Prioritising seabird restoration following predator eradication on islands

Seabird recovery can be rapid after predator eradication on islands, but it also can not be rapid at all. We investigated spatial and ecological influences on seabird recovery to islands following the eradication of introduced predators our paper: A GIS-based decision-making approach for prioritising seabird management following predator eradication, published in Restoration Ecology..

We used a large dataset of seabird census estimates on 69 islands in the Hauraki Gulf, Aotearoa. The region is a seabird diversity hotspot, supporting breeding populations of 27 seabird species and has a long history of predator invasion and eradications.

These data, along with ecological data that is specifically related to habitat preferences of seabirds and behavioural parameters were used in GIS-MCDA (geographic information systems – multi criteria decision analysis) to evaluate the constraints on recovery following predator eradications.

We identified nine islands with low observed passive recovery of seabirds post-eradication over a 50‐year timeframe, and classified these as sites where active seabird management could be prioritized. Such spatially explicit tools are flexible, allowing for managers to choose case‐specific criteria such as time, funding, and goals constrained for their conservation needs. Furthermore, this flexibility can also be applied to threatened species management by customizing the decision criteria for individual species’ capacity to passively recolonize islands. On islands with complex restoration challenges, decision tools that help island restoration practitioners decide whether active seabird management should be paired with eradication can optimize restoration outcomes and ecosystem recovery.

You can get a PDF here.

Islands identified in our GIS-Multi criteria decision analysis as sites suited for active seabird restoration following predator eradication.
Islands identified in our GIS-Multi criteria decision analysis as sites suited for active seabird restoration following predator eradication.


Intractable: species in New Zealand that continue to decline despite conservation efforts

My colleagues and I recently published an article in the Journal of the Royal Society of New Zealand about the intractables; species that continue to decline despite conservation action.

The lovely seabird Toanui/flesh-footed shearwater featured among the intractables. Toanui feeds mainly on squid and fish and the New Zealand colonies of the species represent 16 % of the global population. Since the 1930s, at least four New Zealand colonies have Screen Shot 2019-05-20 at 13.38.44vanished. Rats may be to blame, however, even on rat-free islands the population is decreasing. It is likely that the birds suffer from high levels of mortality from fisheries bycatch, as well as plastic pollution, which has been found in the digestive tracts of birds and chicks. In New Zealand the birds have been a low priority for conservation funding, however, predictions are the local population will be halved by 2050.

Other examples of intractables include the Māui dolphin, Pīngao, kākahi, forest ringlet butterfly, hihi, and the grand and Otago Skinks. We argued that some of these species are headed for extinction if no additional actions are taken. We may be leaders in conservation in Aotearoa New Zealand, but that doesn’t mean we can rest on our laurels.

Our article featured in the New Zealand media at the Newsroom, and Stuff.


Global biodiversity loss is accelerating at an alarming rate. While considerable effort and resources have gone into conservation management for many threatened species in New Zealand (NZ), some species are still ‘losing the battle’ despite much effort, and others have been ignored altogether. Here, we present seven case studies to illustrate the breadth of complex, often ambiguous, threats faced by taxa in NZ. These threats originate from the effects of agriculture and harvesting, irreversible habitat modification and loss, impediments to connectivity, disruption of parasite–host relationships, introduced species and susceptibility to disease, and are further exacerbated by complexities of political and legal inertia, low prioritisation and limited conservation funding. We outline the conservation challenges and identify advances needed to meet NZ’s long-term conservation goals. The next 30 years of conservation require new tools in order to protect especially those ‘intractable’ species that have thus far defied efforts to ensure their survival.

Read the full article.


Six Main Threats are Driving the Decline of a Remarkable Seabird Family

Seabirds are top predators, making them crucial indicators of the health of a marine ecosystem. And, they are sending us an alarming message–seabird populations have declined faster than other bird taxa over recent decades. Shearwaters and petrels are one of the most endangered groups of seabirds. These remarkable species are characterized by long ocean journeys for migration and feeding, and a dependence on islands to safely breed and raise young. This dual lifestyle places them at risk from many human-generated pressures.

These pressures on land and at sea have led to a poor conservation status for many of the 124 species of petrels with 52 (42%) threatened species and 65 (52%) suffering population declines. In our review in Frontiers in Marine Science,  38 petrel researchers from 34 institutions and 10 countries reviewed the future directions in conservation and research on petrels and shearwaters.

The study looked at information gaps that must be filled to improve the conservation and management of petrels. The researchers found crucial knowledge gaps on basic information required for their conservation, such as the location of breeding or wintering areas, or their migratory routes.We found that six main threats are the drivers behind global seabird declines.

