Category Archives: Biodiversity

Why are there large gaps in the British distribution of Common Elder?

Back in mid-April, Karin and I spent a long weekend in the New Forest, exploring the walking trails around the village of Brockenhurst and watching the bird life of the coastal wetlands near Lymington. After a few days something odd struck me: the hedgerows and woodland edges in the area contained almost no Common Elder (Sambucus nigra). Why is that odd? Well, in the article I wrote about Common Elder in 2022 for British Wildlife, I described the plant as ‘so commonplace that we hardly give it a second glance’. Common Elder is such a ubiquitous species that, as Sherlock Holmes observed in The Adventure of Silver Blaze, its absence in a landscape struck me as a ‘curious incident’.

At first I thought that I was so preoccupied with the New Forest’s birds and other wildlife and just not spotting elder, which early in the season, before it flowers, tends to merge into the general greenery of the countryside. Because elder is everywhere, right? In fact this map from the Biological Flora of the British Isles account of the species showing the occurrence of the species in 10km squares suggests just that:

Similarly, if you look at the distribution map of Sambucus nigra from the NBN Atlas, it also appears that it’s everywhere, a big blob of elderlyness across the whole country:

That’s not surprising, I can imagine you’re thinking, after all its berries are eaten by a range of birds and mammals, that disperse its seeds far and wide. It’s just the kind of species that you would expect to be widespread across the country. Which of course it is – it’s a very common species. But once you focus more closely on specific parts of Britain you see that there are some striking gaps in where elder is commonly found. Indeed one of these elder lacunae is in and around the New Forest:

So my impression was correct – the New Forest really is an elder cold spot, along with most of the Isle of Wight. Zoom back out and we see that this lacuna is part of a wider band of elder absence that extends across the southeast of England. There’s also gaps further west, in Somerset and in Devon.

It’s not just in southern England that these elder lacunae occur – look at its absence from much of Lincolnshire, for instance:

What’s going on here? Why do these gaps in the distribution of this common species occur? Part of the answer is that, being so common, Common Elder tends not to be recorded because naturalists often focus on rare and unusual species, neglecting the commoners. This form of bias is often encountered when dealing with biodiversity databases – we found it in our study of trends in diversity and abundance of Neotropical pollinators, for instance. I’m certain that this is a factor in the NBN Atlas account of Common Elder, because if we look at a part of Britain with which I am very familiar, centered on the town of Northampton, I know for a fact that elder is extremely abundant even if the map suggests otherwise:

But lack of records cannot be the only answer to these gaps: Common Elder really is not very common in the New Forest – I’ve (not) seen it with my own eyes! So what else could be going on? It doesn’t seem to relate to underlying geology or soil type, and indeed Common Elder is tolerant of a wide range of edaphic conditions: the Biological Flora account shows that it occurs on sandy, chalky and loamy soils, ranging from pH 4.2 to pH 8.7. So I wonder if the answer has a more cultural basis? Has Common Elder been actively removed from some areas in the past, perhaps because of its supernatural associations (something that I discussed in my article) or, more prosaically, because it’s believed by farmers to be toxic to stock, or just not a very good hedging plant?

As always, I’d love to hear your thoughts on this, please comment below or send me a message via my Contact page.

(Bee) Sex in the city: a new study shows how urban life skews pollinator populations

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Bees are among the most important pollinators in the natural world, quietly sustaining ecosystems and food production. While honeybees often steal the spotlight, a vast number of solitary and primitively eusocial bees play equally vital roles. But across both urban and natural landscapes, many of these species are facing worrying declines.

As cities expand, they’re increasingly being seen not just as threats to biodiversity, but as potential refuges for pollinators. Yet urban environments are very different from natural ones. The heat generated by buildings and concrete – known as the urban heat island effect – and the way green spaces are managed (often with little consideration for flowering plants) could be affecting bees in ways we’re only beginning to understand.

As part of a recent study led by my former PhD student Muzafar Sirohi, we explored how urban conditions might be influencing the timing of bee emergence and the sex ratios of different species. This work formed part of Muzafar’s PhD research, and I was pleased to be part of the team that supported and collaborated on the project.

We found that several solitary bee species were producing females before males – a reversal of the more typical pattern known as ‘protandry’, where males emerge first. Most bees in the families Apidae and Megachilidae did follow the usual male-first pattern, but there were some interesting exceptions, including Nomada marshamella and Nomada fabriciana. Soil-nesting species also showed a lot of variation in emergence timing, likely influenced by microclimatic differences in urban soils.

