ecology – Page 2 – Cabot Institute for the Environment blog

“Between the Insect Hordes and Ourselves”: Imaginaries of insect declines from the 1960s onwards

Posted on December 11, 2020April 4, 2023 by janet.crompton

A still from Bee Movie (2007), directed by Simon J. Smith and Steven Hickner

‘According to all known laws of aviation, there is no way a bee should be able to fly. Its wings are too small to get its fat little body off the ground. The bee, of course, flies anyway because bees don’t care what humans think is impossible.’ You might recognise these words as the opening from the animated film Bee Movie (2007). The film is as known for its memes as its compulsive heteronormativity. If you are unaware: not only are there many happy nuclear bee families, the star of the film, Barry, is a male worker bee. On top of that, the human woman with whom Barry takes on the honey industry and fights for equal bee rights appears to develop some warm feelings for him. Needless to say, Bee Movie is fun but not a cinematographic masterpiece.

Jokes aside, the 2007 film is a good indicator of an influx of documentaries, memoirs, novels, and poetry collections starring the Western or European honeybee. Perhaps I’m being too critical here. This influx does excite me in a way, as it shows that insect life and decline has become part of a broader conversation. But, with this awareness of insect decline in our cultural imagination comes a sting in the tale. In this case, the sting is an almost obsessive focus on the European honeybee in an age of overall insect decline and what Elizabeth Kolbert (2014) popularised as the sixth extinction. There are thousands of known species of bees all over the world—not to mention other bugs—and yet a select group of people continue to talk, write, film, draw and campaign for the European honeybee. (Are you familiar with the concept of bee-washing?)

In response to these stories, I started thinking about the following: why is there so much creative work on the honeybee? Insects make up the most biodiverse and largest class of described (and estimated) species in the animal kingdom. And while many of these—not all—are indeed facing decline or even extinction, the European honeybee is not one of them.

What started out as a general interest, quickly evolved—metamorphosed!—into my doctoral project on insect decline. Inspired by Ursula Heise’s (2016) work on the cultural side of extinction, I started asking the following: what kind of narratives do people create when talking about insect decline, and how do they tie in with other and older insect stories, our broader cultural memory? Is there an explanation to be found for this honeybee hyperfocus when it comes to narratives of insect decline? Thinking about these questions, I kept returning to Donna Haraway, who wrote that ‘it matters what stories we tell to tell other stories with … It matters what stories make worlds, what worlds make stories.’ (12) Haraway’s keen (if not overcited) observation also applies to the case of insect decline. When looking at creative storytelling—of which there is a lot—we’re not just considering entertainment or aesthetics. Even with something as seemingly banal as Bee Movie, it does matter what stories we tell to tell the story of insect decline. So why do people contribute to this, for lack of a better word, honeybee extravaganza?

An assortment of contemporary honeybee stories

My project become more than a chance to get deep into the problem with honeybees and other charismatic microfauna. Thinking about tiny critters (instead of charismatic megafauna) created the opportunity to engage with and tease out some of the broader questions in the fields of critical animal and extinction studies. Between all the reading and writing and talking and plotting out of the work that needs to be done, theories and ideas and random shower thoughts keep falling into place, and I have a red thread or two running through the different chapters of my thesis. Watch this space.

For now, I do want to say that one of the more rewarding elements of my research so far has been the deep dive into care ethics. My understanding of the concept has both expanded and gained new focus, and my deep dive into care and conservation has opened my eyes to the possibility of care as a violent practice (Salazar Parreñas 2018). One of my current challenges is to see how care, understood as ‘a vital affective state, an ethical obligation and a practical labour’ (Puig de la Bellacasa), is reflected in the poetics of insect decline. What does a poetics of care look like when we let ourselves become subject to, as Haraway (2008) phrased it, the ‘unsettling obligation of curiosity, which requires knowing more at the end of the day than at the beginning’ (36). What happens when we allow ourselves to pay careful attention to the other-than-human life around us and start to care?

