Vacancies at the Bee Hotel (Ep. 14)

Understanding the relationship between different species in their natural habitats is very important when looking at biodiversity. We talk to Dr. Kit Prendergast who has been looking at the nesting success of bees in different environments and how it affects their fitness – their ability to survive and reproduce.

Kit compared the diversity and abundance of different native bee guilds, or lifestyle strategies, in both Australian bushland remnants and residential gardens. She also looks at how native bees are faring in areas with large honeybee populations. How did she do this? With her own specially designed bee hotels. 

By studying the nesting success and fitness measures of bees in different habitats, we can gain a better understanding of the intricate relationships between different species and work towards protecting our precious natural environments.

Learn more about different nesting sites bees love in Episode 2.

Dr. Kit Prendergast is a native bee ecologist who works as an ecological consultant, assisting anyone in need of a wild bee expert. She investigates the impact of honeybees on native bees and pollination networks, and the impact of urbanisation on native bees. Read her full study on bee hotels here and follow her research here.

Kit is such a fabulous promoter and supporter of bees. Her YouTube channel is buzzing, you can also follow her on Twitter, and check out her book, Creating a Haven for Native Bees.

Good to know

Another recent study Dr. Prendergast undertook involved looking a bit more closely at what native bees preferred to eat. Turns out, Australian and introduced bees prefer to visit and feed from native flowers and plants rather than exotic species. And native bees are particularly reliant on native flora. This is good information for people looking to create bee-friendly habitats in their gardens– native flowers and plants are what the bees prefer.

Transcript

[00:00:00] Feeding the bees isn’t enough, we need to help house them too. No one home fits them all, most nest in the ground, but some prefer narrow tunnels, twigs or trees. Bee hotels have become a popular way for people to provide cavity- nesting bees an instant place to live. But are they the healthiest option for bees?

I’m very pleased to introduce you to Dr. Kit Prendergast, a native bee ecologist and science communicator in Australia. Part of her work focuses on the impact of urbanization on native bees, which as you all know, is a topic very close to my heart. Today we’re going to discuss her latest research, which took a deep dive into bee hotels.

Kit, thank you for being here. Why did you decide to look at the effectiveness of bee hotels? So [00:01:00] two reasons really. One was I wanted to be able to measure the nesting success of bees in different habitats and the fitness consequences on honeybees or native bees now. Fitness in evolutionary terms is not how well you can do push ups and sit ups at the gym.

It’s your ability to survive and reproduce, and the emphasis on reproducing, because if you survive and never reproduce, your fitness is still zero. So, I’ve been looking at the impact of honeybees, which are an introduced species in Australia, and Australia is known for having introduced species devastate our wildlife. We are, you know, notable for cats and cane toads, um, decimating our wildlife.

But the honeybee has sort of gone under the radar. Because not only is it introduced species, it’s also an economically important species. So there’s that, that bit of conflict, that bit of issue there. So I really wanted to look at [00:02:00] the impact of honeybees on native bees so that we can manage honeybees in a sustainable manner.

So I’ve been looking at the association between honeybees and native bees foraging in the field, but that doesn’t necessarily show that honeybees are having fitness consequences on native bees. Native bees might be going somewhere else when there’s lots of honeybees, but still doing just as well. So I wanted to look at, in a location, are bees having fitness consequences, not reproducing as well, not making as many nests, having offspring that are smaller, skewed sex ratios.

And that’s something that you can’t know just by looking at bees foraging the field. And the great thing about bee hotels is that as a study tool, I could insert nesting tubes, take the tubes out of the bee hotels, rear them in the lab, and I could measure all these things, how many species were emerging, measuring the size of the offspring, the sex ratio.

So bee hotels were a really useful tool for [00:03:00] managing those questions, and I also wanted to look at the nesting success and fitness measures of native bees in bushland remnants versus residential gardens. So again, I’ve been looking at the diversity and abundance and different, um, guilds, which different lifestyle strategies of native bees in bushland remnants.

Um, for non Australian listeners, the bush is like natural vegetation. So we, in Perth, which is where I did the research in Western Australia, we’re lucky because we have patches of natural vegetation still scattered throughout our city, which is really beautiful but of course, these are always threatened with conflicts of development.

