Tag Archives: Nature conservation

Bird pollination finally confirmed in Britain!

In my book Birds & Flowers, I included a chapter called “The curious case of Europe”. The point of that chapter was simple enough: compared with much of the rest of the world, Europe appears to be oddly deficient in bird pollination. There are no hummingbirds, no sunbirds, no honeyeaters, and very few native plants that obviously look as though they have evolved with birds as their main pollinators. And it Britain, it appears that bird pollination is totally absent.

But “appears” is doing a lot of work there.

For decades, European bird–flower interactions have tended to be treated as marginal curiosities: Blue Tits taking nectar from willow catkins, warblers dusted with pollen, finches messing about in blossom. Interesting natural history, certainly, but not necessarily pollination. The assumption has usually been that insects do the serious work, and birds are at best incidental visitors.

A new paper in Journal of Ecology called “Generalist passerine birds perform a functional role as pollinators in temperate Europe“, by Sandra Anderson, George Perry and Rose Thorogood challenges that assumption in a very useful way. Working at Wicken Fen in Cambridgeshire, they found that pollen transport by passerine birds was widespread. Most of the birds they sampled carried pollen, and several species — including Blue Tit, Blackcap, Chiffchaff, Wren, Redpoll and Bullfinch — regularly carried meaningful loads.

More importantly, they tested whether this mattered to the plants. By excluding birds from flowers while allowing insects access, they showed that fruit-set was reduced in several early-flowering woody plants, including Blackthorn (Prunus spinosa), Hawthorn (Crataegus monogyna) and Buckthorn (Rhamnus cathartica). In other words, the birds were not just getting dusty faces. They were contributing to plant reproduction.

I should say that I was one of the reviewers of this paper, so I have followed its development with particular interest. What I like about it is that it does not try to claim that Europe secretly has a hidden flora of classic “bird flowers”. These are not red tubular blossoms adapted to hummingbirds or sunbirds. They are familiar, open, pale, spring-flowering shrubs and trees. Nor are the birds specialised nectar-feeders. They are generalist passerines making use of seasonal resources.

That is precisely why the paper is interesting. It shifts the question from “does this look like bird pollination?” to “does bird visitation actually function as pollination?” That distinction matters. Pollination syndromes can be useful, but they can also blind us to interactions that do not fit the textbook categories.

The seasonal context is also important. These interactions peak early in spring, when willows, blackthorn and other woody plants are flowering, temperatures are still cool, insects may be unreliable, and birds are preparing to breed or arriving from migration. Under those conditions, even occasional bird visits could be valuable to plants needing pollen moved between individuals.

For me, this paper strengthens the argument I made in “The curious case of Europe”: Europe is not devoid of bird–flower interactions; rather, we have been looking for the wrong kind of bird pollination. Instead of obvious “ornithophilous” specialisation, we may have overlooked a more diffuse, opportunistic, generalist system involving common birds and common spring-flowering woody plants.

That may not be as spectacular as a hummingbird hovering at a tropical flower, but ecologically it is just as revealing.

The photo above is from Birds & Flowers and shows pollen on the face of a Eurasian Blue Tit in the early spring. Bird mist-netted under licence in Northamptonshire, UK. (© Lynne Barnett)

Press release: Europe risks a crisis if it fails to halt pollinator loss, researchers warn

When an old experiment revealed a new story about flowers

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Sometimes, science does not go the way you plan.

That is usually framed as failure: the experiment did not work, the results were inconclusive, the story was unclear. But science can also advance when we go back to old data and ask a different question. That is exactly what happened with a study of Field Scabious, Knautia arvensis, a familiar wildflower of meadows and grasslands.

Back in 2001, I carried out an experiment to test the function of the showy outer florets around the edge of the flower head. These enlarged “ray florets” look as though they ought to be important in attracting pollinators. The idea was simple: trim them in different ways and see whether pollinating insects responded – you can see the results of that trimming in the photo above.

The answer, at the time, was baffling. Bumblebees, hoverflies and butterflies (all of which are effective pollinators of this plant) did not seem to care very much. Visitation rates by the insects hardly changed, and neither did seed set. But seed weight did change, as did the amount of sugar being produced by the trimmed flower heads. At the time I could not make sense of this in relation to the question I had asked, so the data were archived and left alone.

But not forgotten.