When we looked at overall sex ratios, patterns varied across bee families. In Halictidae, females were more common, whereas Apidae and Megachilidae were skewed towards males. Interestingly, the Colletidae family showed no strong bias either way. However, in five species from the Andrenidae and Halictidae families, we saw a clear difference between urban and natural environments: urban populations had a higher proportion of males.

This could suggest that urban habitats – especially those with limited floral resources due to mowing, paving, or the removal of wild plants – may not be supporting as many female bees. Since females are the ones responsible for nest-building and potentially pollination, as they visit more flowers, this imbalance could have long-term effects on bee populations and the pollination services they provide.

Our study adds to the growing body of evidence that urban environments can support pollinators – but only if managed thoughtfully. Cities need more than just green space: they need flowering plants, nesting habitats, and careful planning that recognises the delicate balance of bee ecology. With the right actions, we can make urban areas part of the solution to pollinator decline.

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

Sirohi, M.H., Jackson, J. & Ollerton, J. (2025) Sex ratios and sex-biased emergence of solitary and primitively eusocial bees in urban settings and nature conservation areas. Ethology Ecology & Evolution (in press)

Here’s the abstract:

Solitary and primitively eusocial bees are essential pollinators of plants. However, recent observations indicate a decline in their populations in both urban and natural environments. Urban areas are increasingly recognized as potential habitats for bee conservation. Nonetheless, these urban habitats can influence the taxonomic and functional diversity of bee populations. Therefore, we hypothesize that the distinctive warmer climate of urban areas – resulting from the urban heat island effect – along with the potential scarcity of floral resources, contributes to shifts in emergence patterns and the sex ratio of solitary and primitively eusocial bees. We found that many solitary bee species produced females before males. Additionally, most species within the Apidae family were recorded as protandrous, with the exceptions of Nomada marshamella and Nomada fabriciana. All species of Megachilidae were found to be protandrous. We also observed significant variation in the emergence patterns of soil-nesting species. Notably, we did not find any relationship between sociality and nesting preferences in relation to sex-biased emergence. The overall sex ratio varied among different bee species and families. In Halictidae family, sex ratios were biased towards females, while the Apidae and Megachilidae families exhibited a skewed ratio towards males. The sex ratio in the Colletidae family did not show any significant difference. However, among the Andrenidae and Halictidae families, we identified five species with significantly different sex ratios between urban and nature areas, with a higher proportion of males observed in urban sites. This suggests that these species may have been affected by limited food resources, potentially due to urban management practices such as the removal of floral resources. This could lead to increased competition for resources among the species.

Flowers, feathers and time: a new study of the temporal dynamics of plant-hummingbird interactions just published

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What happens when you spend an entire year watching hummingbirds and the plants they visit in one of Brazil’s most unique ecosystems? You begin to unravel the complex, ever-changing relationships that tie together birds, flowers, and the environment they share.

In a new study jointly led by Steffani Queiroz and Marsal Amorim — and part of my ongoing collaboration with a brilliant team of Brazilian hummingbird researchers — we explored how plant–pollinator interactions shift over time in the Campo Rupestre, a montane tropical ecosystem rich in biodiversity and endemic species. Despite the region’s relatively stable climate, we found that the relationships between hummingbirds and flowers are anything but static.

Over the course of 624 hours of observation spread across a full year, we recorded over 9,000 hummingbird visits involving nine bird species and 47 plant species. Many of these plants — and one of the most frequent visitors, the stunning Hyacinth Visorbearer (Augastes scutatus) — are found nowhere else on Earth.

Our goal was to understand how the structure of this ecological network — which plants interact with which hummingbirds, and how often — changes over time, and what drives those changes. Are they shaped by morphological fit (the match between beak and flower shape)? By phenology (when plants bloom)? By nectar characteristics such as the amount produced and its sugar concentration?

What we discovered is that different factors dominate in different seasons. During the rainy season, when hummingbirds are more abundant, interactions were shaped mostly by morphological matching — suggesting that competition leads to greater niche partitioning. In contrast, during the dry season, the network became sparser and was more influenced by nectar sugar content and flowering patterns.