Assorted Coleoptera in the University of Texas Insect Collection

Another thread is that of the different (temporal and spatial) scales of extinction and the limits of our empathy for other-than-human animals. As Ursula Heise (2016) and Dolly Jørgensen (2019) so effectively argue in their monographs on the topic, extinctions come to matter once they reflect upon our own (human) pasts, presents, and futures and we can emotionally engage with them. And like these different pasts, presents, and futures, extinction isn’t singular. It is easy—and to a certain extent even useful—to put it all under the label of the sixth extinction. Still, I am increasingly convinced that such labels obscure the differences and intricacies people need to be aware of in the face of the sixth extinction—or rather, extinctions.

There are local extinctions, global extinctions, extinctions completely missed or forgotten (by human eyes), even desired extinctions. Communities respond to and engage with different species and local and global extinctions in different ways. Especially when something tricky like shifting baseline syndrome ensures that some communities aren’t aware of local extinctions or declines in the first place, while passionate campaigns for charismatic megafauna put certain species on the global agenda and in the public eye. I’m not saying this is always a bad thing (I’m just as passionate about the survival of the Malayan and Sumatran tiger as the next person).

I am, however, saying that it is worth researching how attention and care are directed and, ideally, can be redirected in times of need. And insects—in all their creeping and crawling diversity, with important ecosystem functions such as pollination, prey, and waste disposal—have turned out to be an excellent group to consider these questions.

Sources

Haraway, Donna J. Staying with the Trouble: Making Kin in the Chthulucene. Duke UP, 2016.
—. When Species Meet. U of Minneapolis P, 2008.
Heise, Ursula K. Imagining Extinctions: The Cultural Meanings of Endangered Species. U of Chicago P, 2016.
Jørgensen, Dolly. Recovering Lost Species in the Modern Age: Histories of Longing and Belonging. MIT Press, 2019.
Kolbert, Elizabeth. The Sixth Extinction: An Unnatural History. Bloomsbury, 2014.
Puig de la Bellacasa, María. Matters of Care: Speculative Ethics in More Than Human Worlds. U of Minnesota P, 2017. Salazar Parreñas, Juno. Decolonizing Extinction: The Work of Care in Orangutan Rehabilitation. Duke UP, 2018

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This blog is written by Cabot Institute member Eline D. Tabak, PhD researcher in English (University of Bristol) and Environmental Humanities (BSU). This blog outlines her SWW DTP-funded project. You can follow Eline on twitter @elinetabak and see more of her writing and work at www.elinedtabak.com. This blog was reposted with kind permission from the Centre for Environmental Humanities. View the original blog.

Eline D. Tabak

Mourning auks: Creative expressions of extinction in an era of ecological loss

Posted on December 7, 2020March 31, 2023 by janet.crompton

Looking at your hearts, suspended in their jar, I try and imagine the two of you still alive. I know that if you were anything like your closest living kin, you would have bonded for life. You lived a long time, and it would have been a relationship that had gathered and deepened over years. By the time you came together this final time, the congregations that were so important to your kind were already a thing of the past. Perhaps you were aware of how empty your world had become. Although you were alone on that low rock, it could be that you were accompanied by the memory of the multitude that had once been. By this point it was already too late. There were too few of you to recover what had been lost. Even so, maybe you would have nodded to each other and tried to make the best of it. Maybe you would have started showing off, just as those before you had always done; turning your heads from side to side so the bright white around your eye would have caught the light. Maybe then, with an exuberance tinged with grief, you would have thrown your heads back and let out an ecstatic cry; the vivid yellow inside your mouths shining like a beacon, mimicking the sun.

Catastrophic anthropogenically-driven biodiversity loss is a defining problem of our time, with hundreds of extinctions observed every year, and many more occurring unnoticed. Reacting to the scale of this issue, extinction studies researchers have called for new interdisciplinary responses interrogating what extinction means, why it matters, and how it is narrated.

