Transcript
Speaker: Step into the Gardener's Lodge with me, Michael Haw. Let's explore the fascinating worlds of gardening, nature and ecology through conversations with experts, thought leaders, passionate enthusiasts, and of course, some real good friends.
Speaker: All from the cozy heart of the lodge. Come on in.
Speaker: Hello and welcome back to the Gardener's Lodge podcast after what has been a bit of a summer hiatus. Yes, I actually got very, very, very busy in my business over the summer, which is, I'm not gonna complain about, it's amazing and I'm very grateful. But it did mean that I slacked a little bit on the podcast production, but fear not, I am back with a vengeance and I have a slew of amazing guests coming up. You know, the summer in London,
Speaker: was bloody hot. And I know that's strange coming from an Australian, but ah yeah, it was a struggle. I've got to tell you, it was a struggle. There's something different about the heat here, I swear. And ah that heat saw massive changes in the environment around us. Everything was dry and brown and still is, and is still slowly recovering. We have had very little rain Still, we can see how it's impacting the grass and the trees and the and and the plants around us, not well, but how is that impacting these smaller creatures in our lives, the pollinators? Which brings me to today's guest.
Speaker: Professor Jeff Ollerton. He's an ecologist and an expert on a pollination. In fact, he's written two books on the subject. He is also an academic and just an all-around great guy. We covered a lot of topics to do with pollination from the pollinators themselves through to the mechanics of pollination, misconceptions about pollinators and pollination,
Speaker: And also i actually left the conversation feeling a little bit hopeful for the future. Let me know what you think. But without further ado, we have to ask Jeff our six rapid fire questions. Jeff, are you ready? I'm ready. Favorite plant.
Speaker: Favourite plant? Ooh. I'm going to say Syripeggia woodyae, which will be the string of hearts plant, which is often grown as a house plant. Favourite way to connect with nature?
Speaker: Going out into an area that I've never been to before and taking my time to walk slowly through it. Paying attention with all of your senses.
Speaker: Most beautiful garden or natural landscape you've ever visited? oh wow. ah I'm actually going to give a shout out for Oxford Botanic Garden. Favourite garden tool or tool of the trade?
Speaker: Oh, my daughter Ellen bought me one of those Japanese knives, which... A Hori Hori knife? That's the one with a kind yeah of curve to it. Yeah,
Speaker: If you could be one, a plant or an animal? um A plant, so a very long-lived tree. And finally, when you're looking for the most reliable information on anything garden or nature related, where do you first turn? Depends on the nature of the information.
Speaker: um People are going flame me for this, but actually, you know, Wikipedia is becoming more and more reliable now. now that they've been in you know now they've put more um more checks and balances restrictions checks and balances restrictions on who can who can edit and and so on it's become much more reliable uh and uh i've done some editing of of wikipedia pages in the past i know about scientists who who have so actually as starting point wikipedia is is pretty good Grew up in the northeast of England, in what was at one time the industrial heartlands of of England in Sunderland on the coast.
Speaker: Not the typical rural idyll that we associate with with so many other ecologists and naturalists. But one of the things that he did have when I was growing up was a lot of areas that were post-demolition, some of it was slum clearance, some of it was areas that had been bombed in the Second World War. Those post-industrial areas had been really just allowed to run to run wild. And so i I encountered a huge amount of nature within a sort of mile, half a mile radius of of of my home.
Speaker: Simply things that had recolonized those sites. But the other thing that was really important was that my father had an allotment a community garden not far from the house that he would take me to regularly um and he grew plants down he had a greenhouse and that definitely had ah an impact on on my formative years and in fact to to this day the smell of tomato leaves on a hot day um god takes me straight back
Speaker: to being in that glass house with with my dad. It's one of the best smells, I think. Oh, it's incredibly e evolve incredibly evocative. Yeah, so so so that's my background. Then from there it was, you know, going to college, university, PhD and so on. But those were the those were the formative times.
Speaker: You've written something like 190 scientific papers, you've written two books titled Pollinators and Pollination, Nature and Society, which was released in 2021. And then your latest book, which was the birds and flowers, an intimate 50 million year relationship, which I don't even know how you begin to like dig back into 50 million years, but you've done it. um But because you are focused around pollination, you just explain at a basic level, what is pollination? As with so many things, it all revolves around sex and reproduction. So for...
Speaker: Most animals, finding a mate is relatively straightforward. ah They can move around. They can use visual signals or sound signals, the case of birds, for example, or scent, in the case of most most mammals, to locate a mate.
Speaker: ah Plants can't do that. Plants are sessile. They sit where they are, largely. There's a few exceptions to that, but generally speaking, they they sit where they sit where they are. They can't move around to seek a mate. So what they have to do in order to reproduce is to bring in a third party. At the back of my mind, I'm saying, don't say thruple, don't say thruple.