Interestingly, while the overall annual network wasn’t especially nested (a common pattern in mutualistic networks), it was highly modular — meaning that it contained distinct clusters of species that mostly interacted among themselves. This structure changed significantly across months, highlighting the dynamic nature of tropical plant-pollinator interactions, even in environments with relatively little climate variation.

This work highlights the importance of long-term, fine-scale studies in uncovering how interactions among species shift through time. It also underscores the remarkable biodiversity and ecological complexity of the Campo Rupestre — and the need to understand and protect it.

Here’s the reference – if anyone wants a copy, drop me a message via my Contact page:

Queiroz, S.N.P., Amorim, M.D., Lopes, S.A., Vizentin-Bugoni, J., Jorge, L.R., Ollerton, J., Santos, T. & Rech, A.R. (2025) Temporal dynamics of a Neotropical plant-hummingbird interaction network. Austral Ecology 50:e70089

And here’s the full abstract:

Species interaction networks are expected to vary following temporal changes in the environment and the composition of the local community. However, there are still gaps in our knowledge about temporal variation in networks in tropical areas, where less variable climates are expected to produce more stable community structures over time. Here we describe a plant-hummingbird network in the Brazilian Campo Rupestre ecosystem and investigate multiscale temporal variation of interactions in this community as well as the possible mechanisms underlying the frequencies of species interactions. Plants visited by hummingbirds were observed monthly for a year and each species had morphology, phenology and nectar traits measured. During 624 h of observation we recorded nine hummingbird species visiting 47 plant species, amounting to 9015 visits to flowers. Most plants (28 species) were endemic to the Campo Rupestre and mostly visited by the also endemic hummingbird Augastes scutatus (the Hyacinth Visorbearer). The annual network was not nested but presented high modularity and intermediate specialisation. While the overall (annual) frequencies of interaction were primarily defined by morphological matching and phenological overlap, we found a remarkable temporal change in community structure over the year, with different processes underlying interactions among plants and hummingbirds at different seasons. The interaction pattern during the rainy season was more similar to the annual network than the dry season (when nectar sugar content and plant phenology were also important), with more links per species and lower specialisation. The higher importance of morphology to predict interactions during the rainy season suggests higher niche partitioning when more hummingbird species are present in the community. Our results exemplify the importance of considering the temporal dynamics of the community to advance the understanding of the processes defining species interactions over time in the tropics.

My sincere thanks to Sinzinando Albuquerque-Lima for the photograph, which was taken in the Amazon, not where the research described above was conducted.

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

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Imagine trying to put together a giant puzzle where each piece represents an interaction between a flower and the insect, bird, bat or other animal that helps it reproduce. In recent years, scientists have gathered millions of these “puzzle pieces” into massive online databases, offering an unprecedented view of how plants and their pollinators connect around the world.

But there’s a catch: not every entry in these databases is equally reliable. Did the researcher actually watch the insect brush pollen against the flower’s stigma? Or did they simply note that the insect visited the blossom and assume pollination happened? Without clues about how each plant–pollinator link was documented, users can’t tell solid evidence from a best guess.

That’s why a growing number of projects are now tagging every interaction with a “data quality badge”—a short note explaining the exact kind of proof behind the record. For example:

Direct observation: A scientist observed an animal pollinating a specific flower.
Pollen analysis: Pollen grains matching that flower were found on the insect’s body.
Inferred pollinator: The animal regularly visits those flowers and shares similar traits with known pollinators.

Initiatives like the Pollinators of Apocynaceae Database and the Database of Pollinator Interactions (DoPI) have already adopted these quality flags. The upcoming USDA-NRCS PLANTS database is doing the same, and Brazil’s REBIPP network has developed a standardized set of terms—rooted in the global Darwin Core standard—to make sure everyone speaks the same “pollinator language.”

Why is this important? When you know the strength of the evidence behind each plant–pollinator link, you can:

Fill in real knowledge gaps with confidence.
Identify weak spots in our understanding that need more fieldwork.
Build better conservation plans, targeting the most critical pollinators for at-risk plants.

Ultimately, adding clear data-quality labels turns these massive collections of observations into powerful tools for science, restoration, and education. And that’s good news not only for researchers, but for every garden, farm, and wild ecosystem that depends on diverse and abundant pollinator communities.

