- 2021) to date can be found here. The summary is as follows:
- Tawaki nests were monitored at three distinct colonies in South Westland for three years
- The aim was to determine breeding success at these colonies; determine if there were any trends year to year, or between the colonies; and to better understand the link between mast events and stoat populations and predation as well as to methods of predator control.
- Trail cameras and tracking tunnels were used to determine the presence of predators (especially stoats) within the colonies.
- Breeding success was high at all three colonies for all three years, with no obvious differences or trends between years or between colonies.
- Stoats were present at all three colonies at different times, however at low numbers, and are likely responsible for a few tawaki nest failures.
- The mast event of 2018-19 did not result in any observable increase in stoat numbers in the colonies in either the 2019 or 2020 seasons
- Lack of food did not appear to be an issue for breeding tawaki during the study period.
2023 tawaki season summary
- It was a surprising season for tawaki at all three of the colonies we monitor in South Westland. Dire results were anticipated due to the forecast arrival of El Niño conditions and our previous experience of the strong El Niño conditions that started in July 2015. However, possibly due to the El Niño arriving later, in September and well into the breeding season, and not being as severe, tawaki had a very successful season. (Handy short introductory video to El Niño and La Niño here from NIWA.)
- Ranger Sarah Kivi returned to the trust to undertake the monitoring at two sites, one each north and south of Haast. One site had 17 nest checks completed twice in the season with 28 eggs recorded on the first visit and the second visit showing 17 nests still occupied, one failed attempt and 18 chicks. Three of the nests included two healthy, similar-sized large chicks – highly unusual. The usual breeding strategy for crested penguins is to focus on the second hatched and larger chick, which is usually the only one to survive.
- The second site had 14 nest checks completed twice in the season, the first finding 13 nests occupied and 20 eggs, and the second check showing 14 nests occupied, two failed attempts, one nest not breeding, two nests with eggs and 13 chicks, and again highly unusually, three nests with two healthy, similar-sized large chicks.
- Our Gorge River site monitored by Catherine Stewart also reported a similar success story with nine nests of ten monitored with cameras successfully raising one chick to crèching. Double clutching – raising two chicks – was seen or assumed in a remarkable seven of the other 17 nests monitored, near the end of the chick guard phase. Eggs were not seen to have hatched at three nests monitored and established at the start of the season. The presence of two chicks was confirmed almost to fledging in four of these. However, no photo showed two chicks together with the parent to distinguish them from two chicks from separate nests crèching together. After the chick guard stage, tawaki chicks gather in groups or crèches with an adult or two keeping an eye on them while other adults forage.
- With 100% being one chick raised from each nesting attempt, the figure was 90-115% for Gorge River. For the other South Westland sites, the figure was 100% compared to 72-100% in 2022 and similar figures in 2019-2021. (We note that two nest checks over a season cannot give us accurate data, but they provide indicative breeding success rates.)
From small beginnings to National Advocacy: Protecting New Zealand’s threatened Sea Birds
Speaking on Valentine's Day, Inger introduced the trust's love for penguins, its history and its work with a special focus on the two West Coast penguins and the Westland petrel. Congress participants were able to see the little penguin or kororā in the 'meet the locals' section of Te Nukuao Wellington Zoo. She acknowledged the invaluable and much valued relationship with the Wellington Zoo Trust, Te Nukuao Tūroa o Te Whanganui a Tara.
The opportunity for zoos and aquaria to motivate conservation is huge and Inger had seen this done brilliantly while travelling in the US throughout the Monterey Aquarium.
"There was an interactive pretend real cost café with video responses to your food choices explaining the impact on the environment and better choices, incredible art works made from litter and messaging encouraging readers to help keep plastic out of the sea, to choose ocean-safe products, and illustrating how the aquarium walks the talk."
Te Nukuao Wellington Zoo also works hard to raise awareness of issues and encourage responsible behaviours, whether relating to managing waste or dog ownership, including their 'Save our kororā - Take the lead' campaign.
The support from the ICZ to include Inger at the conference to share the trust's story and encourage zookeepers to take on this awareness role was very much appreciated. The ICZ also raised donations for the trust's work through the registration process, which was a wonderful surprise.