Speaker: Don't say thruple, but I'm going to say thruple. So they need to bring in it bring in a third party, okay? And that is a third party that will transport the pollen, which contains the male sex cells, equivalent of sperm,
Speaker: From one flower to another flower where that pollen lands on a stigma, which is the receptive female surface, that pollen then germinates. It sends a pollen tube down through the stile, which is the elongated part often of the flower. If you consider a lily, for example, the male sex cells travel down that pollen tube ah into the ovary where the ovules are sitting, the female eggs, if you like.
Speaker: and then the male sex cells fertilize the ovules. So that's the the the principle, that's the basis. I mean, the the analogy or or the similarity with with animal sex is is quite striking.
Speaker: Where it differs is the way in which that pollen gets from one flower too to another. And there's broadly three ways that it can and happen.
Speaker: um It can happen via the wind. The pollen is moved around on wind currents. And anybody who suffers from hay fever knows that that's pretty common. Most grasses are wind pollinated, for example. Many trees, oaks, and and so on are wind pollinated. um It can happen by water.
Speaker: And so there are aquatic plants which are water pollinated. The pollen is shed into the into the water and the current the water currents move the pollen around in the same way that wind currents move wind pollinated pollen around.
Speaker: ah The third way that it happens and the most common way that pollen is dispersed is by animals. And by animals here, i'm I'm talking in the zoological sense of the kingdom, animalia, which includes birds and includes mammals and includes reptiles and includes the insects.
Speaker: And it's the insects which are the dominant pollen vectors, if you like. um And that movement is facilitated in in many different ways. um It can be facilitated by rewarding the pollinator.
Speaker: So, for example, bees will hunt out flowers of certain shape and colour and scent that they visited before, and which has provided them with a nectar reward or possibly pollen to take back to their nest to to feed their larvae. And so they go searching for the same kind of flower.
Speaker: um It can be mediated by other kinds of rewards. So there are some flowers, for example, that produce um resin, which are which is picked up by bees and is then used for constructing bee nests.
Speaker: um There are other flowers which don't produce any reward at all, and they're effectively fooling the the pollinator into visiting them. um So sometimes they smell of rotting flesh or fermenting fruit for example and um and they're providing any kind of a reward so in a sense they're almost kind of parasitizing the uh the pollinators fooling them into it they're fooling them into it so it's so it's complex uh why is it so important uh it's important because the terrestrial realm encompasses 30 percent of the planet know the rest is is oceans of course um is largely dominated by flowering plants
Speaker: And it's the flowering plants which are the main ones which are animal pollinated. Having said that, there are some conifer relatives, some cytads, for example, which are insect pollinated as well.
Speaker: um but But without the pollination, we wouldn't have those populations of of wild plants. um And without those populations wild plants, we wouldn't have the populations of animals which depend upon those wild plants. And of course...
Speaker: Including ourselves, absolutely. Including ourselves. i was just going to say, you know, its pollinators, of course, are important in agriculture. Anybody who's grown beans and tomatoes and apples and ah cherries and so on in their inner garden know know that. ah Something like three quarters of our most important crops are insect pollinators, mainly insect pollinated, but some bird and bat pollination to to some degree.
Speaker: Yeah. I mean, the the other way of pollinating, of course, is self-pollination. um Well, it's considered a little bit of an evolutionary dead end, and it's not a good idea to be constantly breeding with yourself because you then lack that kind of genetic diversity which allows a population to evolve in the future. Having said that, a lot of a lot of plants have evolved it.
Speaker: lot of garden weeds, for example, are ah mainly self-pollinating. um Dandelion, and certainly in in northern Europe, dandelion populations are mainly not quite self-pollinating. They use a different system, but but essentially they've they foregone ah the need for for pollen to arrive on the on the stigma, which is a little bit of a paradox that nobody's ever really worked out. that The fact that dandelions don't require outcrossing pollen, yet they still produce a lot of nectar and are really important for urban pollinators in in particular. It's a little bit of a paradox that nobody's really figured out. That is really interesting, actually.
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Speaker: While we're on the subject of evolution, I think that a lot of people think that, you know animals adapt to plants or use them as resources. And that's sort of like they' they've kind of always been there. And then animals have come and exploited them, including us for shelter, food. But it's actually far more of like a dance between the two, a co-evolutionary dance between the two where symbiotic relationships have evolved together.
Speaker: Could you explain that concept a little bit? Okay, well well, what you're really talking about there is mutualism, mutualistic organization and interactions between organisms in which both species benefit. um but i'm I'm going to get on my soapbox here and say that symbiosis is one of the most misunderstood and misused words. Okay, have I misused it? that' ah yeah A little bit, yes. So mutualism can be symbiotic,
Speaker: But it doesn't have to be. ah So not all mutualism is symbiotic and not all symbiosis is mutualistic. So symbiosis, if you break the word down ah into its original Latin or Greek, it really just means close biology.
Speaker: And close biological relationships take lots of different forms, including parasitism. So when you've got ah parasites that are very um closely adapted and closely and involved with their with their host, that's a form of symbiotic parasitism.