These issues are explored in a new, open-access paper written by colleagues from Brazil, the USA and myself. In the paper we discuss the importance of data quality in plant-pollinator databases and suggest methodologies for improving it. Here’s the reference with a link to the paper:

Ollerton, J., Taliga, C., Salim, J.A., Poelen, J.H., & Drucker, D.P. (2025) Incorporating measures of data quality into plant-pollinator databases. Journal of Pollination Ecology 38: 151-160

This paper is a direct output from the EU-funded WorldFAIR Project in which I was involved, though we also acknowledge the SURPASS2 project as a precursor to this. Looking ahead, we’re also going to be adopting the recommendations from our paper in the new Butterfly Project (also EU-funded). Finally, by way of a teaser, I can tell you that our new paper will also be relevant to another large project in which I’m involved, that has successfully secured funding…but you’ll have to wait until later in the year to hear about that!

Thanks to Chris Taliga for the photo.

A new study shows how garden flowers keep city pollinators flying all year round

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When we think of cities, gardens might not be the first thing that comes to mind. But these green patches — whether in private yards, parks, or balconies — play a surprisingly important role in supporting urban wildlife. Among their most crucial guests? Pollinators like bees, butterflies, and even birds and bats.

In a new study just published, I teamed up with some Brazilian colleagues to explore how the different features of garden flowers help sustain pollinators throughout the year in a subtropical urban garden. While we’ve long known that garden flowers provide food for pollinators, what’s less clear is how specific floral traits — like shape, flowering time, and type of nectar or pollen — influence who visits which plants and when.

To get a clearer picture, we conducted weekly surveys of pollinators visiting garden flowers over the course of a year. We paid close attention to traits such as the depth of flower, the kind of resources offered (nectar vs. pollen), how closely related different plants were, and when they flowered.

What we found was striking: the network of interactions between flowers and pollinators was highly organized. Plants grouped into clusters, or “modules,” that tended to share similar physical traits and evolutionary histories — but interestingly, not the same flowering times. This meant that within each module, different plants flowered at different times of year, effectively staggering their blooms so that there was always something on offer for pollinators.

Even more intriguing was the discovery that most plants had just a few connections in the network, usually restricted to a single module. These “peripheral” plants accounted for over 85% of all pollinator visits. Meanwhile, a few special species acted as bridges between modules — their role in linking different parts of the network made them key to its stability. These connector species didn’t flower at the same time, which helped to maintain a steady supply of food for pollinators across seasons.

Not all interactions between plants and pollinators are “legitimate” in the sense of leading to pollination. Some animals visit flowers just for the food, without helping with reproduction. But our study found that these interactions still played a valuable role in supporting a diverse pollinator community.

So what does all this mean for urban gardeners and city planners?

First, it highlights how important it is to plant a variety of flowers that bloom at different times of year. Second, it shows that even seemingly minor plants or interactions can contribute to the ecological resilience of urban green spaces. And finally, it underscores that thoughtful planting — considering things like flower shape, blooming schedules, and diversity — can help keep pollinators thriving, even in the heart of the city.

Urban gardens aren’t just pretty — they’re powerful allies in the fight to support biodiversity.

The study was led by Brazilian research student Luis de Sousa Perugini. Here’s the reference with a link to the paper:

de Sousa Perugini, L.G., Jorge, L.R., Ollerton, J., Milaneze‑Gutierre, M.A. & Rech, A.R. (2025) High modularity of plant-pollinator interactions in an urban garden is driven by phenological continuity and flower morphology. Urban Ecosystems 28, 126

Here’s the abstract:

Garden flowers play a vital role in urban environments, supporting pollinator communities. Yet, the extent to which floral traits shape urban pollination networks remains poorly understood. This study investigated how garden plants shape year-round pollination networks, sampled in weekly surveys in an urban subtropical garden. We focused on the role of floral morphology (corolla depth), type of resource, relatedness, and phenology in the organization of interactions. We determined whether modularity and species roles were influenced by these floral traits, comparing if legitimate pollination, illegitimate (i.e. non-pollinating) interactions and all interactions had similar drivers. All networks were modular, and in the overall network plants within the same module were morphologically and phylogenetically similar while their phenology was significantly overdispersed throughout the year. Peripheral species, those with few interactions and restricted to a single module, dominated all networks, representing over 85% of interactions. We found that phenology was related to the species role of overall network connectors (species that connect modules) and legitimate module hubs (species that connect their own modules). Both showed no overlap in their flowering periods, providing floral resources at different times of the year. Each module functioned as a distinct unit, showing year-round availability of resources to support its pollinators. This suggests that resource continuity and trait-based filtering may shape pollinator assemblages influencing ecological resilience in urban habitats. Even interactions that do not contribute to plant reproduction can sustain a diverse fauna, highlighting the importance of these interactions in urban green space planning and management.

