Category Archives: Birds

The mystery of what pollinates poinsettias – China Diary 3

Is it too early to talk about Christmas? Not if you’re interested in pollinators and pollination! The mid-winter festival has featured quite a number of times on my blog over the years, especially in relation to the iconic plants that represent this time of year in Northern Europe, and what one might describe as the ‘cultural biodiversity‘ of Christmas. The final plant that I included in that last post was the poinsettia (Euphorbia pulcherrima) – this is how I described it:

In many ways this is an unusual plant to have such a strong cultural association with Christmas: it’s a mildly toxic species of spurge from tropical Mexico that was introduced to North America in the 19th century, then subsequently to Europe. However its festive connotations date back to the earliest period of Spanish colonisation in the 16th century, so it’s older than some…other Christmasy traditions…

I also discuss poinsettia, and specifically its pollination, in my recent book Birds & Flowers: An Intimate 50 Million Year Relationship – this is what I say in the chapter called ‘Urban flowers for urban birds’:

Just occasionally one sees a bird-pollinated tree planted in a city. The most common in my experience are various banksias in Australia, and the Royal Poinciana (from Madagascar) and the African Tulip Tree in the urban tropics and subtropics elsewhere in the world. I’ve also occasionally encountered large specimens of Poinsettia: when they are given free rein they are a much more impressive plant than their Christmas cousins. The vivid red bracts that surround the clusters of flowers suggest that they may be hummingbird-pollinated in their native Central America, but as far as I know their pollination ecology has not been studied.

Here at the Kunming Botanic Garden there’s several quite large specimens of poinsettia that, as I write, are in full flower, their red bracts a signal to pollinators that can be seen for quite a distance. However we’ve not seen any of the local sunbirds or white-eyes visit the flowers, and, as I said in the book, as far as I know the pollination ecology of poinsettia has never been studied in the wild. Close inspection of the flowers in the garden revealed that almost all of the nectaries had at least one nectar-collecting ant sticking out from it, their prominent backsides a deterrent to the Asian Honey Bees (Apis cerana) that also wanted a piece of the action.

Based on the position of the nectaries in relation to the stamens, if the plant is hummingbird-pollinated then the pollen is likely to end up under the chin of the bird. That’s certainly been described in other plant-bird pollination systems. But it does not have to be birds that move the pollen around – red flowers are also associated with other kinds of pollinators, for example butterflies and beetles. But until someone in Mexico does the necessary field work, we’ll just have to speculate.

A new review of ‘Birds & Flowers’ in the Journal of Pollination Ecology

The reviews of Birds & Flowers: An Intimate 50 Million Year Relationship are starting to appear in blogs, magazines and journals. The latest, by Diane Campbell, has just been published in the Journal of Pollination Ecology and I’m so pleased that it was positive! I’ve only met Diane a couple of times at conferences but I have a lot of respect for her work. The review is fair and balanced, and gratifyingly enthusiastic, for example:

In this delightful book, [Ollerton] describes the ways that birds and flowers interact. As in his previous book, Pollinators & Pollination: Nature and Society, [he] takes a deeply personal approach to the subject. He combines anecdotes from his research travels around the world, to mountains of Kenya and Tanzania, the Andes of Peru, Brazil, and Nepal, among other places, with his contributions to, and masterful knowledge of, the recent literature…

The review is free to read and download from Journal of Pollination Ecology. I’m so glad that people are enjoying the book – if you’ve bought or borrowed a copy, please do leave a comment and let me know what you think.

The flower that’s pollinated by birds, bees….and the wind!

In my new book Birds & Flowers: An Intimate 50 Million Year Relationship I spend a bit of time discussing the idea of the bird pollination syndrome that we refer to as ‘ornithophily’, its limitations, and the fact that it has two distinct meanings that are often conflated. One of the problems with ornithophily, and indeed all of the syndromes, is that historically it’s sometimes blinkered scientists to the extent that they only look at the flower visitors that are “right” for the syndrome, ignoring the rest or dismissing them as “secondary pollinators”, a term I dislike.

Why do I dislike that term? Because it fails to capture the complexity of flower-pollinator interactions and relegates an important component of plant reproduction to a subsidiary role. I could go on about this at some length, but if you’re interested in discovering more, look at pages 62-65 of Birds & Flowers. There I contrast the classical Most Effective Pollinator Principle with the equally valid (but much less well studied) Least Effective Pollinator Principle, with a segue into one of my favourite tracks from Led Zeppelin’s second album: What is and What Should Never Be.