Speaker: um So mutualism can be ah symbiotic. So the gut bacteria that you have in your body at the moment, that all of us have in our bodies, unless we've been on a course of really, really strong antibiotics,
Speaker: are living very very closely with us uh we're providing them with food when we eat they are helping to break down ah that food and ah improving digestion in our gut now that's mutualistic because we benefit and the bacteria benefit It's also symbiotic because they are spending their largely spending their whole life cycles within within our bodies. I'd describe that as
Speaker: There's a symbiotic mutualism. um As soon as you get a bacterial infection in your lungs or ah wherever, um that's a parasitism.
Speaker: ah the yeah the The bacteria is parasitizing you, and but it's also simply it's also symbiotic. It's close it's close living like that. So most plant-pollinator interactions are mutualistic in that the plant benefits because it it's it it did is able to reproduce.
Speaker: The animal benefits because it gets a sort of food or sort of set shelter or a supply of resin for building a nest in in some cases as well.
Speaker: ah So they're they're mutualistic. But most are not symbiotic. B visits a flower and then it moves on to one another the flower and then it moves on to one another the flower. There's not that close biology.
Speaker: ah guess The symbiotic pollination relationships are things like figs and fig wasps where the fig wasp is and of which there are many species and the figs of which there are also many species their life cycles are closely entwined um i'm i'm very conscious that this is turning into a lecture this is what this is this is my 30 years in higher education i've got to say though this is interesting no this is a good basis so so yeah so so uh you know although we talk about relationships being symbiotic or not symbiotic actually it's a continuum
Speaker: Yes. You know, ah ah at the one hand, you if we're just thinking about pollination for for a moment, on the one hand, you have relationships that are clearly symbiotic and clearly co-evolved as well, meaning that both or that both organisms have evolved to one another ah to undertake that that interaction, you know? um so So you have these symbiotic co-evolved relationships at one end of the spectrum,
Speaker: figs and fig wasps are one example yuccas and yucca moths are ah are another example there's a handful of examples there yeah at the other end of the spectrum you have most of the relationships as i say of of bees visiting poppies or or being members of the bean family the legumes and so on of it but where it's not a close co-evolved relationship in the middle of of that but that's that sort of binary divide, you have a whole set of other kinds of interactions that are more or less symbiotic or more or less close in their relationship. So an example would be a b which visits flowers, a wide range of different flowers for its nectar requirements.
Speaker: but only takes pollen from one particular species or one particular genus or one particular family of plants to then take back to its nest to feed to its its larvae and a good example there would be ivy bees in britain for example which colonized in the last 20 years or so and have spread is a natural colonization event possibly driven by climate change um They've now spread across certainly most of England into into Scotland and over into Ireland as well, where and the adult bees will visit a range of different flowers for nectar, but certainly in Britain at least, they only really take pollen from ivy to then feed to there.
Speaker: to the developing bees, the larvae in the nest. People often think that bumblebees or bees are what pollination is, but reality is it's a huge array of species of not only insects, but of what birds, bats, what are the kind of key groups of pollinators?
Speaker: That's a really good question, and the answer depends. ah It depends where in the world you are. You asked that question in Australia, you get a very different answer to to to in Europe. um But I mean, to give you some sort of you some ideas of of this diversity here, the most diverse group of um of pollinators ah by a country mile are the moths.
Speaker: I mean, the moths are incredibly diverse. You know, I'm now trying to rack my my memory to remember how many species of moths are. i'm going to say 170,000, but don't hold me to that. But it's I mean, that's two orders of magnitude more than there are bees, for example. I think there's probably 25,000 to 30,000 species of bees. and So that gives you a sense, know, two orders of magnitude more moths. The reason we don't appreciate them so much, of course, is they're mostly nocturnal.
Speaker: um And most pollination scientists who go out and study these things are diurnal. So they don't go out so much at night. But but the butterflies as well. but Globally, the butterflies um are more diverse than the ah then the bees. ah Flies, true flies, the diphthora are um a more important. Well, not more important, but them they're more diverse than the the bees. Beetles are as well.
Speaker: But probably the the bees get more of the um or the attention because as a group, they are so closely associated with with flowers, both as adults feeding on nectar ah and as larvae.
Speaker: as lobby feeding on on the pollen there. And there's something that captures the the human mind about a bee, I think, as well, which which makes them kind of like the the poster child in a way for but pollination. Yeah. And and and that's that largely comes from, of course, the the culture and folklore and husbandry around honeybees, ah particularly the Western honeybee, Apis mellifera, but there are other species of honeybees.
Speaker: ah The problem with that is actually honeybees are very unusual bees. Of the 25,000 or so ah bee species, less than 10% are actually social in the sense of having a queen and having workers and and so on.
Speaker: ah You know, the main groups of the honeybees, the bumblebees, some of the sweat bees ah in in tropical areas as well. But most bees are ah solitary. they they The females make a nest, but they don't have workers to to do the working for them.