The Black Cats go green, and go up!

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It’s impossible to be a native of Sunderland and not to have at least a passing interest in football. If you’ve seen the Netflix series Sunderland ‘Til I Die, you’ll know that in my home town, football is more of a religion than a leisure activity. It’s a passion that extends back to the foundation of Sunderland Association Football Club (SAFC) in 1879, whose nickname is the Black Cats.

Growing up, football was always a topic of discussion in our house. My dad played Sunday League football for many years and my Uncle Gordon Howe was a professional footballer. But to the general disappointment of my family, I’ve never had a deep interest in the sport, though I do keep a watch on how well the team of my birthplace is doing. And as of yesterday they are doing extremely well! The team beat Sheffield United (ironically, one of the teams that Uncle Gordon played for) in a thrilling, close-run match to earn promotion back into the Premier League. I watched it live with friends in a local pub, and there was a great reception to the win, even among customers who had no vested interest in the club.

It brought back memories of the mid-1970s when I attended matches at SAFC’s old Roker Park stadium, buoyed up by the club’s ‘giant killing’ win over Leeds United in the 1973 FA Cup Final. But even after my childhood interest in football waned, replaced by a growing fascination with natural history, home matches were frequently a backdrop to Saturdays. The famous Roker Roar always signaled that the team had scored. That shout echoed across the town and down through the Magnesian Limestone gorge of the River Wear, part of which you can see in the photograph above. Exploring the exposed geology, and the grassland and brownfield habitats of that river valley, is an important reason why I became an ecologist, as I recounted on the blog a decade ago.

The shot was taken in early 1986 and it shows the view from the back of the house in which I grew up. On the south side of the river, you can see cranes and sheds associated with the shipbuilding industry, for hundreds of years one of the two main engines of the local economy. Directly ahead, situated on a promontory, you can see an example of the second engine: Wearmouth Colliery, a 2,000 ft deep coal mine that extended out under the North Sea. The mine employed quite a number of members of my family, including my grandfather and several uncles*, one of whom was killed in the early 1900s after a pit pony kicked him. My dad was also a miner for a time but he worked further up river at the Hylton Colliery, which produced more than its fair share of professional footballers, as well as coal.

In 1993 Wearmouth Colliery closed and the site was quickly cleared – see this amazing set of photos that was taken at the time. Four years later, SAFC closed Roker Park and moved to a new purpose-built stadium on the colliery site. They called it The Stadium of Light, a name that honours the ‘miners at Wearmouth Colliery [who] carried with them a Davy lamp as part of their working lives’. Here’s a shot of the stadium perched above the river, taken by my good friend Mark:

Not only have Sunderland gone up, they have also gone green, with a commitment to be carbon neutral and generate their own power from solar installations (though that scheme has attracted some controversy). They are also making the team’s kit from recycled plastic bottles and looking at more environmentally friendly ways of dealing with match day waste – see this press release on their ‘Ready Eco’ initiative. There’s also a plan to tap into the geothermal potential of the mine to heat local houses, though that has been delayed, unless anyone has more recent news on the scheme?

Biodiversity, always the Cinderella of environmental mission statements, is missing from that initiative, which is a shame because the stadium lies adjacent to some very interesting habitats. To the left of the stadium, on the steep slopes of the gorge, you can see patches of Magnesian Limestone Grassland, a relatively rare plant community that is virtually confined to the North East of England.

This minor gripe aside, it’s great to see Sunderland being promoted and taking a lead in thinking about how football as the national sport has an environmental impact. It makes me even prouder of my home town.

*When I was researching this post I came across the following article from the local newspaper. It mentions my Uncle Walter Ollerton who earned a safety badge that is still in my possession. At the outbreak of World War 2 he enlisted and fought in the Far East, where he was captured by the Japanese and held in a prisoner of war camp. After his release he returned to his job as a miner in Sunderland, but his health was never the same:

Have we passed “peak honey bee” in Britain? An update of hive numbers for World Bee Day 2025

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Since publishing what I believe are the most comprehensive data on the number of honey bee hives in Britain in my book Pollinators & Pollination: Nature and Society, I’ve posted occasional updates on my blog as more recent data become available. I believe that the last of these was in 2022 – see Have honey bees declined in Britain? An update of the numbers – so it feels like it’s time for another. And what’s more appropriate than to post this on World Bee Day 2025?!