But back to the real subject of this post – a flower that corresponds to the classical bird pollination syndrome BUT is also pollinated by bees and (very surprisingly) wind! It’s such an interesting paper by Brazilian ecologists Amanda Pacheco, Pedro Bergamo & Leandro Freitas – here’s the reference and a link to the study:

Pacheco, A., Bergamo, P.J. & Freitas, L. (2024) An unexpected case of wind pollination: ambophily in an ornithophilous tropical mountaintop Orobanchaceae. Plant Systematics and Evolution 310, 9. https://doi.org/10.1007/s00606-024-01890-6

For over 100 years the classical pollination syndromes have acted as a framework for understanding the ecology and evolution of plant-pollinator interactions. But we’ve long known that while they can be a useful shorthand, they do not fully reflect the complexity of how pollination systems evolve. That shouldn’t surprise us because, as I point out in my two recent books, we have data (of any quality) on no more than 10% of the 350,000 or so species of flowering plants!

In addition, those plants for which we do have good data are NOT a random subset of the flowering plants: they have been specifically chosen by researchers because they look to be good systems with which to address particular ecological or evolutionary questions.

Which is fine, but we MUST recognise that this imposes significant restrictions on our understanding of the biodiversity of plant-pollinator interactions. The authors of this paper expressed it very well when they wrote that assumptions about:

“predictability may cause researchers to take for granted that only birds pollinate ornithophilous flowers, hindering research on the contribution of other vectors.”

To which I’d add: it also hinders our understanding of how these interactions evolve over long time scales and across multiple populations.

An obvious question is: how frequent are these sorts of complex pollination systems, involving different pollen vectors of an apparently specialised flower? The answer is that we simply don’t know, because most researchers would have not gone into this level of detail. So a huge congratulations to the authors for a great study – I hope it stimulates others to look beyond the ‘expected’ pollinators of flowers.

Photos: Nathália Susin Streher from the original paper.

Adaptable Elder – and a nice review of my book by Mark Avery!

One of the many things that I love about Common Elder (Sambucus nigra), and which I didn’t have space to properly convey in my article about the species last year, is just how adaptable it is as a species. The tree possesses a lot of what biologists term “phenotypic plasticity“. This is the ability of an organism to flexibly change aspects of its morphology or behaviour or physiology in response to differences in the environment. Plants are especially good at this because, if they find themselves growing in less-than-optimal conditions, they can’t just uproot themselves and leave for pastures new. This is obvious to anyone who has seen a houseplant struggling in a dark corner of a room: the poor plant will etiolate and bend as its yellowing foliage tries to reach the light from a distant window. The same plant grown on a sunny windowsill will be more compact, greener, and healthier.

When it comes to Elder, and indeed other trees, winter is often the best time to see this plasticity, when the trunks and boughs are not cloaked in greenery. On a coastal walk at Klintebjerg yesterday, I spotted three rather different phenotypes of Common Elder which nicely illustrate this environmental context dependency.

The first was a wind-tortured tree growing at the base of a low hill, directly in the teeth of the prevailing Kattegat weather, its trunk bent away from the sea and its branches lopsidedly pruned:

The second was a more fortunate specimen, growing in the lee of that same hill and allowed to spread its symmetrical arms, as though waiting to embrace any passing birds. It had clearly never been pruned back by the landowner, who had allowed it to grow as a fine, single-trunked small tree:

As we walked back down the hill via a narrow path, enclosed and over-topped by a fairy tale canopy of dense, twisted Blackthorn (Prunus spinosa), I spotted another phenotype, different again. I initially thought that they were the stems of a woody climber, perhaps Old Man’s Beard (Clematis vitalba) or European Honeysuckle (Lonicera periclymenum). When I looked closer it was clear that these were Elder, growing narrow and long, using the Blackthorn as support, as they struggled to reach up through the canopy to gain the light:

There were several individuals like this, presumably the result of seed dispersal by birds perched within the Blackthorn. I don’t think that I’ve ever seen Elder growing in quite this way before, but then how often do we get to peer deeply into the secrets hidden within a dense Blackthorn patch?

I had only planned to write about Common Elder today, but I can’t resist mentioning that, over on his blog, ornithologist Mark Avery has written a very nice review of Birds & Flowers: An Intimate 50 Million Year Relationship. He describes my book as having:

…a lightness of touch and tone that should not be taken for lightness of understanding….This is a fine example of a book which is pitched to increase the public understanding of ecology and evolution, and succeeds.

Thank you Mark, that’s very gratifying to read, and I’m glad that you enjoyed it!

Read my author interview and get a 25% discount off ‘Birds & Flowers’, ‘Pollinators & Pollination’ and other books from Pelagic Publishing!

I recently did a short interview with Pelagic Publishing’s marketing person, Sarah Stott, which you can read here: https://pelagicpublishing.com/blogs/news/birds-and-flowers-author-interview.

On that page you can sign up to Pelagic’s newsletter (which I STRONGLY recommend, because they produce some great natural history and science books, and not just mine!) and by doing so you can receive a 25% discount on all orders.

What are you waiting for?