Speaker: If anyone's interested, i have an episode with Clancy Lester, who's an Australian native bee expert, and he goes into ah insane detail about solitary bees. It's quite fascinating. Bee experts often go into an insane detail about but about the bees that they love. and They're a fascinating group of of insects. But then, you know, if we move beyond the insects, the ah the the birds, for example, there's probably three, four thousand perhaps species of of birds which act as pollinators globally. uh in the new world in in the americas it's hummingbirds that are the main ones but there's a whole range of other families of birds that do it as well moving to africa and and asia um and it's the the sunbirds which are the most obvious ones but again there are other groups of birds that do it and of course in in australia you've got the the honey eaters and and some of the parakeets as well that do it um so and and you have
Speaker: Plants which are specifically adapted to to bird pollination. um And then there's bat pollination as well. um A phenomenon that occurs on islands in particular is lizard pollination.
Speaker: So I've i've done a lot of field work on Tenerife, for example, and we see lizards there visiting visiting flowers. um Phenecta? Yeah, Phenecta.
Speaker: interesting yeah i suppose because they there's limit very limited resources on on islands that they kind of have to evolve to use what's available to them which that's fascinating yeah exactly do those lizards like are those liz do those lizards look different have they adapted different faces to be able to get into flowers or not Not specifically. And and they're omnivorous. you know they'll eat yeah They'll drink nectar. ah They'll eat fruit. ah They'll eat insects as well.
Speaker: um But then that's i mean that's true of of ah pollinating birds as well. o it's It's fascinating, isn't it? I do wonder with it being, it's been such a hot summer, hasn't it? It's yeah um been disastrously hot. Even for an Australian, it's been hot here. And the landscape has changed so dramatically, so quickly. yeah Everything's browned out. The soil is cracking, it's dry. How does that affect our pollinators? In different ways, depending upon the group of pollinators that your but you're talking about. We're now starting to build up longer term data sets to see um you know what the general trends are, um how our pollinator populations are are changing. um
Speaker: So if we think about bumblebees, for example, the hot summer last year and the hot summer this year, have resulted in a decline in most of our bumblebees, um some some dramatically so. and And I think the headline figure overall that I read was something like a 40% decline in bumblebee numbers.
Speaker: um And some species are being hit more than others. Red-tailed bumblebee, for example, Bombus lapidarius, has had a big population crash. Now, is this a permanent crash? Is this going to continue to decline? Or are we looking at that they will subside for the hot years and then they'll be out in in in more wet years in the future? ah In cooler, wetter years, they'll almost certainly bounce back. The thing thing you've got to understand about bumblebees is that they ah largely evolved in...
Speaker: cooler environments. They probably evolved in in Central Asia, particularly in the mountains of Central Asia, then have spread out from from there. And if you look at the areas where bumblebee diversity and abundance is is greatest, it tends to be in, you know,
Speaker: cooler parts of the northern hemisphere um and that's why they're relatively large they're relatively hairy and uh your listeners may or may know that this but uh they can actually generate their own body heat so we think of insects as being cold-blooded and most are but there are some that can generate their own body heat And bumblebees do it by vibrating the muscles in their thorax, and that generates heat they can warm there their bodies up. So that's why you can see queen bumblebees flying on relatively cold, sunny January and February days, for example, looking for looking for nesting sites. so
Speaker: With a group of organisms like the bumblebees, these kinds of hot, dry summers are really not good for them. I haven't seen a red-tailed bumblebee in my garden this year, and that's really unusual because they're such a common species.
Speaker: The bumblebees that I am seeing, many of them are very, very small, much smaller than than usual. too have noticed that, yeah. Yeah, and that's that's always a sign that there's there's less resources available for them.
Speaker: So, ah will they recover from this? Yes, the populations can can recover and in the future they could they could bounce back, but that very much depends on what our summers and our winters are going to be like in the in the future.
Speaker: When people hear about climate change, they often imagine species just completely disappearing. But before the extinction of these pollinators will happen, A relationship between the pollinators and the plants breaks down. What does that end up looking like in that intermediate period? We can imagine, what we can model is that if we think about the the population sizes of the pollinator and the the plants, ah the population sizes of of of them dropping down to a level where they they still exist. They haven't gone extinct within an area.
Speaker: you know ah But they're at such a low population density that they can no longer encounter each other. And so ultimately, that will but that that process can can happen slowly. You get to a tipping point, and suddenly it happens quickly. Because if they' if they're mutually dependent upon one another, the point at which they can't fulfill that mutual dependency means that they will decline very quickly. Crash.
Speaker: the As a general rule, it's the insects which would be lost much more quickly than the plants. The plants could still hang on.
Speaker: ah for example a tree, for example, ah could could survive, if it's a large, long-lived tree, could survive for hundreds of years um without its pollinator.
Speaker: Yeah. Yeah. it sit It sits there. It can't reproduce every year, but as an individual, it can it will be theyll yeah survive. And we see examples of this, for example, in Hawaii, where there are plants there which were bird pollinated in the past.