Rather than the complex, multi-coloured graph that I’ve produced in the past, I’ve decided to streamline the presentation and simply fit a smoothed LOESS line with a 95% confidence ribbon to the (sometimes contradictory) data points, in order to show the overall trend (see the graph above). If you compare it with the 2022 update you’ll see that the general message from the data is the same: a peak in numbers of hives in the late 1940s (which may or may not be an artefact*), then a steep decline into the 1970s and 1980s, followed by recovery from the 1990s onwards. Note that I’ve removed the two very early data points because I don’t think that they are at all accurate.

The most recent data (2015 to 2024) come from the National Bee Unit which relies on beekeepers to submit their own records, but are probably no less accurate than some of the other data that’s available! If we take a close look at that time period we see something interesting – honey bee hive numbers are decreasing:

What are we to make of this? In an analogy with peak oil, why do we seem to have passed ‘peak honey bee’? If this is a real pattern (and only time will tell) I suspect that it’s because of at least two factors. The first is that interest in beekeeping reached a peak in the early 2020s, after which some initial enthusiasts discovered that beekeeping is actually quite a technical and demanding hobby, and gave it up. The second factor is that word has spread that , globally, managed Western honey bees are not declining, and too many bee hives in an area can have negative impacts on other, wild pollinators. This may have impacted those people who were persuaded by “Save the Bee” campaigns to take up the hobby, to give up beekeeping.

There could well be other reasons that I’ve not considered and, as always, I’d be interested in your thoughts – please leave a comment below. I’ll finish by saying that I make no judgement on this. There’s no doubt that there are too many hives in some parts of Britain, especially in London, and if the trend I describe reduces the pressures on wild pollinators, that’s a good thing. At the same time, honey bees are important agricultural pollinators in some circumstances, especially where there’s mass-flowering crops that require huge numbers of pollinating bees to be available over a short time period. And I like honey as much as the next person.

Happy World Bee Day to my readers!

*There’s a long-standing suggestion that beekeepers in the post-war years inflated the number of hives that they kept in order to obtain a larger sugar ration.

‘Why Do We Need Worms?’ long-listed for the School Library Association Book Awards!

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Since early 2021 I’ve acted as a science advisor for some of the children’s books published by Usborne, beginning with Can We Really Help the Bees? The most recent is Why Do We Need Worms?, written once again by Katie Daynes and with amazing illustrations by Moesha Kellaway. I’m especially proud of my involvement with this book as in its early stages I suggested mentioning Charles Darwin’s fascination with worms. The book is aimed at ages 4 and upwards, though a reviewer has said that it’s ‘Perfect for my 3 year old grandson who loves looking at worms!’ So this book has to have one of the youngest Darwin readerships!

Why Do We Need Worms? was published last year and I’m delighted to say that this year it’s been long-listed for the School Library Association Book Awards in the 0 to 7 years Information Book category! It’s a great achievement for everyone involved and if the book gets short-listed, I will be sure to let you know.

Mindful Mow May!

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As April comes to a close, many people with gardens will be considering having a No Mow May in which, to quote Plantlife, you ‘pack away the lawnmower, let wildflowers grow freely and help nature’. On the face of it this is a positive thing and (hopefully) it gets people thinking a bit more about the impact of gardening practices on wildlife. However, I do worry that its message is too simplistic, as I’ll explain in the rest of this post. Let me say at the outset that I’m using the word ‘mindful’ in its sense of ‘paying attention to’, rather than in relation to mental health mindfulness. Though there are certainly connections between lawns and both meanings of this word, for example mindfully watching pollinators in your garden.

I’ve previously written about the garden that Karin and I developed in Northampton, including a ‘defence’ of its lawn. During the lockdown spring and summer of 2020, when I coordinated a loose consortium of scientists to collect standardised data on the flowers and pollinators in their own garden, our lawn was one of the areas that I surveyed. In that year, as every year, we had no intention of not mowing the lawn, but of mowing it in a mindful way that left some flowering patches of the main nectar sources: Dandelion (Taraxacum officinale), White Clover (Trifolium repens), and Daisy (Bellis perennis). It also allowed a patch of Common Ragwort (Jacobaea vulgaris), and the Cinnabar Moths (Tyria jacobaeae) that depend on it, to come back year after year.