Fast forward 25 years, and I was chatting about this data set with colleagues when I was at the Kunming Institute of Botany in China. That got me reading some more recent work about florivory -the damage done to flowers by animals – and I realised that this old experiment might make more sense if viewed from another angle. Perhaps I had not really been testing floral attraction at all. Perhaps, without intending to, I had carried out a simulated florivory experiment.

Seen in that light, the results became much more interesting.

Cutting the ray florets did not stop pollinators from visiting. Nor did it reduce the number of seeds produced. But it did change the plant’s internal economics. Nectar quality declined in the most heavily cut flowers, and the seeds that those flower heads produced were consistently lighter. In other words, the flowers still functioned well enough to get pollinated, but the plant appeared to invest less in rewards for pollinators and less in each of its offspring.

That matters because lighter seeds may have poorer prospects later in life, even if the plant initially appears to reproduce successfully. The damage did not cause total reproductive failure. Instead, it produced a subtler effect: hidden costs that only become visible when you look beyond simple seed counts.

Newly contexualised in this way, we wrote up this work, being completely honest about the history of the study, submitted it to the Journal of Pollination Ecology, where it received very positive reviews. It’s now been published and you can download a copy by following the link in the reference:

Ollerton, J., Xu, X. & Ren, Z.-X. (2026) Misconceived experiments may yield valuable insights: simulated florivory has unpredictable consequences for plant reproduction in Knautia arvensis (Caprifoliaceae). Journal of Pollination Ecology (in press)

I like this study because it tells two stories at once. One is ecological: florivory may not always reduce pollinator visits, but it can still alter plant reproduction in potentially important ways. The other is about how science actually works. Not every good paper begins with a perfect hypothesis and a clean result. Sometimes the value lies in returning to an awkward, neglected dataset and realising that it was trying to tell you something different all along.

Science does not always go the way you plan. But occasionally that is when it becomes most revealing.

What the COVID lockdowns taught us about plant-pollinator specialisation in gardens

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One of the few positive things to come out of the COVID lockdowns was the unexpected opportunity to look much more closely at the nature right outside our doors. In 2020 I coordinated the Lockdown Gardens initiative, bringing together pollination ecologists from around the world to carry out standardised surveys of flower visitors in the gardens they could access during that strange and constrained period. That project generated an unusually rich global dataset: 67 gardens, almost 47,000 flower visits, and records from more than 650 pollinator species.

Since then, the dataset has started to yield some really interesting insights. A new paper led by Luis Perugini uses the Lockdown Gardens data to ask a deceptively simple question: what determines how specialised plant–pollinator interactions are in gardens? In other words, are garden flowers in some places visited by a narrow set of pollinators, while elsewhere they are more generalist?

The answers are not quite what we expected. Looking at 40 garden networks from four continents, we found that larger gardens support more plant species, and that suburban gardens tended to be richer in plant species than either rural or urban gardens. We also found that pollinator richness increased with plant richness and with precipitation. But when it came to the actual specialisation of interactions, climate and species richness did not seem to matter very much at all. Instead, variation in specialisation was mostly species-specific and showed no clear phylogenetic pattern.

That’s an important result, because it suggests that the factors that drive biodiversity in gardens are not necessarily the same factors that shape the ecological relationships within those gardens. Put more simply: having more species does not automatically mean having more specialised interactions.

For me, this is a nice example of how a project born out of a global crisis can continue to produce useful science. The Lockdown Gardens surveys began as an improvised response to an extraordinary moment, but the data are now helping us to understand how gardens function as ecological systems, and how they might better support pollinators in an increasingly human-dominated world.

Here’s the full reference with a link to the paper, which is open access:

Perugini, L., Rech, A., Ollerton, J. & Jorge, L. (2026) Global drivers of plant-pollinator interaction specialization in gardens. Ecology and Evolution (in press)

Edible Apocynaceae: a new global synthesis of diversity, conservation and pollination just published – and a personal landmark for me!

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This year – 2026 – marks the 40th anniversary of my first publication. Forty years. Imagine that – I certainly can’t! It feels like a long time ago, a distant memory, another life. I was 21 and I hadn’t even begun my undergraduate degree. After a less-than-successful time at school I decided to complete a Higher National Diploma (HND) qualification in Applied Biology at Sunderland Polytechnic (now the University of Sunderland) that I hoped would get me a place on a degree course. As it turned out, it did, but during my HND I completed a research project which (with the encouragement of my then supervisor, the late cactus expert Geoff Swales*), was subsequently published in December 1986 as “Adaptation to arid environments in the Asclepiadaceae” in the British Cactus and Succulent Journal.