‘Mourning Auks’ is an innovative practice-led project examining how artful geographic methods and outcomes can contribute to these vital questions. Over the next four years I plan to explore what novel and affective modes of engaging with anthropogenically-driven species loss can be generated through creative articulations of the emotional dimensions of extinction, and how these can be communicated in public artistic and museum contexts.

In extinction studies, extinction is understood not as a singular, generic concept, but as something that exists through multiple specificities relatable to the diversity of lifeworlds being lost. This is generally explored via case studies, which employ critically-driven creative-academic storytelling to express the biological, cultural and temporal particularities of species, their unique phenomenal worlds, and the significance of extinction within multispecies entanglements. This narrative-based approach provides a form of witnessing that is attentive to others in the face of irreparable loss, that counters human exceptionalism, and creates new ethical and cultural modes that help to resist the destructive legacies of anthropogenically-driven extinction more broadly.

Unexplored potential exists for artistic methods to undertake and communicate these extinction-orientated case studies. Through a case study on the now extinct great auk, my practice-led project will explore and analyse ways of engaging broader audiences with this field. It aims to expand the affective reach of these essential attempts to re-articulate contemporary species loss, and its ethical and socio-cultural imperative.

Fig. 1 Alca Impennis by John Gould, from The Birds of Great Britain, Vol. 5 (1873). John Gould/Public Domain

The great auk was a flightless seabird that was once found in the cold coastal waters of the North Atlantic. These birds nested in huge social colonies on isolated islands, which they returned to every year. These remote skerries provided protection from terrestrial predators. However, they became increasingly vulnerable after technological advances in ocean-going vessels brought European sailors into close proximity to these breeding colonies, which they ruthlessly exploited for food on trans-Atlantic voyages.

My research will begin with analysis of the ‘Garefowl books’, a substantial, underexploited resource held in the Cambridge University Library collections. These manuscript diaries, kept by the Victorian ornithologist and egg collector John Wolley, record interviews with witnesses who were amongst the last to see the auks alive, and who took part in the final hunting parties to their breeding places. Close reading of this material will inform studio-based experimentation utilising artistic methods drawn from archival impulses in contemporary art (see the works of John Akomfrah and Tacita Dean, amongst many others). Following on from Brian Massumi’s 2014 book What Animals Teach us About Politics such ‘playful’ creative practices can be seen as animal in origin, and provide a continuum with animal life (see Merle Patchett’s Archiving). In this context, these textual encounters with the auk’s disappearance offer the means of both interrogating the socio-cultural practices that drove their extinction, and of generating sympathetic multispecies re-alignments.

I also plan to draw the narratives surrounding the auks’ disappearance into emotional geographic frames. These examine spatialisations of emotion in relation to landscape, including those relating to death, such as mourning and grief. Study here is mostly restricted to human contexts, and my project aims to develop this to explore the affective geographies of sites of extinction-driven absence.

Fig. 2 An eighteenth-century sketch of Geirfuglasker by Guðni Sigurðsson. Geirfuglasker, a now submerged volcanic island off the south coast of Iceland, was one of the great auk’s breeding colonies. National Museum of Iceland/Public Domain

In recent re-interpretations, avian philopatry has been re-conceptualised as other-than-human ‘storying-of-place’ (see Thom van Dooren’s excellent book Flight Ways). Hypothesising this for great auks gives their breeding sites potency as places, not just because they were invested with history and meaning for the auks, but because these became the traumatic sites of their extinction. In this context, I plan to undertake fieldwork at some of the auks’ historical breeding colonies, and at those of their closest living relatives. Here, imaginative curiosity towards these species’ remote, liminal, and aquatic geographies will inform a creative enlivening of the great auks’ historical lifeworld, providing the basis for further artistic experimentation centred on site-specific place-making exercises. These will attend to how landscapes are matters ‘of [other-than-human] biographies, attachments and exiles’ in which ‘absence, loss and haunting’ abound (Wylie, 2007: 10), and will survey the more-than-representational emotional aspects of extinction.