Speaker: Those birds have now gone extinct or or in some cases, again, are at very low population densities. And the the plant itself still exists as a population.
Speaker: In some cases, Hawaiian conservationists are hand pollinating those those flowers to ensure a supply of seeds into the future. But in other cases, the the populations are ah sitting there almost like ghost populations. They're not doing it they're not reproducing, ah but it's a kind of ah what we term an extinction debt.
Speaker: um having said all of that if we go back to what i was saying about symbiosis and this continuum yeah uh from very highly co-evolved relationships through to more generalized relationships most plant pollinator relationships exist at the more generalized end of that spectrum so they There can be an asymmetry to this.
Speaker: So you can have a plant which has multiple different pollinators, um as pollinated by bees and butterflies and hoverflies, for example.
Speaker: um And amongst those insects, most of them visit other flowers as well. But you might have one insect species within that that is completely dependent upon that plant.
Speaker: So if the population level of that plant drops down, most of those insects will move on to ah two other other plants. Whatever is surviving. Whatever is available, ah except for that one species which is which is dependent upon that plant.
Speaker: And it has the potential too to go extinct. We've actually done some experiments. um kind of testing this in the field where we've gone into grassland sites.
Speaker: We've ah looked at what we term the plant pollinator network. We can think of it as a network of of interactions. okay So we do standardized surveys.
Speaker: ah We look at at what's visiting the ah the plants. We look at the abundance of the plants, the abundance of the insects as well. We go away. We leave it to settle down following our disturbance for a little while.
Speaker: and then we go back and having established which is the most generalized plant, which is usually the most abundant and often you know a member of the daisy family, for example, we then hand remove all of those flower heads from the site, go away and then come back and see what effect that has had on that network there. So we did it we first did it in Northampton w over 15 years ago now. um And the um the most generalized and most abundant plant species there was a thing called Fetal scabius, now T. R. Vensis, a very common ah grassland species.
Speaker: ah So we went in there I paid um a bunch of students, 50 quid each plus lunch, to go in there. We hand pulled something like 25 000 flower heads out of this heard of this site to then see to see what the effect the effect was um when we went back and did the the resurveys what we found was that the abundance and diversity of the pollinators hadn't really changed interesting all they all they'd done was to move on to the next most abundant plant
Speaker: that was there we then allowed the field scabias to to regrow you know we were just pulling off the the open flower heads or plenty of flower buds there uh we allowed it to regrow then resurveyed and what happened was all the pollinators then moved back onto onto those onto those so so i think this is one of the things which which is now that's a small scale experiment in a relatively small grassland ah we've actually repeated it ah in the Czech Republic and those papers are published now um and we see very very similar similar patterns. They're small scale surveys but they do tell us something important about the flexibility of most pollinators to move between the ah between the resources that are are
Speaker: most abundant at the time. That does give us a little bit of hope, I suppose. it It does give us give us hope because, you know, the the the okay the bumblebees are doing really badly in Britain at the moment. And probably, but you know, in fact if I wanted to predict this, if if if these long, hot, dry summers continue and the warmer winters continue, what we're going to find is our bumblebee populations are going to be moving further and further north.
Speaker: whether they and and and further and further uphill, if you like, into hills and mountains. yeah But behind them, the solitary bees, most of which have evolved in warmer, drier environments. So if you look at the at the the hotspots of diversity for for solitary bees, it's places like the Eastern Mediterranean, for example, southern Spain, ah these very warm, dry areas which really suit solitary bees.
Speaker: they're doing really well and and the potential then is for them to take over at least some of the pollinating functions of the of the bumblebees. ah That in itself, there's ah there's a lot of complexity and nuance in there. I don't want your your listeners to think that Jeff thinks everything is okay because the solitary bees will take over from from the bumblebees. That is not what I'm saying. But what what I'm saying is that it's not a matter of that.
Speaker: All of the bees, all of the pollinators are going good to go extinct. I mean i i don't know if you've seen it in your garden or when you've been been out and about in the in the countryside, but ah butterflies are having a really good year at the moment yes i was thinking this i'm seeing a huge amount yeah lots and lots of butterflies at the moment because they like the hotter drier conditions mostly again that's ah that's ah a generalization but they're doing really well and you know a few years ago we were saying um oh all the butterflies are going to going to be lost because the winter is because the summer is is too cold and wet yeah generally speaking they don't like cold wet summers
Speaker: but they do prefer hotter, drier summers they're doing okay at the moment. So there is a lot of flexibility within these ecological systems, which we so sometimes don't give them credit for.
Speaker: I suppose then we really are worried about those very narrow relationships between a single plant and a single pollinator. Yeah. Phenological mismatch is what that is called. Could you explain that concept in a little more detail? Phenological refers to phenology, and phenology is the study of the timing of biological events.
Speaker: So all plants and animals and fungi as well have ah have a phenology in the sense that there is there are times when they are active, there's times when they're hibernating, there's times when they're reproducing There's times when they're growing. There's times when they lose their lose their leaves.