That was the modest start of a botanical love affair with asclepiads (now subsumed into the family Apocynaceae) that has persisted to this day and resulted in over 20 research papers, chapters, and more general articles, plus appearances in both of my books.

The latest of these papers is published today and, as well as being a 40 year milestone for me, it’s a paper that I am inordinately proud of, as it represents an amazing coalescence of ethnobotany, taxonomy, conservation, biogeography, cultural science, and pollination ecology. And I managed to sneak in a citation of the 1986 paper that started the whole thing!

This paper is the first global review of the diversity of edible species in a family that is usually considered to be highly toxic and produces a lot of sticky latex to deter herbivores. Yet that reputation turns out to be only part of the story. Our survey found no fewer than 440 edible species of Apocynaceae worldwide, which works out at about 7.7% of the family (and is definitely an under-estimate). They occur across all of the major evolutionary lineages of the family, and in most of the main biogeographic regions where these plants grow.

What people eat is also far more varied than you might expect. Fruits are the commonest edible part, but roots and tubers are also important, and in different places people consume leaves, stems, flowers, nectar, latex, bark and even wood ash used as a condiment. That diversity is not random: our analyses show clear phylogenetic and geographic patterning in which parts are eaten. In other words, both evolutionary history and regional cultural practices help to shape how Apocynaceae are used as food.

One especially interesting result is that edible Apocynaceae appear, on current evidence, to be less threatened than non-edible members of the family. But that comes with a big health warning: more than 80% of species, edible or otherwise, have never been properly assessed for conservation status. So there is still a huge amount that we do not know.

The same is true for pollination. Many of these plants depend on animal pollinators to produce the fruits and seeds that people eat, yet pollination data are missing for most edible species, including about 90% of those whose edible parts are directly pollinator-dependent.

For me, that is one of the most striking messages of the paper. Hidden inside a family best known for poisons and medicinal compounds is a substantial, globally distributed food resource, much of it tied to local knowledge and wild harvesting. It is a reminder that botanical and cultural diversity, conservation, and pollination ecology are all bound up together. And, as a nice bonus, the study even uncovered an unexpected taxonomic surprise in China, where one edible species turned out to belong in an entirely new genus, Kushengia. The edible flowers of Kushengia sinensis are shown in the image at the top of this post – lightly boiled, stir fried with garlic, and thoroughly delicious!

Here’s the reference with a link to the paper, which is unfortunately pay-walled. If anyone wants a copy, send me a request via my Contact page:

Ollerton, J., Albuquerque-Lima, S., Liede-Schumann, S., Galetto, L., Endress, M.E., Forster, P.I., Torres, C., Fishbein, M. & Ren, Z.X. (2026) Edible Apocynaceae: phylogeny, biogeography, conservation and pollination insights from a global synthesis. Taxon 75: e70131

*It goes without saying that I’m incredibly grateful to Geoff and the other teachers and supervisors who, during the course of my education, encouraged me in my studies. During one lab session with Geoff we were each given a cactus seed and asked to study it under a microscope and draw it. Afterwards I pocketed the seed, took it home, and germinated it. That cactus – a specimen of Parodia (Notocactus) mammulosus – is still growing on my windowsill, a living reminder of a great mentor.

Connecting soils and pollinators: the ProPollSoil project kicks off in Germany!

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The ProPollSoil project officially got underway on 1st October, and this week (16th–20th November) our consortium gathered in Freising, Germany, for the kick-off meeting hosted by the Technical University of Munich. It was an inspiring start: dozens of experts from across Europe coming together to explore two big questions: How does the health of our soils shape the fate of pollinators? And how do pollinators influence soil health?

Most people think of pollination as something that happens in the air or on flowers, but for many species the story begins underground. Thousands of bees, hoverflies, beetles and wasps depend on soil to nest, overwinter, or complete parts of their life cycle. For example, around half of the solitary bee species in Britain and Ireland are what we term “ground nesting” and make their nests in different types of soil. Yet soil conditions—structure, temperature, contaminants, farming practices—are changing rapidly. As part of the EU’s Mission Soil programme, ProPollSoil aims to understand these hidden links so we can better protect the pollinators that support our food systems and ecosystems.