So I wanted to know how important were those bushland remnants compared with people’s gardens. So looking that at that, um, in the field, just looking at the native bees in these different habitats in association with honeybees, but I wanted to know the fitness consequences of native bees. [00:04:00] Now, the second reason why I wanted to look at bee hotels was also because

they are becoming very popular at, um, gardening stores. But there’s a lot of what’s called bee washing. So you might have heard of green washing before where companies, they will jump on bandwagons of people wanting to do the right thing to save the environment, but it might not necessarily actually save the environment.

You know, keeping honeybees is an example. Honeybees are a managed species and introduced species and keeping honeybees to save um, so bee biodiversity is like keeping chickens, to save bird biodiversity, it’s actually not having an impact. Um, so bee hotels, very popular, selling them at gardening stores, are they actually going to help our native bees?

If you put them up, are the native bees even going to use them? And also what are the designs that are good? So I did reading of the literature as in what’s published in [00:05:00] academic papers, um, to see what works. And then I based my bee hotel designs on this, um, to see, you know, based on best practices, do they work?

So that’s why I wanted to look at bee hotels. So many questions that I have for you on this first, let’s go back to the actual bee hotel. As you said, you designed your own with different size nesting holes. Why was this important? So there is a huge diversity of bees. I know we all get sort of told about

the honeybee, which is actually very poor representative of bee biodiversity. So it’s relatively large compared with most bees. It lives in colonies that can be managed in hives. Many native bees don’t have that social structure or that nesting habitat. So bee hotels cater to solitary bees. These are [00:06:00] bees that don’t live together, they don’t care for their offspring either.

Um, each female has her own nest, and she puts nectar and pollen into it and then seals it off. So she does the work in foraging for the offspring’s food, as well as laying the eggs, so every female is both a worker and a queen. Um, and then there’s no post laying care, so she seals up the nest. And these cavity nesting bees, in nature their nest, in little holes in wood created by wood burrowing beetles, and in urban areas as well as in agricultural areas, unfortunately, we’ve had massive habitat loss, and so these big old trees with the holes in them are often, you know, cleared, and there’s not as many, so bee hotels potentially could be a way of providing extra nesting resources, um, but then, as I mentioned, there’s not just one cavity nesting bee, there’s actually a diversity and they range in size.

So if we have, you know, just [00:07:00] one size hole, we’re going to exclude many of the other species that are bigger or smaller. But I also wanted to know what holes are used. So I trialed three different hole sizes that were sort of based on the sort of size of bees that could use them. 4mm diameter, 7mm diameter and 10mm diameter.

And this is important because if you see the ones that are sold at most shops that have drilled holes or bamboo. Most of the holes are bigger than 10 millimeters, but based on my knowledge of the size of native bees, that’s too big. Most native bees are smaller, than honeybees, um, some of them same size, some them are a bit bigger, but you’re not gonna have massive bees that nest in these cavities.

The biggest bee in the world, um, megachile pluto, that one isn’t in Australia anyway, but it nests in termite mounds. So you can see there’s a huge diversity of nesting habitats that we want to design bee hotels so that they are used by [00:08:00] native bees. Prior to my studies on bee hotels, well when I was putting them up, I found a typical bee hotel design and I published a paper on it because it wasn’t being used by native bees at all.

It had ants, wasps, and a family of lizards living in it. Which is fine, but if we’re trying to save the native bees, obviously that’s not going to do anything to them. I want to know more about the locations, the bushland and the residential areas. What did you find regarding the floral resources in each area and bee hotel usage?

Yeah, so the results from my bee hotel studies were quite similar to what I found, um, observing how many native bees there were foraging the field in that bushland remnants were better habitat. So more bee hotels were used in the bushland remnants, more offspring were produced, um, associated with the bushland remnants, but also in [00:09:00] residential gardens.

Um, native vegetation was really important. So high proportions of native vegetation. The key thing is not just how many flowers there are and that can actually reduce how well bee hotels are used because not all flowers are equal value and some are not pollinated by native bees. Um, some are pollinated by birds

or flies, some are not part of the native bees, uh, repertoire because they’re exotic plants they’re introduced from overseas and Australia especially we have like really weird cool fauna and we’re known for that and flora, you know, marsupials, uh, monotremes like platypus and echidnas. And we have, weird specialized fauna, an example is the koala who is super specialized in eucalyptus.