In the graph below you can see the nectar production of dandelions, clovers and daisies over the course of the late spring to late summer. For each species, I have multiplied the number of flower heads I counted by the average amount of nectar sugar per flower head from the data collected by the Agriland project. Clover produces 48.97 micrograms of sugar per day, by far the highest amount of the three. Daisy produces the least, just 0.84 micrograms, and dandelion is in the middle with 22.57 micrograms.

Because these species vary in their peak flowering, there’s a continuous supply of nectar in the lawn over this time period and mowing does impact the immediate availability of nectar. Using green shading, I’ve marked the two days when I know for certain the lawn was mown and you can see that there’s an immediate drop in the nectar. Here you can also seen that both dandelions and daisies re-flower quite soon afterwards – it’s not a permanent effect by any means. The same is probably true of clover later in the season, but unfortunately I didn’t record the exact mowing dates.

The important thing to appreciate here is that without mowing, these three species would probably disappear from the lawn because all require that grasses are suppressed in order for them to flourish. Not only that, but most ground-nesting bee species need either very short turf or bare soil in which to nest. And most bees, at least in the UK, are ground-nesting.

The image at the top of this post is from my book Pollinators & Pollination: Nature and Society, and it shows two views of the same grassy, south-facing bank in Kettering, Northamptonshire. I included it because it’s a nice example of the mindful approach to lawn mowing that I am describing: bees are able to nest in the low-cut turf and collect the nectar and pollen from the flowers in the unmown areas. Later in the season that unmown area will be cut. This is referred to as ‘matrix mowing’, which is to say that by cutting some areas and leaving others, you create a matrix of different lawn lengths that has a greater overall benefit than is obtained by either cutting everything at the same time or cutting nothing for a whole month. It’s even better if you have the space to leave some patches unmown for a year or two. That way you create longer grassy areas in which insects can over winter and some bumblebees can nest.

It’s worth mentioning at this point that I know of only one published study that’s assessed the impact on No Mow May on pollinators, and that study was retracted shortly after it appeared. If I’ve missed other studies please do let me know in the comments.

I’ll finish with the Royal Horticultural Society, which was in the news recently with an announcement that it’s collaborated with gardener Monty Don to come up with ‘hard-wearing flower lawn that is good for pollinators, dogs and people’. This is hardly rocket surgery, it’s the sort of diverse, low-input, low maintenance lawn that many of us have been advocating for years, but if it brings these ideas to popular attention, so much the better.

So, consider engaging in Mindful Mow May (and April, and June, and all the other months!) As always, feel free to comment below or get in touch with me via my Contact page.

Project ‘Butterfly’ takes flight in Paris!

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At the end of last week I joined researchers from across Europe and beyond who gathered at Norway House on the campus of the Cité Internationale Universitaire de Paris, for the official launch of the EU-funded project ‘Butterfly’. This bold, four-year interdisciplinary initiative is focused on the future of pollinators and the ecosystems that depend on them, and is one of a series of projects that have spun out from the EU’s Pollinators Initiative.

Over two days of lively discussion, the project’s key themes came into focus: the urgent need to restore pollinator populations, the value of integrating ecological and economic data, and the importance of including people—farmers, citizens, policymakers—in shaping practical, long-term solutions to pollinator decline.

Connecting Science and Policy

I arrived in Paris early Wednesday evening to be fresh for the meeting’s opening session the following morning. This set the stage by grounding the project in real-world policy contexts, including the EU Pollinators Initiative and the Nature Restoration Law. These frameworks are increasingly recognising the vital role pollinators play not just in nature, but in the economy and public well-being.

Nine Work Packages, One Mission

Participants got a crash course in the project’s structure through short presentations from each of the nine work packages. These range from ecological modelling and ecosystem valuation to resilience thinking, communication tools, and understanding human relationships with pollinators. A strong emphasis was placed on collaboration—how each work package connects with the others and contributes to the project’s broader vision. For example, one of my roles will be to work closely with Maria Clara Castellanos and her team at the University of Sussex on the integration of the UK-focused Database of Pollinator Interactions (DoPI) and the Global Biotic Interactions (GloBI) platform, to create an online European Atlas of Plant-Pollinator Associations (EuroAPPA). This in turn will feed plant-pollinator data into the modelling and economic valuation tasks in some of the other work packages.