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This blog is written by Milo Newman, PhD candidate in human geography. This blog introduces his project on creativity and extinction. Milo’s research is funded through the AHRC South West and Wales Doctoral Training Partnership. You can follow Milo on twitter @_milonewman and see more of his work at www.milonewman.com. This blog has been reposted with kind permission from the Centre for Environmental Humanities. Read the original blog.

Milo Newman

Pollination and International Development: How bees can help us fight poverty and feed the world

Posted on June 19, 2018April 5, 2023 by janet.crompton

Animal pollinators are the industrious workers in the factory of life – transporting pollen from one flower to another to ensure successful fertilisation. 75% of our crop plants benefit from this free service which can increase the yield, quality and even shelf-life of their products. This translates to a US$235-577bn value to global agriculture each year. Many of our favourite foods – strawberries, coffee and cocoa – can end up shrivelled and tasteless without pollination. This ecosystem service is under increasing threat however, as pollinators face the potent cocktail of pressures we have laid upon them, declining in numbers across various parts of the world.

But what has all this got to do with international development? From what we can tell, communities in developing countries [1] are more reliant on pollinators than almost anyone, standing to lose important income, livelihoods, nutrition and cultural traditions if pollinators decline. And yet, although a number of researchers across the developing world have made substantial and important contributions to this field, limited resources and capacity have meant that only a small proportion of pollination research has focused on these regions. In fact, there isn’t even enough data to know what is happening to pollinators in the developing world, let alone how we can best conserve them and their values to human wellbeing.

Over two billion people in developing countries are reliant on smallholder farming and therefore indirectly reliant on pollinators, without necessarily knowing it. Many valuable cash crops, for example coffee, cocoa and cashews, are highly pollinator dependent and almost exclusively grown in the developing world, providing income for millions of people. In fact the reliance on pollinator-dependent crops has increased faster in the developing world than anywhere else. Reliance on beekeeping for income and livelihoods has also increased and is becoming a common component of sustainable development projects worldwide.

Worryingly, declines in pollination will have deeper consequences than just the loss of crop yields and income. Because many of the most nutritionally important food groups such as fruits, nuts and vegetables are also the most pollinator-dependent, pollinator declines are likely to shift the balance of people’s diets away from these foods. As a result, many millions of people around the world, particularly in developing countries, are expected to become deficient in important micronutrients such as vitamin A, vitamin C, iron and folate, resulting in millions of years of healthy life lost.

So what is being done about all this? In recognition of the importance of pollinators to human welfare and the threats facing them, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) commissioned a global assessment of Pollinators, Pollination and Food Production, published in 2016. This triggered a great wave of political and media attention and has resulted in the incorporation of the report’s key findings into the Convention on Biological Diversity (CBD). Many governments are now in the process of developing national pollinator strategies, including the developing nations of Brazil, Argentina, Colombia, South Africa and India. On this wave of momentum, the CBD has also requested the UN Food and Agriculture Organisation (FAO) to update their International Pollinator Initiative (IPI) which aims to build greater understanding, management and conservation of pollinators around the world. This international attention won’t last forever though, so it is important that the current momentum is sustained and built upon as soon as possible, ensuring as many countries as possible – particularly in the developing world – are involved.

The UK has a valuable opportunity to contribute to these efforts. As a centre of excellence for pollination science, it is the second largest funder and producer of pollination research after the US. But only c.6% of the £95M we have contributed to pollination research in the last 10 years has any link or collaboration with a developing country (ÜberResearch 2018). As more of the UK’s Official Development Assistance budget is made available for research, there is a shift in emphasis towards research that directly contributes towards international development. New funding programmes are encouraging the UK research community to engage in collaborative projects with researchers in developing countries, building valuable research capacity. With the relevance of pollination and agro-ecology to addressing the UN’s Sustainable Development Goals, these topics may fit into this new funding landscape. However, to be effective and ethical, partners and institutions in developing countries must be involved in the design of, and stand to benefit from these collaborations. See here for a UKCDS report outlining the ways in which academics and funders can help ensure fair partnerships.