Because we haven’t had outside [00:10:00] influences, Australia has been isolated bio geographically from other continents for hundreds of thousands of years. So, there’s been co evolution between the plants and the animals, so plants and bees, eucalyptus, uh, Myrtaceae , the family, is also really important for native bees, not just important for koalas, but the blossoms the, the native bees love and many of them will only forage on those blossoms.

So if you have a garden full of exotic plants, like pansies and petunias and roses and rosemary, all those plants that are your typical plants that you can get at a garden store, but are introduced here in Australia, then many of those aren’t suitable for the native bees. So native plants, native vegetation are important for supporting our native bees.

And you know, it makes evolutionary sense, but still, when you go to a garden center, you don’t find that many native flowers. Did anything surprise you about the results? So, [00:11:00] I was a bit surprised in terms of the lack of an association between flower diversity and native bee diversity abundance at first because I guess like as a heuristic, diversity begets diversity, but there’s been increasingly new studies that are sort of challenging that idea and really in ecology, like the devil is in the details.

You can’t just, you know, make broad statements. You have to go into the habitat, see what’s happening, and also always think of everything in terms of evolution. That is the backbone to understanding biodiversity in every facet, and that includes conserving native bees. So, as I mentioned, the co evolution between native bees and their natural habitats and the native flowers.

Um, that is what is going to be important for them. So it makes sense when you think about it, but yeah, I guess like it’s sort of like a mantra that, you know, biodiversity begets biodiversity, but it [00:12:00] matters what type of biodiversity. So, what can you tell us about at least cavity nesting bees in Western Australia?

How are they doing? So, we don’t have good knowledge of how populations are doing, whether we’ve lost any species, whether species are declining. What we do know is that there is actually a relatively high proportion of cavity nesting bees, here. As a whole globally and as a whole in Australia,

they tend to be, you know, Not the dominant proportion of the bee fauna, but here they’re actually a lot, and that probably relates to the fact that the habitat of southwestern, eastern Australia, the natural habitat, um, lots of Maori trees, eucalyptus trees, lots of banksia, and these bees really like Fibaceae, native Fibaceae, native pea plants, and these are very abundant in the bushland remnants.

The Jacksonia, there’s like heaps of those. And so [00:13:00] at least originally, this was a very good habitat for the cavity nesting bees. And as I mentioned, we’re fortunate that there still is quite a lot of bushland left. So the cavity nesting bees are hanging on. Um, the concern though is there’s these things called sort of extinction legacy effects, where, you know, if you clear habitat and there’s fragmentation, sometimes it takes a while for species to go extinct.

You know, it could be things like inbreeding effects, which, you know, take generations to actually cause the population to decline, so it’s not like a glaciation event or a massive wildfire that just destroys everything. Sometimes these effects of extinction can take time. So it does come with that caveat, but yeah, like the Southwest of Western Australia is actually very good

for cavity nesting bees, and I was, um, amazed at how many species [00:14:00] used my bee hotels. I believe it was something like over 20 species used the bee hotels. And this is across 14 habitat, uh, 14 habitat sites that I surveyed. Um, so 14 sites. Um, over two years, so there’s probably more, and that was just how many species used the bee hotel.

So that was actually a fraction of the cavity nesting bees that were present. So that was another thing that I found was that bee hotels, they can be really useful for studying the ecology of native bees, um, as I mentioned, but you’re not going to save all the cavity nesting native bees because some of them that I saw, even abundantly in the field

didn’t want to use them. I don’t know why they just, it could be competition, but there were, there tend to be like plenty of holes that remained. So some of them just might like a particular native wood type. Like I use Jara wood, which is natural, but maybe they’re like nesting in banksia wood as I said, there’s [00:15:00] still so much that we don’t know, but yeah, there’s actually, you know, incredibly high diversity and yeah, having, you know, just

so many species present in this habitat is, you know, really amazing and shows how important it is to not neglect urban areas and just focus on, you know, other wild areas, which we should because they’re going to be the baseline, even though they’re not completely not impacted by other threats like climate change, for example, which happens everywhere.

But yeah, I found like at the moment, like there’s so much research into agriculture areas. It’s all driven by how can we improve crop production, but that’s not going to conserve native bees, because as I said, many of them are specialized, they won’t go to crops. So if you’re focusing your effort on crops, you’re not going to be conserving biodiversity.