Threats to petrels sorted by the number of species affected according to BirdLife International (2018)

“These seabirds are highly adapted marine animals as they are found across all the world’s oceans. But they must return to land to breed, usually on isolated and inaccessible islands. This isolation alone has not been enough to protect them from the global threats that are deteriorating the state of health of the seas” says Dr Andre Chiaradia, another leading author in this study from the Phillip Island Nature Parks, home of 1.4 million of short-tailed shearwaters.

The researchers believe that improving conservation status is possible if we can reverse some of the main six threats. “Some of these measures are the elimination, control and prevention of invasive species, restoration of breeding habitats, improvement of policies and regulations at the global and regional level, and the participation of local communities in conservation efforts such as seabird rescue campaigns” adds Dr Rodriguez, the lead author on the study.

“These results provide hope for these two globally important seabird groups. Knowing the primary threats allows us to take action to prevent further decline and save these species from disappearing forever. Invasive species like feral cats and rats are a key threat at breeding colonies. By removing invasive species like feral cats and rats from seabird islands, we can ensure safe breeding habitat and the opportunity for these remarkable species to once again thrive,” said Dr. Nick Holmes, a co-author on the paper and Director of Science at Island Conservation.

The clear message that emerges from this review is the continued need for research and monitoring to inform and motivate effective conservation for seabirds at the global level.



[citation] Rodríguez A, Arcos JM, Bretagnolle V, Dias MP, Holmes ND, Louzao M, Provencher J, Raine AF, Ramírez F, Rodríguez B, Ronconi RA, Taylor RS, Bonnaud E, Borrelle SB, Cortés V, Descamps S, Friesen VL, Genovart M, Hedd A, Hodum P, Humphries GRW, Le Corre M, Lebarbenchon C, Martin R, Melvin EF, Montevecchi WA, Pinet P, Pollet IL, Ramos R, Russell JC, Ryan PG, Sanz-Aguilar A, Spatz DR, Travers M, Votier SC, Wanless RM, Woehler E and Chiaradia A (2019) Future Directions in Conservation Research on Petrels and Shearwaters. Front. Mar. Sci. 6:94. doi: 10.3389/fmars.2019.00094

Plastic poses biggest threat to seabirds in New Zealand waters, where more breed than elsewhere

File 20180717 44097 i0v.jpg?ixlib=rb 1.1
The Northern Royal Albatross is one of many species of seabird that breed in New Zealand, from, CC BY-SA


Plastic pollution has the potential to cause the worst damage to seabirds in the seas around Aotearoa New Zealand, where many of them come to feed and breed.

Aotearoa boasts the greatest diversity of seabirds in the world. Of the 360 global seabird species, 86 breed here and 37 are endemic, which means they breed nowhere else.

Some 90% of New Zealand’s seabirds are threatened with extinction. They (and many other marine species) are under pressure from pollution, climate change, and overexploitation of marine resources. Plastic pollution could be the final nail in the coffin for many seabirds that are already struggling for survival.

Plastic – not so fantastic

Every week, another grotesque story illustrates the impact of plastic in the environment. A whale was recently found with 80 plastic bags in its stomach – it died, of course.

One-third of marine turtles have died or become ill due to plastic ingestion in Aotearoa New Zealand.

A 2015 study suggested that 99% of seabirds would be ingesting plastic by 2050. The authors also predicted that seabirds in our backyard, the Tasman Sea (Te Tai o Rēhua) would be the hardest hit, because of the high densities of seabirds foraging in the region, and the overlap with plastic. This not that surprising, given that the earliest observations of Aotearoa’s seabirds ingesting plastic go back to 1958.

The Chatham Island albatross feeds in the Southern Ocean and breeds only on The Pyramid, a large rock stack in the Chatham Islands, New Zealand.
Stephanie Borrelle, CC BY-SA

Sentinels of ocean plastic pollution

Seabirds are particularly vulnerable to ingesting plastics because most species feed at or near the ocean surface. They forage along eddies and oceanic convergence zones – the same areas where marine plastics accumulate. The impacts of plastic on seabirds and other marine wildlife include death by entanglement. Ingested plastic can inhibit a bird’s feeding capacity, leading to starvation or internal ulcers, and eventually death.

Flesh-footed shearwater populations in Aotearoa may have declined up to 50% to around 12,000 pairs since the 1980s, and have gone extinct at some of their Hauraki Gulf breeding sites. These declines continue in spite of predator eradication and an end to harvesting on many of the islands where they breed.