As populations in the developing world expand, along with per-capita food demands, these issues become all the more pressing. Food production will need to increase by 70% come 2050 and this cannot be achieved by simply expanding agricultural land or fertilizer input. To ensure people are well-fed, in a way that is sustainable and ethical, we will have to intensify our farming in new ways. Understanding and managing pollination may be an important part of this and is something that researchers, politicians, agriculturalists and development workers will need to engage with sooner rather than later.

[1] For simplicity, we use the term ‘developing countries’ to refer to all countries listed in the Organisation for Economic Co-operation and Development’s (OECD) Development Assistant Committee (DAC) list of Official Development Assistance (ODA) recipients. This includes countries from a range of economic classifications, from ‘Least Developed’ to ‘Upper Middle Income’ which includes the nations of China and Brazil. Whilst we group all these nations under the broad term of ‘developing country’, we acknowledge the great heterogeneity between them in terms of wealth, development and research capacity.

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This blog has been kindly reposted from the UK CDS website. It is written by Cabot Institute member Thomas Timberlake, a pollination ecology PhD researcher from the University of Bristol who undertook a three month project with the UKCDS looking at the relevance of pollination to international development.

Thomas Timberlake

To find out more about this project you can view the full report, or watch a recording of the UKCDS Pollination and International Development Webinar.

You can also listen to Tom speaking on Nature Xposed, a University of Bristol nature radio station, about the importance of pollinators in developing countries.

If you have any comments about this blog do tweet us @cabotinstitute @UKCDS.

Reframing ecological thinking; Felix Guattari, subjectivity and film

Posted on August 25, 2017April 5, 2023 by janet.crompton

This short article introduces the ecological thought of Felix Guattari. I suggest that Guattari’s holistic delineation of three interconnected ecologies is a productive place to begin in thinking about contemporary ecological issues. Following on from this, and away from traditional environmental discourse and politics, I argue that aesthetic encounters with film hold the potential for a re-invigoration of ecological thought. I explore this briefly in relation to ‘Melancholia’ by Lars Von Trier.

The 21st Century is increasingly defined by ecological crisis. With global biodiversity losses, the rapid melting of ice-caps and glaciers, rising ocean temperatures and desertification (all complemented by humanity’s continued, unshakeable appetite for fossil fuels), the contemporary environmental moment is an urgent dilemma.

In response, academia has converged on a neologism – ‘the Anthropocene’ – as a suitable expression of contemporary ecological crisis. This is not just a geological transition; it is also an existential one. As leading geologist Jan Zalasiewicz suggests: “The significance of the Anthropocene is that is sets a different trajectory for the Earth system, of which we of course are part”[1].

The destination of this “trajectory”, with humanity in the driving seat, is currently an indeterminate futurity. Such uncertainty (which unfortunately encourages, at best, a passivity, and worse, active climate change denial), should not detract from the new reality that the Anthropocene delineates, a reality that is making itself felt in collective consciousness. Anthropocenic anxiety is spreading across all domains, not least the cultural sphere.

Screenshot from Melancholia (Von Trier 2011)

Experimental cinema, for instance, reflects and explores the particularities of the contemporary moment, almost a bellwether medium for the Anthropocene. The event of apocalypse is a prominent theme (The Day after Tomorrow (2004), Melancholia (2011)), as is what the future holds post-apocalypse (Children of Men (2006), Snowpiercer (2013), Avatar (2009), Mad Max: Fury Road (2015)). Other films engage ecological issues without the end-game of apocalypse (The Tree of Life (2011), Okja (2017), Uncertain (2017), Uncle Boonmee who can recall his past lives (2010)).