So do you have tips for people who want to put bee hotels in their gardens? Is this something you would recommend or people should think about? Yeah, I think it’s definitely something that if done appropriately can help boost [00:16:00] native bees. Because as I mentioned, many places we have unfortunately cleared native trees

and so we’re giving them some extra opportunities to nest which is always a good thing, but we need to make sure they’re designed properly. I have a book called Creating a Haven for Native Bees which has all the information on this and I’ll also be releasing one soon that’s specifically on bee hotels.

 In general don’t have the holes bigger than 10 millimeters because you won’t get native bees using them. Put them up at like head height. They don’t go on the ground. Make sure that once the holes are evacuated, that you get like a pipe cleaner and clean it out, because there will be mites, there will be bee poop.

So what happens is the native bees, they eat all the nectar and pollen, then they do a massive dump inside their nest, because they don’t want to like… poop while they’re metamorphosing. So there’s going to be bee poop in there, and yeah, like, pooping where you’re then eating and developing isn’t a good [00:17:00] idea.

So clean out the bee hotels with a pipe cleaner. Ants are an issue, like, they, they love holes, they love nectar, so if ants go in there… again pipe cleaner, clean it out, put it somewhere else. Don’t put it anywhere near the, an ant’s nest. Don’t, yeah, buy many of the store ones because the holes are too big.

There’s like weird empty cavities, there’s wood shavings in them. There’s splinters that can damage the bee wings. They’re probably treated from exported wood from China. You know, if wood comes into a country, it has to be treated with chemicals because, you know, you don’t want pests coming into a country, so it makes sense, but not good for building bee hotels from.

Plus, you know, maybe the native bees, they like the smell of the native wood rather than some introduced wood. So it’s, yeah, it’s really easy to make your own as well. As I mentioned, block of native wood, drill holes in it. I’ve also had success with bamboo. Make sure the holes are deep too, um, 10 centimeters, about 10 centimeters deep.

If they’re [00:18:00] shorter they might be entirely parasitoid .

parasitized by a parasitoid wasp um of native bees. So if you have it longer, there’s gonna be probably a greater chance that the ones at the back will be saved from paratisism.

Try not to keep honey bees in your backyard because it’s not helping biodiversity, it could be competing with the native bee. Do you have a favorite bee? Oh my God, I love so many. I’ll talk about two of my favorites. Because I have tattoos of bees, um, probably adding to them. Oh, I’ll talk about three. I’m so bad at deciding.

Okay, so the first one is Amigula Dorsoni. This bee was sort of my gateway into native bees. I learnt about it in undergrad based on its alternative mating tactics. And then I got an opportunity to go up and study it with a researcher from Arizona, and he’s sort of like an amazing [00:19:00] bee guru. And I had an amazing time.

And then when I finished my PhD as like a celebratory thing, I got a tattoo of them on my back. And then another one that I really love is megachile aurifrons . The megachile are the main ones that use bee hotels and I just love their name firstly, like megachile, that’s cool. I first published a paper on a species, which was then re classified to a genus all on its own, Rosinapis.

But yeah, the megachile, they’re, they’re just really cute. Like they, they’re cute. Again, they have really interesting mating habits. And after my PhD, my first big project was I led a project where I installed a thousand bee hotels in areas that had been affected by fire to see if providing extra nesting habitat could help the native bees colonize and establish in these post fire habitats.

And it was like, it’s something that hasn’t been done before. So I was like, oh, you know, it might not work. [00:20:00] Sorry to my dad who spent so many, so much time filming bee hotels for me, um, but it did, it was like, I, every single one was occupied. Some of them, every single hole was occupied. They were occupied more, far more than the ones in my urban studies, which suggests that either there’s more bees in these post-fire habitats, which I could rule out because I was also observing how many native bees there were.

It was a fact that there was a shortage of bee nesting habitats. Once the fire had gone through, as makes sense, and so yes, putting these up allowed bees a better chance of recovery. So that was really, really great. So I decided to get a tattoo of megachile and I chose a megachile that uses the bee hotels a lot and it’s also freaking amazing because females have red eyes.