Autopsies of birds caught in fisheries in Aotearoa’s waters show flesh-footed and sooty shearwaters are more likely to contain plastic fragments than other species. Plastic fragments found in New Zealand flesh-footed shearwater colonies showed a linear relationship between the number of nest burrows and plastic fragments, indicating that plastic ingestion may be a driver in their population decline.

Toxic plastic soup

In Australia, up to 100% of flesh-footed shearwater fledglings contained plastic, the highest reported for any marine vertebrate. Fledglings with high levels of ingested plastic exhibited reduced body condition and increased contaminant loads.

The chemical structure of plastics means that they act as toxin sponges, attracting harmful contaminants from the surrounding seawater, including persistent organic pollutants and heavy metals. When an animal ingests plastic, there is the potential for those toxic chemicals to leach into its tissues.

Chemicals such as PCBs and flame retardants that are added to plastics during manufacture have been found in seabird tissue around the Pacific. High concentrations of toxic chemicals can retard growth, reduce reproductive fitness and, ultimately, kill.

Sooty shearwater (tītī) chicks, which are harvested and consumed by Māori in Aotearoa, have a high potential for ingesting plastic, given evidence of plastic ingestion in shearwaters from Australia and anecdotal evidence from harvesters on Stewart Island (Rakiura). The closely related short-tailed shearwater, which breeds in Australia, has also been show to consume plastic. In one study, 96% of chicks contained plastics in their stomachs and chemical loads in their tissue.

Ocean health and human health

Few, if any, studies have specifically looked at contaminant loads derived from plastics in any species of seabird in Aotearoa. However, Elizabeth Bell from Wildlife Management International is now collecting samples of preen glands, fat and liver tissue for analysis of toxic chemicals in bycatch birds found with plastic inside them. This research is crucial to understanding the implications of the transfer of toxins to people from harvested species that ingest plastic.

Seabirds are the sentinels of ocean health. They tell us what we can’t always see about the health of the oceans and its resources that we rely on.

Plastics are sold to us on the perceived benefits of strength, durability and inexpensive production. These qualities are now choking our oceans.

In a few decades, we have produced an estimated 8.3 billion tonnes. The expedited pace of production has not been met with adequate waste management and recycling capacity to deal with it all. As a result, an estimated 8 million tonnes of plastic pollute the environment each year.

Global production of plastics is doubling every 11 years. It is predicted to be an order of magnitude greater than current production levels by 2040. The time is ripe for the initiation of an international agreement to lessen plastic pollution in the world’s oceans and save our seabirds and marine wildlife.

Stephanie B. Borrelle, Conservation Ecologist, Auckland University of Technology

This article was originally published on The Conversation. Read the original article.

Linking plastic ingestion research with wildlife conservation

Plastic pollution is a ‘wicked problem’ – that is ‘a problem whose social complexity means that it has no determinable stopping point’. We can see action on stemming the flow of plastic into the ocean is gaining traction, but we need to recognise the problem is already here. So, how do we manage species conservation in a plasticene world?

I recently co-authored a paper in Science of the Total Environment (PDF here) about why and how we need to be better at linking plastic ingestion research with wildlife conservation, so that we can build tools to better manage the impacts of plastic ingestion on vulnerable species, like seabirds.


Plastic is an increasingly pervasive marine pollutant. Concomitantly, the number of studies documenting plastic ingestion in wildlife is accelerating. Many of these studies aim to provide a baseline against which future levels of plastic ingestion can be compared, and are motivated by an underlying interest in the conservation of their study species and ecosystems. Although this research has helped to raise the profile of plastic as a pollutant of emerging concern, there is a disconnect between research examining plastic pollution and wildlife conservation. We present ideas to further discussion about how plastic ingestion research could benefit wildlife conservation by prioritising studies that elucidates the significance of plastic pollution as a population-level threat, identifies vulnerable populations, and evaluates strategies for mitigating impacts. The benefit of plastic ingestion research to marine wildlife can be improved by establishing a clearer understanding of how discoveries will be integrated into conservation and policy actions.



Figure design by Jessie Borrelle @Moreorlessie


I love to vote.

When I vote, when you vote, when we vote, our individual voice is captured and aggregated in the representatives we choose to empower. Our votes divine how we choose to treat our most vulnerable peoples, and care for our environment. In the simple action of voting, we formalise our aspirations for our future and for the future of our children – to the best of our abilities given the options.