Living Labs and Global Perspectives

One of the most exciting aspects of the Butterfly project is the network of “Living Labs” being established across Europe and the test sites in overseas territories. From Murcia to Martinique, each site represents a unique ecological and cultural landscape with its own pollination challenges. These test sites, some of which are shared with a parallel project called RestPoll, will serve as experimental spaces to co-develop and test strategies for enhancing pollinator resilience in real-world contexts. Another of my roles in the project is to help with the field work on the Caribbean island of Curaçao, where we will be assessing birds and bats as pollinators, as well as insects.

Thematic Sessions and Cross-Pollination

The meeting featured targeted discussion sessions on everything from economic modelling chains and ecosystem indicators to human dimensions like eco-literacy, historical agency, and “slow hope.” Again, one of my contributions will be to the work package dedicated to understanding and reacting to the human dimensions of pollinator decline, where I hope to provide a case study that builds on the work I published almost a decade ago on how the auction prices of holly and mistletoe are a reflection of the work of wild pollinators. In the evening we had a “cross-pollination” networking buffet dinner, themed around pollinator-dependent food crops, that provided an opportunity for participants to mix across disciplines, brainstorm, and spark new collaborations in an informal setting.

Laying the Groundwork for Action

Day two shifted toward practicalities—data sharing, financial management, ethics, and stakeholder engagement—as well as discussions about how Butterfly will connect with other major EU-funded projects, including VALOR, which is Butterfly’s partner and with which we will closely collaborate. Thematic sessions continued to dive deep into topics like mainstreaming pollinator stewardship and developing indicators to track the societal impacts of pollinator loss.

Looking Ahead

The meeting wrapped up with a plenary session with the project’s Advisory Board, reinforcing the importance of external perspectives in guiding the project’s evolution. Dinner that evening was an informal affair (not funded by the project!) at a really wonderful, traditionally French restaurant – Le Temps des Cerises – where service was slow, the food and wine were delicious, and the conversations continued to flow.

For those of us who stayed an extra day, a field visit on Saturday offered a first-hand look at urban pollinator research at the Jardin Écologique within the Jardin des Plantes—a fitting reminder of why this work matters! Here’s some photographs from that trip:

My sincere thanks to all of the colleagues who made the Butterfly kick-off meeting such a success: I look forward to working with you all over the next four years! Particular thanks to Paolo Biella who allowed me to use the photo at the top of the post, of a female mason bee outside our venue. We kept an eye on her during the meeting and I’m pleased to report that she successfully sealed up her nest. May her offspring thrive!

If you’d like to delve deeper into Butterfly’s objectives, here’s the project summary from our funding application:

Butterfly aims to significantly enhance society’s capacity to appraise, foresee, and respond to the threats posed by cascading impacts of pollinator decline. To reach that goal it will establish a test system of geographically well spread multi-actor communities across sectors for co-creating proactive pollinator restoration solutions and: (1) collect, integrate, manage and share ecological and spatial information on a wide range of known and lesser known pollinators and pollination services provided for wild and cultivated plants, across Europe and selected overseas territories; (2) advance the monetary and non-monetary valuation of marketed and not marketed direct and indirect ecosystem functions and services provided by pollinators, and advance ecosystem accounting; (3) comprehensively model and quantify the macro-economic implications of pollinator decline and country-specific economic butterfly effects of dependencies on pollinators, and assess policy options and scenarios; (4) assess how five key biomass supply chains (food/micronutrients, pharmaceuticals, cosmetics, biomaterials, biomass energy) depend on pollination and co-create pollinator restoration options that increase resilience of these supply chains; (5) devise, co-create, test and implement transferable tools, interactive atlases and guidelines that enable systematic mainstreaming of proactive pollinator stewardship in vulnerable sectors; (6) conceive indicators for human dimensions and assess and exploit the socio-cultural capacity of the concepts: ‘pollinator stewardship’, ‘ecoliteracy’, ‘historical agency’ and ‘slow hope’ in reversing pollinator decline. It will inform EU policy processes and build strategic alliances for high-level impact. The Butterfly network of Living Labs will accelerate knowledge transfer and uptake of new business models and serve as breeding place for multi-actor co-creation of knowledge and sustainable solutions, paving the way to pollinator stewardship in all sectors.