Importantly, many of these films challenge narratives of human exceptionalism, breaking-down nature-culture, subject-object binaries in the process. They problematise our dominant ways of seeing and being in the world, exposing us to a more entangled human-nonhuman milieu.

My dissertation looks to use film as the springboard for an exploration of Felix Guattari’s ecological thought. Guattari is more widely known for his collaborations with Gilles Deleuze, notably Anti-Oedipus and A Thousand Plateaus. Towards the end of his career, however, Guattari wrote two ecological texts (The Three Ecologies and Chaosmosis), reflecting a holistic concern for global environmental issues alongside molecular issues of subjectivity. In The Three Ecologies, Guattari presents a tangled ecological vision, emphasising that ecology must be rethought of in terms of three interconnected networks (mental ecology, social ecology and environmental ecology). This is Guattari’s central ecological intervention, placing environmental problems (climate change, global warming etc.) on the same plane as subjective issues and social relations. As JD Dewsbury suggests:

“Thinking with Guattari requires that we affirm and reinvigorate our experimental care for mental and social ecologies, as much as we assume a care for the state of the physical ecology of our natural environment.”[2]

Whilst climatic interventions remain important, they must be one single strand of a larger restructuring process that simultaneously includes interventions into the domain of mental ecology, a domain that, counter-intuitively perhaps, is the central focus for Guattari’s ecosophy. It might seem like a waste of time, in light of pressing environmental issues, to suddenly care so much about human subjectivity. However, as Guattari argued, it is unlikely, given our current ways of thinking and feeling about the world, that widespread economic, political or social restructuring is going to: a) be sufficient enough, or b) happen at all. Indeed, this sentiment resonates all the more strongly considering the recent failure of the Paris climate agreement.

The underlying reality, one that Guattari himself was acutely aware of, is that ecological action will remain impotent whilst it continues to be located within the far-reaching logics of capitalism and consumerism. The seeds of change, away from capitalist logics, must be planted at the molecular scale for there to be hope of molar transformation. Ecosophy has molecular transformation as its central problematic.

How, then, to change people’s subjectivities? How to encourage greater care and responsibility for all planetary life? How to problematise existing human relations, and then transform them for the better? These are big questions, with no obvious answer. However, Guattari placed great importance in what he called ‘incorporeal species’ (music, the arts, cinema), and their ability to reframe sensual perception, forcing people into encounters with alterity and nonhuman forces, perhaps engendering new modes of being in the world.

Screenshot from The Tree of Life (Malick 2011)

My dissertation looks to explore the aesthetic encounter of film. In watching films, as Guattari suggests, we “suspend the usual modes of communication for a while”.[3] This suspension, rather than being reductive, actually opens us up to processes of transformation. Film, in this way, is an encounter with forces and flows – some of them impacting before conscious recognition – a unique audio-visual assemblage that is more than just a representation of real life. In fact, films have an autonomous potential to do something in the world. I hope to explore this productivity in relation to ecosophy. What does an ecosophic aesthetics, within film, look like?

Whilst multiple films come to mind, Lars Von Trier’s critically-acclaimed Melancholia is a good place to start. The title derives from the film’s pervasion by two encircling melancholias: 1. the melancholic mental-state of central protagonist, Justine, whose struggles with depression ebb and flow throughout, and 2. the impending doom of the approaching blue
planet Melancholia, whose apocalyptic collision with Earth occurs in a prologue before we shift back in time to before the event.

Melancholia is by no means a normal ecological film; certainly, it does not follow conventional ecological film narratives. Whilst apocalypse in other films is either a future to be prevented, or a new reality that needs to be overcome, apocalypse in Melancholia is neither. There are no miraculous attempts to save humanity through science or invention. Neither is there a future after the planetary collision. The end is an end to all life, with the whole Earth dissolving into the vastness of Melancholia.

