Guest blog: Nectar Thieves in My Garden
Gardening often brings us closer to nature, unveiling some of the most fascinating behaviours of its inhabitants. In her new garden, long-term Pollenize patron Ruby Barter stumbled upon an intriguing phenomenon taking place right before her eyes - Nectar Robbing. As a keen observer, she embarked on a journey to uncover the secrets behind this peculiar behaviour. Join Ruby as she deciphers this captivating world of of nectar theft, revealing insights that even Charles Darwin noted in his works, and discover how a simple garden in Plymouth became a stage for nature's intricate performance…
We moved into our house in spring 2022 and were absolutely thrilled to finally have a garden of our own. I grew up in a mid-floor flat with no outdoor space and although I had no clue about gardening or what to do with this space, I did know that I wanted to create an inviting space for bees. Finally, it's my time to contribute after several years as a Pollenize patron!
I've found myself absolutely mesmerised watching several types of bees enthusiastically going about their business, and I’ll quite happily sit out an evening listening to them buzz around and watch them climb into fuchsia flowers, which seem to be their favourite of the flowers in our garden.
One evening, I noticed something interesting. Of around four bees that were visiting, none of them were crawling into the flowers like normal and were instead skirting around the top. Weird, I thought, but maybe
it's just the end of a long day.
A day or two later, I noticed that this was still happening. I wasn’t sure what I was looking at until I snapped a video to clearly see they weren't just skirting around the top of the flowers, they were punching holes and spending a few moments what looked like drinking, before moving on and doing the same on another flower.
A theory came to mind - perhaps they are drinking nectar from the top of the flower rather than crawling past the pollen like I have come to expect. But why?
Being unable to resist a good mystery and under the absolute awareness that I am neither a scientist nor a researcher, I did what any other millennial with a smart phone would. I hit Google in search of answers.
First, I learned that what the bees were doing is called Nectar Robbing. This involves animals finding a way to access the nectar of a plant “illegitimately”, without going through the normal route that leads to pollination. Charles Darwin himself wrote one of the earliest accounts describing this behaviour in bumblebees and published the observation in The Origin of Species.
Realising that before continuing I should probably figure out what kind of bees were visiting our garden the most, I scoured my video and concluded that the robber in question is most likely a worker Bombus Lucorum, or White-Tailed Bumblebee. A quick check on Wikipedia for this bee noted “because of their shorter tongues, they also developed a method of "robbing nectar."” Bingo, I’m onto something.
However, I was still confused – until very recently, bees of all types, including the white-tailed bumblebee, had been foraging “legitimately” by crawling up into the fuchsia flowers, so why the sudden change?
Initial Google searches referred to nectar dearth, a shortage in nectar and pollen. This seemed to match up with an article that references nectar robbing being more likely in times of competition and can also be an effect of bee populations being at their highest.
However, it hasn't been particularly hot and dry recently to cause death of plants and flowers. In fact, summer has felt relatively over already here in Plymouth, so although nectar dearth seems perfectly plausible if something is going on in the local environment, given how quickly this behaviour presented itself, I wondered whether there was more to this story.
This study in Argentinian fuchsias experienced the same thing as I had noticed in our garden - primarily legitimate visits followed by rapid uptake of nectar robbing for two different types of bees visiting a site.
Next, I stumbled across this study about nectar robbing in Irish fuchsias, which suggests that nectar robbing seems to be more prevalent in white tailed bumblebees and that they can learn how to do it from each other, which makes it more likely to happen in a particular site when some visitors have figured out how to do it!
Another study suggests that bees can indeed learn nectar robbing techniques from each other via “social learning”, and that they are more likely to start robbing when they have encountered flowers that have already been robbed. I found this particularly interesting as I have noticed that it’s not just the white-tailed bumblebees robbing the fuchsia, I've also spotted a Carder Bee zipping around and drinking from existing holes – a behaviour called “secondary robbing”.
Essentially, whatever the environmental causes, a few bees figured out that they could access nectar much more efficiently by robbing my fuchsia, and this behaviour spread throughout its peers and to other types of bees that visit my garden.
Bee behaviour is utterly fascinating. Sure, I’ve kept up with Pollenize’s work on local pollen data and decoding the waggle dance, but something about watching a new behaviour unfold before my very eyes just hits differently!
Have you got noticed some interesting insect behaviour in your garden? We’d love to hear from you!