The project brings together specialists in entomology, soil science, ecology, modelling, agriculture, economics, and communication, forming a truly interdisciplinary team. Through desk-based reviews, fieldwork, lab experiments, monitoring and advanced modelling techniques, we’ll be investigating how soil influences pollinator survival and what we can do to improve it.

ProPollSoil is built around six key goals, including identifying the soil conditions that help pollinators thrive, testing innovative ways to monitor soil-dependent species, evaluating how different land-use and farming practices affect pollinators, and developing practical soil-management solutions—from reduced tillage to cleaner soils—that can slow or reverse their decline.

My own role mainly focuses on understanding the state of our current knowledge of the biology and ecology of soil-dependent pollinators and their interactions with soils, other invertebrates, and plants. I’ll also be working on integrating information about pollinators’ soil dependencies into the European Atlas of Plant-Pollinator Associations (EuroAPPA), part of the related Butterfly Project, whose kick-off meeting I documented on the blog earlier this year.

Together, these efforts will help build a clearer, more complete understanding of how life belowground supports life aboveground. It’s an exciting journey, and we’re only just getting started!

My sincere thanks to all of the ProPollSoil consortium members whose passion and expertise made for a stimulating few days in Germany. And a special shout-out for the team from Poland who brought with them some delicious, PropPollSoil branded sweets:

Book review: “Urban Plants” by Trevor Dines

Pollinators need more space and 10% habitat is not enough says a new study just published in Science

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Pollinators such as wild bees, butterflies, and hoverflies are in trouble worldwide. A major new study, published in Science and led by Gabriella Bishop and other scientists at Wageningen University & Research, shows that the oft-quoted figure of 10% semi-natural habitat in farmland landscapes is far too little to safeguard pollinators. Instead, the evidence points to a need for somewhere between 16% and 37% habitat cover, depending on the type of pollinator, if we are serious about halting declines. Suitable habitats include hedgerows, patches of woodland, species-rich grasslands, and flowering margins, and as a general rule, hoverflies need less of it whilst bumblebees and butterflies require more.

I was fortunate to play a part in this global assessment, contributing an unpublished dataset collected with my former PhD student, Sam Tarrant, who studied plant-pollinator interactions on restored landfill and established grassland sites. Seeing those data joined with dozens of other studies from around the world underlines something we have known for years: no single dataset, however carefully gathered, can give us the whole picture. To really understand what is happening to biodiversity—and to design conservation solutions that work—we need these kinds of global, mega-author syntheses that draw together evidence from many landscapes, taxa, and approaches.

The message from this analysis is stark but hopeful. More habitat means more pollinators, across all groups. Richer habitats with abundant flowers give an additional boost, but the overriding priority must be to increase the sheer area of natural habitat in farmed landscapes. Small-scale fixes like wildflower strips offer short-term benefits, but without enough space they can’t deliver recovery at scale. Long-term, secure habitat creation—on the order of decades, not seasons—is what pollinators, farmers, and ecosystems need.

Although the policy debate in Europe provided the backdrop for this study, the lessons (and the data) are global. Wherever agriculture dominates, the health of pollinator populations—and by extension our food security and biodiversity—depends on our willingness to give these insects the space and quality of habitat they require.

Looking ahead, we need to think bigger and work together. That means more international collaborations, more sharing of data, and more commitment to long-term solutions that transcend borders. The image at the start of this post is from my trip back to China in July this year. I deliberately chose it because, as you’ll see from the map below which is taken from the paper, there was no suitable data available for the study from that country. Or from Africa. Or Australasia. Or from most of tropical South America. That shows that as pollination ecologists we need to coordinate more in advance on these types of syntheses, and maximise the value of the kinds of data that we collect. The main take away from this study, however, is that if we want to reverse the declines in biodiversity, scientists, policymakers, businesses, farmers, and citizens all have a role to play. Pollinators remind us that nature is interconnected and global—our conservation efforts must be, too.