The reason I, a woman, am able to vote in elections, to be a part of the discourse on the way our society is constructed and run is because of the women in history who marched in the streets for equality of rights. Our democracy has come a long way since the suffragists began this march for equality, but it is naive to believe that we have progressed as far as we would like to think.

What does this have to do with marching for science?

One of the most incredible things about the human species is consciousness and reflection, which not only enables us to carry out the scientific method of discovery, but change and grow our minds in response to new information.

As a society, we have achieved things that were once thought of as fanciful – people have walked on the moon, we see beyond our galaxy, we have cured debilitating and deadly diseases, and the rest….our quality of life is the highest in history (for most) – thanks to the scientific method.

Scientists are people. People make societies; societies are constructed, run and improved by evidence-based knowledge, but only when all citizens are the beneficiaries of diverse and inclusive advances.  Science and society are a big beautiful interconnected network. If there is inequality in science, our science isn’t the best it can be, and if science is ignored, society suffers, we suffer.

In these current political climes, we are reminded daily that knowledge is powerful, and those that hold knowledge hold power. We see the best evidence of this under the Trump administration. The 45th president’s policy appears to be: holding truth hostage, blatantly refusing to give science a voice in policy, shutting down international scientific programs, and muzzling scientists from sharing publicly funded science with the community (particularly climate change, women’s health and vaccines).  This socio-political experiment has frightening implications. We are not immune in New Zealand – you only have to look at the Land and Water forum to open the discussion about the government ignoring the advice of scientists on the sad state of water quality due to dairy intensification.

The transition from evidence-based to value-based policy can a subversive and quiet one. The question is then – are we as New Zealander’s willing to close our eyes while a few individuals make the rules according to their own needs, based on their own values, ignoring the scientific evidence and the bigger picture? Are we willing to waste the progress that the suffragettes and scientists – our Hidden Figures: Beatrice Hill Tinsley’s, Rosemary Askin’s, Kathleen Curtis’, Edith Farkas’, Constance Helen Frost’s et al – fought for, to lose the inroads they made towards equality in science and in society? I’m joining my predecessors in taking to the streets to to march for equity and reason.

I am marching for science because inclusiveness for all peoples and inclusion of science in society and governance is a common sense double down.

I am marching for science because we are science – ever-evolving experiments in understanding.


Cross posted at

Seabird recovery post-predator eradication

Millions of dollars are spent on removing predators from offshore islands in the aim of protecting seabirds and island biodiversity. However, post-eradication monitoring is limited, so our understanding of how and if seabirds and their island habitats recover is also limited. In this paper, we investigated the recovery of seabirds to islands in the Hauraki Gulf, New Zealand to try and contribute to understanding these recovery processes better. The paper was published in the journal Oryx and you can find a PDF here!


Protecting seabirds is a global conservation priority
given that 29% of seabird species are threatened with extinction.
One of the most acute threats to seabirds is the
presence of introduced predators, which depredate seabirds
at all life stages, from eggs to adults. Consequently, eradication
of invasive predators has been identified as an effective
and commonly used approach to seabird conservation.
Seabird recovery following the eradication of predators is influenced
by complex and interacting environmental and
demographic factors, and there are gaps in our understanding
of species-specific responses. We reflect on the recovery
of seabirds on islands cleared of predators, drawing on the
equilibrium theory of island biogeography, and synthesize
key influences on recovery reported in the literature. We
present a regionally specific case study on the recovery of
seabird colonies (n = 98) in the Hauraki Gulf, New
Zealand, which is a hotspot of seabird diversity (27 species),
with a long history of eradications of invasive predators. We
found that on islands cleared of predators seabirds recover
over time, and such islands have more diverse seabird assemblages
than islands that never had predators. Recovery
appears to be influenced by a suite of site- and species-specific
factors. Managers may assume that given enough time
following eradication of predators, seabirds will recolonize
an island. Although time is a factor, proximity to source
populations and human activities has a significant effect
on recolonization by seabirds, as do demographic traits, colonizing
ability and habitat suitability. Therefore, integrating
expected site and species-specific recovery responses in the
planning of eradications should help guide post-eradication
management actions.



Fascinating facts about seabirds

If seabirds spend days, months or years at sea, how do they sleep? I talked to Jesse Mulligan at Radio New Zealand to answer that question and more about the fascinating lives of seabirds that make our country home. You can listen to the full interview here:



Pie in the Sky PHD projects: Remote sensing and burrow nesting seabirds

One of the most acute threats to seabirds is introduced predators, which depredate seabirds at all life stages from eggs to adults. Consequently, predator eradication has been identified as an effective and commonly used seabird conservation method. Seabird recovery post-eradication is influenced by complex and interacting environmental and demographic factors, though gaps remain in our understanding of the speed at which ecosystems respond to seabird recolonization. While monitoring seabird colonies post-eradication can help improve this understanding, limited resources and the remoteness and number of seabird islands challenge our ability to achieving long-term monitoring and research objectives. Therefore, economical and effective monitoring tools are needed.