 Bright red eyes, and the males have two tone red and green eyes, but I decided to get one of the female because they’re the ones who use the bee hotels. Yeah, so that’s my second favorite [00:21:00] native bee, and the third one, I described it. It’s not every day you get to describe a new species. It’s called Leoproptus zephyr. And I

described it after my dog. Her name is Zephyr. So the bee is in the genus leoproptus, the species is Zephyr. And, um, I named it after my dog because she is very beautiful and very special to me and she was with me throughout my whole PhD journey. So I really wanted to, you know, commemorate her for life. Like that species is never going to, unless it goes extinct, which I really hope not because it’s actually super rare and super specialized and has no legislative protection.

But yeah, yeah, commemorating her by describing a new species after her. That is beautiful. I love the dog connection. I have so many questions though now. First, going back to when you installed the bee hotels in the areas affected by [00:22:00] forest fires, you had great results with the bees living in the hotels.

What were they foraging on? Western Australia is, uh, sort of a fire prone country. So the good thing is that unlike, say, in Tasmania, where I would love to replicate this study to see if I get the same results, fires being part of the landscape, not to the same frequency and extent that we’re having now. So that’s the issue.

But the plants have evolved to spring back quite readily after fires. So it’s called, Bossiaea, a native pea comes back quite quickly after the fires and our eucylupts , because they’re quite tall, and these fires weren’t as devastating as the fires on the east coast of Australia, the like, upper canopies of what’s called, um, marri, which is ​Corymbia calophylla endemic to Southwest, Western Australia makes

Amazing honey, um, called red gum [00:23:00] honey. It’s got really good floral resources for native bees, many native bees forage on it. I’m working on a paper soon to be submitted where I actually say how many species have been recorded on it, and it’s 80 species, which is amazing. Yeah, a lot of species. So yeah, a really important resource.

So the native bees were foraging on these resources that were able to either survive or spring back after the fires. So that’s the important thing. So there are some people who are doing some very bad things and what they’re doing is they’re putting bee hotels up in good habitats. The native bees are colonizing the bee hotels and they’re taking the bee hotels from the good habitats and putting them into post fire habitats.

Now, this could be a terrible idea. If the post fire habitats aren’t regenerating, then you’re essentially putting native bees into these habitats just to die. So that’s why I put in empty bee [00:24:00] hotels. If the native bees didn’t use them, that’s evidence that the habitat is bad and the bees aren’t recolonizing.

So you’re also potentially depleting native bees from good populations by, you know, taking out an entire next generation, putting them somewhere else and moving genes around. Very bad idea. So if anyone’s thinking of doing that, please don’t. So bee hotels, putting them in there, it will tell you if native bees can colonize the area.

Putting bee hotels with bees already in them into another place is not a good idea. You could do some damage there.. Is there any reason or any situation in which relocating native bees from one area to another would be a good idea? Yeah, if an area is going to be cleared, like, there’s no chance of it not being protected. If it’s going to be mined, like mining, Western Australia is known for its mining, alas.

And unfortunately, lots of the… [00:25:00] Money that’s able to fund conservation work is due to mining or mining offsets. So like they clear a habitat it’s like they have to put money into conservation to offset that. Yeah, if you’re mining something restoration takes many years. So better to have the native bees go into the bee hotels and put them in the safe habitat So there that way you’re taking native bees from somewhere that’s bad or that’s gonna be bad to a good place rather than taking them from a good place to a potentially bad place.

So yeah. If Habitat is gonna be cleared. What do you believe is the biggest threat to native bees and what can we do to help? Yeah. Biggest threat? Well, habitat destruction, loss of natural habitat is the biggest threat and we can help that by, you know, asking councils, no, we don’t want to widen this road, or we don’t want to have the verge cleared, or we prefer to have our lot and, you know, stay the same size with a big [00:26:00] yard full of native vegetation rather than subdivides where you’ve got apartments stuck together.

And, you know, again, advising, asking councils, can you get a native bee scientist to see what flowers the native bees in your area like so that we can have evidence based planting guides for natural areas. Yeah, native bees need to be on the radar more and this is an issue facing invertebrates in general, but yeah, we need to conserve native bee biodiversity and this involves knowing what the diversity is.

What the species are and actually including them in protection. I couldn’t agree more. Thank you so much. Thanks for inviting me. Raising awareness of native bees is so important on so many levels. Thanks again to Dr. Kit Prendergast for joining us today and thank you for listening. Be sure to visit the [00:27:00] website, thebeesknees.

website to read more about Kit’s research into bee hotels, a link to the book she mentioned, and more. See you again in September, and until then, keep buzzing.