Speaker: And for plants and pollinators, the timing of when a plant flowers versus when a pollinator is active um can be really, really critical.
Speaker: It can be really critical for that plant ah if it only has a single pollinator and it can be really critical for the pollinator if it only has ah a single host plant. Mismatch can potentially happen when the kinds of environmental cues that a pollinator or a plant ah use to determine when they flower or or when they they emerge from from hibernation ah go out of out of synchrony.
Speaker: um Most plant-pollinator interactions are cued to the same sorts of environmental ah phenomena.
Speaker: Could be temperature. could be rainfall, for example. Light availability or something like that. Could be light availability. There are some suggestions that it might be happening with winter active bumblebees in Britain.
Speaker: So Bombus terrestris, the buff-tailed bumblebee, which is yeah one of our commonest and and certainly one of our earliest emerging bumblebees. We know that ah in the southwest of England in particular, and in London, you've got colonies there which are active for 12 months of the year.
Speaker: um Now, well if the workers are coming out in the middle of December and there are no flowers available for them, then that a colony ultimately will will starve.
Speaker: um But the reason that they're coming out in in winter is because you know in London there's a sort of heat island effect on on top of climate change. And so you've now got essentially a Mediterranean climate in um in London. You really don't get the the heavy frost that you used to get. And there's still a lot of ah plants in gardens, for example, non-native plant species, which are available for ah bumblebees.
Speaker: Rosemary is a really good example. Rosemary can be can be flowering very, very early in the season, even in in the winter. um In the southwest of England, where there's always been a milder climate there, of course, it might be more problematical, particularly with the native plant species that might not be flowering so so abundantly.
Speaker: But that's what we mean by the potential for phenological mismatch. but But again, there's there's a lot of, you know if it's going to happen anywhere, it's probably going to happen in places like alpine environments.
Speaker: where you have a very narrow window for flowering and and activity. Springs are late and winters come early, so you have this very narrow window of opportunity for for things to emerge into and to reproduce, I suspect. And and and similarly, actually, up in the in the Arctic, there is some suggestion that there's some mismatch between particularly some of the fly-pollinated shrubs up there and the flies which are emerging. later um but again there's there is a lot of flexibility built into the systems here which which makes which makes you know complete sense if we if we think about the lifespan of a plant species or an insect species most of the species that were that were familiar with have probably existed for uh 500 000 years a million years perhaps
Speaker: um Over the lifespan of a species, there's been multiple ah um multiple times when the when climates have changed, when the ranges have had have had to shift, um when there might be possibly a phenological overlap and and so on, yet they still persist to to this day because those kinds of global changes or regional climate changes ah will have weeded out those species which are are sensitive to that
Speaker: to those kinds of those kinds of changes. Here's something which which might blow your mind. okay Hummingbirds are only found in North America, South America, the Caribbean, and some of the nearer Pacific islands to South America. So we think of them as a new world family of birds. okay 30 million years ago, they were found in Europe.
Speaker: There are fossils from 30 million years ago that have been found in Germany and Poland and and France, which are clearly hummingbirds. okay So something happened to hummingbirds at some point between 30 million years ago, and i I'm going to make them a number, 5 million years ago, which meant that hummingbirds went extinct in Europe, but they still persisted Europe.
Speaker: north america and south america so so the most likely thing that caused that extinction was was climatic effect climatic changes yeah because they were clearly they were clearly doing very well in in in europe because the the fossils are relatively are relatively common now again don't get me wrong i'm not saying that climate change is okay because species can adapt and and so on it's clearly clear that anthropogenic climate change is happening much, much faster than we see in the fossil record ah or the climatic record. okay So it's happening really quickly. So species may not be able to adapt.
Speaker: The other difference is that as humans, ah we've taken over most of the planet. So there is less habitat um at a regional scale for ah for sensitive species to move to move into.
Speaker: um So ah the situation now is very, very different to the situation in in the past. Nonetheless, there is some opportunity for flexibility, for a ah resilience, if you like, within nature. But we might have to we might have to give it a give it a helping hand.
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Speaker: Talking about that helping hand, you know, a lot of my listeners are gardeners. A lot of my listeners are yeah um environmentally minded and want to leave the world in a better place. I think that there's a statistic in the UK that 4.3% of the land mass in the UK is actually garden.
Speaker: yeah how much of an impact can people have within their own space to support pollinators and support the whole web of wildlife in general they can have a a generally positive effect locally i mean you know the 4.3 or whatever whatever it is needs to be balanced against the fact that about 70 of the uk is agricultural in one way or another so so in in Purely um imp pure pure in terms of of area, it's um farmers who can have the biggest impact. And many farmers are having a really positive impact. There's some there's some great examples of regenerative farming and nature-positive farming happening across the across the country.