It’s publication day – “Birds & Flowers” is officially out!

After what seems like a long wait, for me at least, today marks the official publication of Birds & Flowers: An Intimate 50 Million Year Relationship! I received my advance copies on Friday, an event that Karin commemorated with a short unboxing video:

https://www.facebook.com/100000638827245/videos/2177574652581431

It’s been a long journey from pitching the initial idea to Pelagic Publishing back in early 2021, through the various drafts that have culminated in the finished book. As you can see from the images on this post and the endorsements on the publisher’s web site, Birds & Flowers has so far been warmly received. I hope that future reviews are as positive!

A few people have asked me what’s next. In fact I have definite plans (as in topics, provisional titles, the start of chapter structure, and even some initial writing) for three more books. The next one is actually about half written, but then I have been working at it, on and off, for 30 years! Watch this space for more details…

In the shorter term, Karin and I are returning (permanently) to the UK at the start of March. We’ve enjoyed our time in Denmark, it’s been a fun two and a half years, but we’re missing our immediate family plus we both have some interesting work possibilities to pursue. In mid-April I will be going to China for three months to work with my colleague Zong-Xin Ren at the Kunming Institute of Botany. I’ll be sure to blog about my adventures there!

In the meantime, if you buy my book or borrow it from the library or from a friend, please let me know what you think in the comments section below.

Read a preview of my new book ‘Birds & Flowers: An Intimate 50 Million Year Relationship’

In the run up to release of my new book Birds & Flowers: An Intimate 50 Million Year Relationship, my publisher, Pelagic, has updated the book description and provided a preview of some of the pages and colour plates – follow this link to view them. On that page you can also pre-order the book direct from Pelagic Publishing, who will ship worldwide, or it’s available from many of the online book sellers.

I’m really excited to be sharing this with the readers of my blog and can’t wait for publication day! Early in 2024 I hope to do some talks, online and in person, to promote the book – so watch this space.

With best wishes to you all and hopes for a peaceful, and more sustainable, New Year.

The one thing I wish more people understood about flower pollination

Obviously the title of this post is click-bait, as there’s LOTS of things that I wish more people knew about pollination! But here’s one that really gets my (Yule) goat.

I’ve lost track of the number of times that I’ve read statements in books and research papers such as “bees collect lots of pollen from flowers therefore they are good pollinators”. Even worse, I sometimes see studies where pollen has been removed from “pollen baskets” or other scopae, then used as a measure of the importance of those bees as pollinators.

In both cases it seems to have been forgotten that bees are collecting pollen to feed their larvae and pollen that ends up in scopae is generally not available for pollination.

That’s the purpose of the Venn diagram at the top of this short post, to remind us that there can be a disconnect between what bees are doing and what plants require: foraging for pollen only partly correlates with flower pollination. Indeed, the same argument applies to any animal that feeds itself or its young on pollen, including pollen wasps (Maserinae), Heliconia butterflies, and some flower-visiting hoverflies, birds and bats.

It’s not only loss of pollen from reproduction that’s important here: depending on the size and behaviour of the bees relative to the shape and size of the flower, they may go nowhere near the stigma, so even if they are carrying viable pollen, it can be lost as far as the plant is concerned.

Note also that many bee species will collect pollen from wind-pollinated plants such as grasses, oaks, etc. Indeed in some species the availability of such pollen is extremely important – see Manu Saunders’ review on this topic and more recent papers that cite it. Again, it emphasises the partial disconnect between pollen collecting by bees and pollination of flowers by bees.

Assessing which flower visitors are actually pollinators is not technically demanding but it can be time consuming. The minimum that you need is single visit deposition (SVD) experiments in which you expose unvisited flowers to one visit by the potential pollinator. Then you assess how much pollen has landed on the stigma or (better) whether the visit results in seed set.

If you want to know more about the evidence that’s required to determine if a flower visitor is or is not a pollinator, they are codified in the “Cox-Knox Postulates” that I discuss in my book Pollinators & Pollination: Nature and Society.

Corrections to the first edition of “Pollinators & Pollination: Nature and Society”

Books are never perfect. In the run-up to publication of Birds & Flowers: An Intimate 50 Million Year Relationship, I am all too aware that this is a truth that’s a cause of anxiety, and sometimes sleeplessness, for all authors. One category of imperfection is tipographical* errors have been introduced at some point in the process of writing and editing. In the past these were corrected in the first edition of a book by the inclusion of errata slips, and such errors are sometimes important in determining the true first editions of older books. On page 20 of the first edition of Darwin’s Origin of Species, for example, there is a misspelling of the word “species”**. This was corrected in the second edition but is an important marker of an extremely valuable book, intellectually and (now) commercially.

A second category involves errors of fact or interpretation or expression that, with hindsight and reader feedback, require correction, or at least acknowledgement, by the author. These are the ones that really make an author squirm inside, even though we know that they are inevitable: we are, after all only human.