By bookending the film with apocalypse, Von Trier ensures a melancholic atmosphere throughout. This might seem like a pessimistic experience. If we analyse Melancholia in terms of its narrative, looking for conventional meanings and understandings, then certainly you might come to that conclusion. However, I believe the film can be framed in ecologically productive terms. The brilliance of Melancholia is that it strips away conventional ecological narratives throughout, particularly narratives that suggest that humanity is in any way separate from ‘nature.’

As political theorist William Connolly writes:

“Melancholia tracks beauty and ugliness, intentions and frustrations, glowing surfaces and opaque depths, regular rituals and uncanny events, entanglements and denials.”[4]

Themes of depression, capitalism, passivity and (anti)modernity weave in and out. Alongside these themes are Von Trier’s experimental filmic techniques – including an incredibly striking opening montage of 16 slow-motion tableaux vivant with Wagner’s Prelude to Tristan and Isolde in the background (a piece of music that repeats over and over in the film). Evocative visual tableaux are repeated throughout. However, in contrast, much of the rest of the film follows Von Trier’s Dogme 95 conventions: a fast-moving, continually re-focusing, handheld camera catapulting us into the midst of strained social relations. The effect, I suggest, is a scrambling of perception, with the contrasting styles leaving the audience in a continual state of disorientation. It is this disorientation that becomes a point of bifurcation, a glimmer of potential for subjective transformation.

Screenshot from Uncle Boonmee who can recall his past lives (Apichatpong 2010)

In our scenes, the film dramatises our often-ignored entanglements with nonhuman beings, our infinite connections and attachments to the world. Encountering the film, I argue, re-immerses us into the uncertainties and vulnerabilities of life in a way that other films fail to do. Maintaining a melancholic aesthetic throughout, this atmosphere soaks into the pores of the audience, forcing a confrontation with the potentially-infinite nothingness of apocalypse. Moreover, we begin to question contemporary subjective positions. If apocalypse is actually going to happen, then what is the most appropriate, or ethical, subjective response?

Space limits answering this question, and further discussion. However, I hope to use my dissertation as a more thorough exposition of these important themes and questions.

Blog by Theo Parker

Reposted from ‘Bristol Society and Space‘ Blog of the University of Bristol’s MSc in Human Geography

[1]
https://www.theguardian.com/environment/2016/aug/29/declare-anthropocene-epoch-experts-urge-geological-congress-human-impact-earth
[2] Dewsbury, JD. (2015). “Guattari’s resingularisation of existence: pooling uncertainties,” Dialogues in Human Geography,Vol. 5(2), pp. 155-161.
[3] Guattari, F. (2009). Chaosophy: Texts and Interviews 1972-1977. Los Angeles: Semiotext(e).
[4] William Connolly (2014). Melancholia and Us. Ozone.

Model uncertainties in multispecies ecological models

Posted on February 8, 2017April 5, 2023 by janet.crompton

We live in an increasingly uncertain world. Therefore, when we model environmental processes of interest, it is vital to account for the inherent uncertainties in our analyses and ensure that this information is communicated to relevant parties. Whilst the use of complex statistical models to estimate quantities of interest is becoming increasingly common in environmental sciences, one aspect of uncertainty that is frequently overlooked is that of model uncertainty. Much of the research I conduct considers this additional aspect of uncertainty quantification; that is not just uncertainty in the quantities of interest, but also in the models that we use to estimate them.

An example of this is in a paper recently published in Ecology and Evolution (Swallow et al., 2016), which looks at how different species of birds that we commonly see in our gardens respond to the same environmental factors (or covariates). Some of the species have declined rapidly over the past 40 years, whilst others have remained stable or even increased in number. Possible drivers of these changes that have been suggested include increases in predators, changes in climate and availability of natural food sources. Statistically speaking, we try to understand and quantify changes in observed numbers of birds by relating them to changes in measured environmental quantities that the birds will be subjected to, such as numbers of predators, weather variables, habitat quality etc. Most previous analyses have modelled each of the species observed at many different geographical locations (or monitoring sites) independently of each other, and estimated the quantities of interest completely separately, despite the fact that all these species share the same environment and are subject to the same external influences. So how do we go about accounting for the fact that similar species may share similar population drivers?