Speaker: um But from a local perspective, from a local perspective having a garden which is is more wildlife friendly in broad terms can can have a real positive impact for for the local environment because because Those gardens, those areas, no matter how small they are, are acting as as little population reservoirs for species um that can then move out into the into the wider countryside if there's habitat available for them. So a really good example there is cinnabar moth, ah which is a very brightly colored black and and red
Speaker: Dayflying moth. It is an important pollinator as an adult who visits a wide range of different flowers and feeds a neck and pollinates them. um it's ah Caterpillars, which are bright yellow and black striped, um ah only have but a very narrow range of of ah food plants, which are essentially the ragwort, the Sinesias. And so i try to have a little patch of ragwort in the wilder parts of my of my garden where I know that ah the Cinnabar moths can...
Speaker: can lay eggs and the caterpillars can can feed from there. But those adults themselves will disperse much further front than than than my garden. They'll they potentially fly for kilometers after they emerge.
Speaker: um So I think, and ragwort, again, is another plant. Common ragwort is doing exceptionally well this year because it's ah very well adapted to hot dry conditions.
Speaker: ah So some of the little patches of grassland close to where I i live um are becoming dominated by largely by two species, ah common ragwort and ah wild carrot as well. Both of them are doing ah doing really well at the moment. And wild carrots are really important nectar source for, again, a wide range of of different insects.
Speaker: So yeah, so individuals can can do a lot. um ah for For other kinds of wildlife, i mean you know things like making the boundaries of your garden a little bit more open, so things like hedgehogs and so on can can move about is it is important. um Feeding birds, ah using bird tables and bird feeders and so on is getting a really bad press at the moment. What's your vibe on that?
Speaker: ah I think it's, it's there there is a problem here. There is ah there is an issue where sometimes there are unintended consequences of trying to do good. yeah i mean, for me, I think why would you put out a bird feeder? It's probably the easiest and most lazy way to do it. Why don't you plant something that feeds them?
Speaker: yeah planting is is is better yeah planting is is is definitely better uh i mean the thing the thing that we like we all like and i've done it myself the thing that we like about bird feeders of course is that we get a lot of birds in one place at the same time all squabbling for uh for food and that looks great and we and we enjoy watching them. Actually, it's quite a stressful thing for those for those birds. Fighting over food resources like that is is quite stressful, which is something that we we don't take into account. But then there's also the the opportunities for... um
Speaker: ah from transmission of diseases there. exactly And we know it's had a big impact on green finch populations. I was reading recently about collared dove ah populations in Britain as well, which have ah of dropped by 40% in the last five years or so. I think it's five years. Don't don't quote me on that. Somebody needs to look that up. But they've dropped by 40%.
Speaker: very rapidly. And again, it's associated with the the diseases that have been promoted by you um by bird feeding. You mentioned before two native species, at plant species, yeah the wild carrot and common ragwort. Where do you sit on that debate between native and exotics and what we should be putting into our gardens, particularly when we're thinking about pollinators? Humans are very good at binary distinctions.
Speaker: Things are right or wrong. They're black, they're white. So when we talk about native and non-native, we've got to think about what we really mean here. So again, there's a spectrum of nativeness, if you like. There's a whole group of plants that are genuinely native to Britain in the sense that they arrived here after the last ice age yeah or possibly persisted during the ice age in the in the in the far south uh 10 000 years ago okay that's a very small group a relatively small group of of of species that persisted there there's more species that but that came over largely before the the the english channel rose okay let's say there's something like 1200 to 1500 species that fit that fit that category but then you've got a whole
Speaker: range of species which have been brought here historically prior probably to the medieval period and we refer to those as archaeophytes and the classic example there are poppies actually really not native here they were brought in by um early agriculturalists and and probably also by by romans two three four five thousand years ago possibly more they're really mediterranean species Actually, wild carrot probably fits into that category as well. So they were they were brought they were brought in because they're weed species ah that are associated with wheat and barley and and so on. So as we brought the seeds in of the plants that we wanted to grow, we brought in these weeds as well.
Speaker: Yeah. Then you've got plants which were, mean, some good tree examples here, trees that were brought in, again, probably in the medieval period, perhaps ah perhaps a little bit later, mainly for for timber, which we don't consider to be native.
Speaker: And sycamore is a classic example here. We don't think of sycamore as being a native native species. But it was native in Britain prior to the last ice age.
Speaker: It just never made it to Britain uh after after the last the last ice age so do we consider it native or or not and then you've got plants that uh were introduced much much later from from europe which we can consider to be kind of biogeographically native they belong to europe in this area yeah and and they could have so uh so i've uh up until 2024, was living in Denmark for a couple of years ah there. My wife is is Danish. And um
Speaker: There were a lot of plants growing there, which I know could grow in in Britain, ah which probably arrived there after the last last eight ice age, but they arrived in in mainland Denmark because they were able to because there's effectively a continuous land connection between southern Europe and there.
Speaker: Britain didn't didn't have that, so those plants stopped at the yeah at the French border, if you like. what is now the head the French or German border. um so ah So those I would consider to be kind of biogeographically native. And it may be many of those species that we need to think about bringing into Britain as as our climate changes in order to ah to make our habitats more resilient. Then you have a whole range of plants which clearly could never get here by by themselves, even if there was a land connection. So plants yeah from China, plants from North and South America, America, for example. So going back to your original question, why do I sit on this question of native versus non-native? I'd like to see more gardeners growing genuinely native plant species.
