The event takes place in the Wilkinson Room, St. John’s Church, Hills Road. Doors open at 7pm and the talk begins at 7.30pm. There’s a £2.00 charge for non-members – more details can be found by following this link.
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:
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.
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.
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.
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.
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.
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.
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:
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!
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:
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.
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:
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.
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.
Prof. Jeff Ollerton - ecological scientist and author 