This essentially constitutes a model uncertainty problem – that is, which parameters should be shared across which species in our statistical model and which parameters should be distinct?

If we were to consider two different species and use two different environmental factors to explain changes in those species, say habitat type and average monthly temperature, there are four possible models to consider. That is,

Model	Habitat type	Temperature	No parameters
1	Shared	Shared	2
2	Distinct	Shared	3
3	Shared	Distinct	3
4	Distinct	Distinct	4

This can easily be extended to a higher number of species and covariates.

There is also inevitably going to be some aspects of variability shown by some of the species that we cannot account for through the quantities we have measured. We account for this using site-specific random effects, which explain variability that is linked to a specific monitoring site, but which is not accounted for by the environmental covariates in the model. Again, we would usually assume this is a single quantity representing the discrepancy between what we have accounted for using our measured covariates and what is ‘left over’. Following on from work of previous authors (Lahoz-Monfort et al., 2011), we again split this unexplained variation into two – unexplained variation that is common to all species and unexplained variation that is specific to a single species. The ratio of these two quantities can give us a good idea of what measurements we may be missing. Is it additional environmental factors that are wide-ranging in their effects or is it something relating to the specific ecology of an individual species?

In the paper, we apply our method to a large dataset spanning nearly 40 years, collected as part of the British Trust for Ornithology’s Garden Bird Feeding Survey. We selected two groups of similar species commonly found in UK gardens during the winter. For ecological reasons, we would expect the species within the two groups to show similar traits, so they act as ideal study species for detecting synchrony in responses to environmental factors. Whilst most the results were consistent with those from single-species models (e.g. Swallow et al., 2015), studying the species at an ecosystem level also highlighted some additional relationships that it would be impossible to study under more simplistic models. The results highlight that there is unsurprisingly a large degree of synchrony across many of these species, and that they share many of the traits and drivers of population change. The synchronies observed in the results corresponded to both significant positive or negative relationships with covariates, as well as those species that collectively show no strong relationship with a given environmental factor. There is, however, more to the story and some of the species showed strong differences in how they respond to external factors. Highlighting these differences may offer important information on how best to halt or reverse population declines.

The results from our analyses showed the importance of considering model uncertainty in statistical analyses of this type, and that by incorporating relevant uncertainties, we can improve our understanding of the environmental processes of interest. Incorporating more data into the analysis will help in further constraining common or shared parameters and reduce uncertainties in them. It also allows us to guide and improve future data collection procedures if we can gain a better understanding of what is currently missing from our model.

Blog written by Dr Ben Swallow, a Postdoctoral Research Associate, studying Ecological and environmental statistics in the School of Chemistry.

References

Lahoz-Monfort, J. J., Morgan, B. J. T., Harris, M. P., Wanless, S., & Freeman, S. N. (2011). A capture-recapture model for exploring multi-species synchrony in survival. Methods in Ecology and Evolution, 2(1), 116–124.

Swallow, B., Buckland, S. T., King, R. and Toms, M. P. (2015). Bayesian hierarchical modelling of continuous non-negative longitudinal data with a spike at zero: An application to a study of birds visiting gardens in winter. Biometrical Journal, 58(2), 357–371

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Figure 1. Blue tits show a highly synchronous response with great tits, and to a lesser degree coal tits, to their surrounding environment.

Figure 2. Male house sparrow feeding on fat balls. Whilst they show some synchrony in their response to environmental factors, they appear to be subject to a differing ecology to the other two species they were compared with.