It turns out that there are a few examples of both categories in the first edition of my 2021 book Pollinators & Pollination: Nature and Society. Some of them have been corrected in the second edition, but if you purchased the first edition then these are what you should look out for:

P22 – ‘Unmated queens and males (drones) are produced by the colony later in the season’ changes to: ‘Unmated queens and males (drones) are produced by the colony from spring onwards.’

P30, Fig 2.9 – Correct ‘Tabaernemontana’ to Tabernaemontana

P51, Figure 3.8 – title – it should read C. rhynchantha [there’s an h missing]

P57 – ‘The bank that Darwin was referring to is on his property at Down House in Kent, and it was one he observed many times during his walks through the garden.’ changes to ‘The bank that Darwin was referring to is near his property at Down House in Kent, and it was one he observed many times during his walks in the area.’***

P146 – ‘I’ve even see them attack and kill honey bees’ should read: ‘I’ve even seen them….’

P169 – in the title for Figure 10.5, Anon (2019) should be Anon (1919) [in some presentation copies of my book I have corrected this and initialed the change]

P259 – this reference: Klein, A.-M., Steffan-Dewenter, I. and Tscharntke, T. (2003) Fruit set of highland coffee increases with the diversity of pollinating bees. Proceedings of the Royal Society B 270: 955–961. doi: 10.1098/rspb.2002.2306.

Should be replaced by:

Klein, A.-M., Steffan-Dewenter, I. and Tscharntke, T. (2003) Bee pollination and fruit set of Coffea arabica and C. canephora (Rubiaceae). American Journal of Botany 90, 153– 157. doi: 10.1046/j.1365-2664.2003.00847.x

The last two have yet to be corrected and will need to wait for the third edition:

P119 – the Rader et al. study did not include birds and bats, just insects.

P262 – “Nabhan, G.P. and Buchmann, S.” should read “Buchmann, S. and Nabhan, G.P.”

That final error is really embarrassing because, as I point out in the chapter ‘The Politics of Pollination’, their book The Forgotten Pollinators was an inspirational one for stimulating research and action around pollinator conservation! I can offer no explanation for why the order of the authors got reversed in my head.

My sincere thanks to those readers who pointed out some of these errors. My hope is that Birds & Flowers has fewer, but I may be fooling myself…

*You see what I did there?

**Proof-reading is boring and soul-destroying for any author, but really Mr Darwin?!

***If there is an after-life, I’d like to think that Darwin’s now enjoying this error after my snarky comment in the second footnote. To which I’ll respond: watch out for a doozy of a footnote about a Darwin footnote in Birds & Flowers!

“Birds & Flowers” book update: here’s the list of chapters!

Today I returned the final, edited files of the book manuscript to the publisher. It’s been a long summer of ‘fine distinctions and nice judgements’, to quote my editor, the inimitable Hugh Brazier. Now that’s all finalised, I thought that it was time to share the chapter titles with you – here goes:

Introduction: Encounters with birds and flowers

1         Origins of a partnership

              Understanding 50 million years of bird and flower evolution

2          Surprising variety

              The astounding diversity of pollinating birds

3           Keeping it in the family

                 Accounts of the different groups of bird pollinators

4          A flower’s point of view

              How many plants are bird-pollinated, and where are they found?

5         In the eye of the beholder

              What do bird flowers look like?

6          Goods and services

              The enticements given to birds for pollinating flowers

7         Misaligned interests

              The ongoing conflicts between flowers and birds

8          Senses and sensitivities

              How bird brains shape the flowers that they pollinate

9          Codependent connections

                Networks of interacting flowers and birds

10        Hitchhikers, drunks and killers

              The other actors in the network and how they affect the main players

11        The limits to specialisation

              How ‘specialised’ are the relationships between birds and flowers?

12         Islands in the sea, islands in the sky

                  Isolation, in oceans or in mountains, results in some remarkable interactions

13         The curious case of Europe

              Why did we believe that Europe had no bird-pollinated flowers?

14         ‘After the Manner of Bees’

              The origins of our understanding of birds as pollinators, and their cultural associations

15        Feathers and fruits

                Birds as pollinators of edible wild plants and domesticated crops

16        Urban flowers for urban birds

              Bird pollination in cities and gardens

17       Bad birds and feral flowers

              The impact of invasive species

18         What escapes the eye

                 The decline and extinction of bird–flower relationships

19         The restoration of hope

                  People as conservationists of birds and their flowers

There you have it! I’m incredibly excited that the book is now just about finished (I still have to proof read the typeset text and produce an index) and I look forward to finally having a copy in my hands. Birds & Flowers: An Intimate 50 Million Year Relationship is available for pre-order from Pelagic Publishing, or via online bookshops.