Speaker: I'd like to see ah gardeners also growing more species that ah from say perhaps southern southern Europe ah but which can now do very well in in British garden gardens um I'm not a purist on this by by any means um and I'm happy for people to be growing ah plants from other areas.
Speaker: I'd like to see less buddlia being grown because it's becoming incredibly invasive. Quite windy, yeah. Yeah, and that will that will get even worse again as as climate ah climate gets hotter and drier. Yeah. So I'm i'm not a purist, but but ah ah my my only restriction with this is avoid plants which are flowers which are very, very highly bred, doubled ah double flowers, for example, which don't produce any nectar or pollen and which are very colonator have yeah pollinators have problem accessing. so So I design biologically positive gardens. yeah
Speaker: And the thing that I mostly think about is beyond kind of habitat, food, blah, blah, blah. is actually flower shape and trying to get a diversity in flower shape into my designs because as we've been talking about there's lots of different pollinators that use lots of different plants um and the way that they've evolved is that they have different mouthpieces that can fit into different flowers and so i like to think of it as as opposed to only native or exotic to try and i actually i generally actually do try and sit on the native side of things, but then to also make sure that i'm hitting a vast variety of different flower shapes and leaf ah habitat and food as well, I think about.
Speaker: Yeah, and and and physical structural diversity. So um having ground flora, herbaceous species, having climbers, having shrubs, having trees, small trees or large trees as well, ah that that physical diversity is is ah is ah is good, is important too. ah um ah yeah We've we focused a lot on on flowers here, ah but one of the things I talk about in my in my first book, Pollinators and Pollination, Nature and Society,
Speaker: ah is the idea of the requirements of pollinators triangle. That actually there's there's three broad resources, if you like, that that all pollinators require.
Speaker: You know, at the top of that triangle sits the flowers. Pollinators generally need flowers in order to feed on nectar, feed on pollen or whatever. So flowers are clearly important. The other thing that they require is places to reproduce or resources for for reproduction. So that's the second ah vertex of the the of the triangle.
Speaker: And it could be bee hotels. It could be bare soil for ground-nesting bees. ah It could be a little patch of ragwort for the cinnabar moths. It could be a little patch of nettles for some of our nettle-feeding butterflies. ah So they need... Just even leaf litter and... ah Yeah, yeah, yeah. yeah Third thing that they require is, ah for want of a better term, I've called supplements. So there are other kinds of resources there. Okay.
Speaker: ah So a good example here would be, ah okay, you put in flowers and it attracts leafcutter bees. ah You put in a bee hotel, those leafcutter bees have a place to nest.
Speaker: Third thing that they require is the right kinds of leaves to be able to cut out these little semicircular discs, to then line the inside of their um their nests. So it's ah almost a kind of a supplement to the to the place to reproduce. So they need all three of those those parts of the triangle to be ah fulfilled before they'll be able to to reproduce.
Speaker: So from from a gardening point of view, Okay, focusing on the flowers, that's important, but also focus on on other things that are required for pollinators. Definitely.
Speaker: that can be about nesting uh sites or host plants could also be about you know leaving areas a little bit untidy and having more structural diversity within a within the garden water as well water is incredibly important for for pollinators uh shallow bowls of water you often find uh bees uh butterflies what's and so on feeding on on shallow water or or in a pond butterflies often coming to the edge of the ponds to as well I think too um having letting plants live out their life cycle as opposed to oh it stopped flowering let's chop it down yeah I think is a super important thing and I think that if you can get your mindset a little bit away from I need a perfect garden to yeah this is environmentally perfect I think it yeah we'll go a lot further um yeah for our pollinators and just the food web in general you know yeah and our environments
Speaker: Yeah. um And not using pesticides, reducing, you know, use of fertilizers and fungicides and and so on. We could talk about that forever. We'll just go on forever with that. um So you've now written two books.
Speaker: Yeah. What are you working on at the moment? Your last one came out. So Birds and Flowers, an intimate 50 million year relationship came out in 2024. What's next? My next book, um earlier this week, in fact, ah you're the first to hear the news. I finished the first draft of that of that book.
Speaker: And the book really centres on John Tweedy. part biographical, it's part a history of science, but it's about bringing that that up to date and talking about why it's important to and understand. So if people are interested in you, Geoff, where can people catch up with your work?
Speaker: ah Yeah, I've got a website, jeffollerton.co.uk. That's got a list of all of my papers. ah There's information about the kind of work that I do. There's also, say, a blog ah that i I update fairly fairly regularly. um Talk about not just pollin and pollination, but but environmental matters more more generally. Well, Jeff, thank you very, very, very much for your time. I really appreciate it.
Speaker: been my pleasure, Michael. It's yeah been good to chat.
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