Here’s the full reference with a link to the study:

Bishop, G.A., Kleijn, D., Albrecht, M., Bartomeus, I., Isaacs, R., Kremen, C., Magrach, A., Ponisio, L.C., Potts, S.G., Scheper, J., Smith, H.G., Tscharntke, T., Albrecht, J., Badenhausser, I., Åström, J., Báldi, A., Basu, P., Berggren, N., Beyer, N., Blüthgen, R., Bommarco, B.J., Brosi, H., Cohen, L.J., Cole, K.R., Denning, M., Devoto, J., Ekroos, F., Fornoff, B.L., Foster, M.A.K., Gillespie, J.L., Gonzalez-Andujar, J.P., González-Varo, J.P., Goulson, D., Grass, I., Hass, A.L., Herrera, J.M., Holzschuh, A., Hopfenmüller, S., Izquierdo, J., Jauker, B., Kallioniemi, E.P., Kirsch, F., Klein, A.-M., Kovács-Hostyánszki, A., Krauss, J., Krimmer, E., Kunin, B., Laha, S.A.M., Lindström, Y., Mandelik, G., Marcacci, D.I., McCracken, M., Monasterolo, L.A., Morandin, J., Morrison, S., Mudri Stojnic, J., Ollerton, J., Persson, A.S., Phillips, B.B., Piko, J.I., Power, E.F., Quinlan, G.M., Rundlöf, M., Raderschall, C.A., Riggi, L.G.A., Roberts, S.P.M., Roth, T., Senapathi, D., Stanley, D.A., Steffan-Dewenter, I., Stout, J.C., Sutter, L., Tanis, M.F., Tarrant, S., van Kolfschoten, L., Vanbergen, A.J., Vilà, M., von Königslöw, V., Vujic, A., WallisDeVries, M.F., Wen, A., Westphal, C., Wickens, J.B., Wickens, V.J., Wilkinson, N.I., Wood, T.J., Fijen, T.P.M. (2025) Critical habitat thresholds for effective pollinator conservation in agricultural landscapes. Science 389: 1314-1319

Here’s the abstract:

Biodiversity in human-dominated landscapes is declining, but evidence-based conservation targets to guide international policies for such landscapes are lacking. We present a framework for informing habitat conservation policies based on the enhancement of habitat quantity and quality and define thresholds of habitat quantity at which it becomes effective to also prioritize habitat quality. We applied this framework to insect pollinators, an important part 5 of agroecosystem biodiversity, by synthesizing 59 studies from 19 countries. Given low habitat quality, hoverflies had the lowest threshold at 6% semi-natural habitat cover, followed by solitary bees (16%), bumble bees (18%), and butterflies (37%). These figures represent minimum habitat thresholds in agricultural landscapes, but when habitat quantity is restricted, marked increases in quality are required to reach similar outcomes.

Book review: ‘The Dales Slipper: Past-Present’ by Paul Redshaw

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Tomorrow I head to China for two months of writing, field work, talks, and student discussions at the Kunming Institute of Botany in China, a follow-up to the work that I did last year. It feels appropriate, therefore, to be reviewing a book devoted to a western European outlier of a group of orchids (the ‘lady’s slippers’) that have one of their centers of diversity in that country.

In The Dales Slipper: Past-Present, author Paul Redshaw focuses on ‘the’ Lady’s Slipper (Cypripedium calceolus), an almost mythological species in British botany, due to its extreme rarity, the secrecy and protectiveness about where it grows, and its tendency to be dug up by unscrupulous orchid collectors. And a fascinating (if sometimes frustrating) read it is too!

The fascination of the book lies with Paul’s ability to sleuth previously unknown facts from local people who were witnesses to the rediscovery and subsequent protection of what was thought to be the last colony of the species in Britain. Protection was afforded by ‘The Guardians’ who (of course) met in a pub and were sworn to secrecy and (of course) fell out when personalities and priorities clashed. They were replaced (ousted?) by a more formal ‘Cypripedium Committee’ that still exists today, but who (if the author is to be believed) are even more secretive than The Guardians!

Drawing on newly uncovered archives, personal testimonies, and previously unseen images, the book details the decades-long efforts – marked by secrecy, dedication, and conflict – to protect the species from extinction. It stands as the first comprehensive and fully referenced account of this remarkable conservation journey

It makes a compelling story of the kind I can imagine being a successful comedy-drama for television – think Detectorists with hand lenses.

I mentioned that the book was a frustrating read, too. That’s partly because there’s a big cast of characters, some of whom have the same names, and it’s easy to lose track of who they are and what they did, and when. Paul does provide a helpful list of the protagonists but I found myself feeling a bit lost in places. That’s not helped by the fact that the book would have benefited from professional editing to smooth the rough edges.

These minor gripes aside, The Dales Slipper will interest anyone looking for a deep dive into British botanical history via the world of one of our rarest and most iconic wild plants.

A new study examines why data quality matters in plant–pollinator databases