Remote sensing has been used for decades in agriculture to evaluate crop nutrient status. Advances in remote sensing tools have improved the quality and reliability of applying this technology to evaluate a range of ecological systems. Seabirds can introduce large quantities of guano, effectively fertilising their island habitats. Concentrations of ammonia in soils have been positively correlated to seabird burrow density, and deposition rates of nitrogen into low nesting density systems can be as much as 3 times the rate of standard agricultural fertilisation rates.

Our research investigates if methods used for evaluating crop nutrient status on agricultural fields can be applied to a heterogeneous forest canopy. In this way, remote sensing could be used forDron monitoring long-term changes in seabird nesting density by evaluating canopy nutrient status. To test this hypothesis, we are investigating the relationship between seabird burrow density, and soil nitrogen and canopy level nitrogen on islands in the Mercury Island group, off the east coast of the Coromandel. We used a UAV (unmanned aerial vehicle) mounted multispectral sensor to collect extremely high resolution images (5cm).

This imagery is used to evaluate canopy composition and the spectral reflectance signature of pōhutukawa (Metrosideros excelsa), in relation to seabird density. We sampled and analysed soil and leaves from pōhutukawa trees on Korapuki (18 ha), Middle (13.5 ha), Green (2.5 ha), and Great Mercury (1867 ha) islands for total nitrogen and carbon:nitrogen ratios. Seabird nesting density on the islands ranges from low (1 burrow/m2) to high (10 burrows/m2).

As expectedpohutu, we found a strong relationship between seabird nesting density and soil nitrogen. However, our preliminary results indicate this relationship is not strongly transmitted to the canopy of pōhutukawa (Journal of non-significant results?). This result may be attributed to the physiology of pōhutukawa, which is a highly stress tolerant species. Pōhutukawa distribution is predominantly coastal, trees must be adapted to salt spray, arid environments, poor quality soils, often establishing on rocky steep cliffs. We postulate that given these stress tolerant adaptions, pōhutukawa may uptake and store only the nutrients it requires for growth and homeostasis, and perhaps is limited by other resources, so is not responding to nutrient enrichment in a way that is detectable in canopy spectral reflectance.

With these results in mind, our research continues to evaluate the spectral response of other island canopy species to seabird nutrient enrichment, and the topographic and environmental mahoeinfluences that might affect forest canopy reflectance. In the coming field season, we will be evaluating the canopy species māhoe (Melicytus ramiflorus) and milk tree (Streblus banksii) to compare the results of pōhutukawa with and identify other species that may act as proxies for evaluating seabird nesting density changes over time.

Predator eradication is an effective tool for protecting New Zealand’s seabirds. However, to ensure that seabirds populations are stable or increasing in the face of additional threats, such as fisheries and pollution, long-term monitoring is needed. Developing methods using remote sensing technology provides the opportunity to achieve these goals in an affordable way, across larger spatial scales than has been previously possible.


World Environmental Education Conference | Göteborg, Sweden

In June/July I was in Göteborg, Sweden for the World Environmental Education Congress. It is a beautiful city.

I’ll admit, initially I felt a little out of my element…. I am conditioned to conservation scientists, who, in all honesty are a bunch of ridiculously fun nerds. No, here there are educators, teachers, lecturers, and students [who are also a bunch of ridiculously fun geeks, just different]. It’s a rag tag bunch of folk who are undoubtedly the most important people in the world. I state that boldly, because these educators are at the coalface of hope for the future. They teach environmental literacy. Inspiring the next generation of scientists, architects, business people, and the rest about the wonder of the natural world. Informing the world’s students what in means to be alive on this planet today.

Why was I there then? well, I presented to the education world the Global Change app. A little project myself and some colleagues have been working on about plants, carbon, water and climate change – my aim is to give stomata the 15 minutes of fame to which they are so deserving of. The app was well received and there were lots of interesting and insightful conversations about the environment and the state of education and how tools, such as the app can enhance learning pathways.

I left the conference with a renewed sense of hope, there is an enormous community of educators, researchers, scientists and students working to improving environmental literacy. The next generations of students will have greater understanding, connection and appreciation for the natural world thanks to this community. It was an honor to be in the company of such a wonderful group of people.