flowers – Cabot Institute for the Environment blog

Migration, mobilities and the ecological context

Posted on May 10, 2022April 16, 2023 by janet.crompton

In this special blog series, Migration Mobilities Bristol (MMB) and the Cabot Institute for the Environment bring together researchers from across the University of Bristol to explore connections between movement and the environment from a multi-disciplinary perspective. Their diverse approaches highlight the importance of developing frames that incorporate both migration and environment, and in so doing benefit our understandings of both.

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Migration can make you happy. When I see the first swifts arrive in the spring, I stop in my tracks and smile broadly at all and everyone. I have to restrain myself from telling people walking down the street that ‘they’ are back. Swifts are one of the wonders of the world – they make Concorde look clunky, they hurtle down streets in towns screaming wildly at dusk seemingly just for the fun of it, and scientists have calculated that the distance they fly over their lifetime is equivalent to flying to the moon and back seven times!

Dahlia (Bishop of Llandaff). Image credit: Jane Memmott

Migratory species like swifts have two homes and they are generally well regarded in both places. It’s a bit more touch and go whether alien species are welcome or not, and highly context dependent. For example, we deliberately introduce species from all around the world into our gardens without qualm – looking out the window onto my front garden, I’ve got honey bush and pineapple lilies from South Africa, Dahlias from Mexico, a Hebe from New Zealand, devil’s tobacco from Chile and foxgloves from seed collected down the road! In contrast, my local nature reserves are doing their best to remove Rhododendron, Cotoneaster and Himalayan balsam.

Context really is key here. Thus, gardens are grown for colour, relaxation, fruit, vegetables, and art (and I consider gardening as much of an art as a science) and they are highly managed and artificial habitats. In fact, they are increasingly considered as outdoor rooms in the media, and no one worries what countries their botanical furniture is from. In contrast, nature reserves are usually more natural settings where we want to capture natural patterns and processes, so there is an expectation that the species present should be native. And there is good evidence that while most alien species are harmless, some species (approximately 1%) can be very damaging to the environment and the economy.

Honey bush leaves (Melianthus major). Image credit: Jane Memmott

Migration is about mobility, and mobility is a key part of the scientific process. Thus, universities are ecosystems which provide intellectual homes to academics from all over the world. My own department is home to scientists from Africa, Germany, Brazil, Switzerland, Brazil, Italy and China and those are just the people I’ve bumped into over the last few days. COVID has put a bit of a spanner in the works on the mobility front, but mobility is so key to business that academics have quickly found other ways to be mobile. For example, in my own research group, we have been running a large project in a remote part of Nepal entirely by Zoom for the last two years. But, by dint of the internet and some incredible UK staff and amazing project partners in Nepal, we have trained field staff in ten remote villages in the Himalayas to collect diet data for both bees and villagers, using protocols that would have been very new to them. The data is then uploaded by the field staff to the internet and arrives on the computers the other side of the world as if by magic.

Mobility is such a large part of a scientist’s life that when it goes wrong it can feel shocking. I’ve had two encounters with mobility of scientists being blocked, one involving myself, another a visiting scientist. Mine was, I suspect, a straightforward random immigration check, but it did leave me rather shaken. I was travelling to Canada for the first time and got taken out of the queue and then grilled for 30 minutes on the nature of my visit. I was giving a plenary talk at a conference and had fortunately remembered to print out my letter of invitation. Unfortunately, I hadn’t actually read it for six months and so I probably did sound a bit suspicious. They did eventually let me in and it was an excellent trip thereafter. The second time was when a restoration ecologist from Latin America, who was visiting my research group for six months, went to Spain with his family for a weekend and upon return his whole family was issued with deportation papers. There is something deeply shocking about seeing the hostile environment process in action, especially when mobility is simply part of normal academic interchange. After some high-level work by an international lawyer this too was fixed. Restoration ecology is much more of a long-term process, but the restoration of mobility was much faster in this instance, if a lot more stressful.

Swift (Apus apus). Image credit: Wikimedia Commons.

Migration and mobility are everyday events in the environment. They can be natural such as the return of swifts each year, or they can be assisted such as the reintroduction programmes for species that have become extinct in the UK. One of the biggest reintroduction success stories is the red kite, a bird that you are almost guaranteed to see now if you drive down the M4 motorway or look out of the train window from Didcot to London. These are big and very beautiful predatory birds – imagine a paprika coloured swallow with a 6ft wingspan! My last few Saturdays have been spent driving from Bristol to a hospital in Hampshire to visit a sick relative and one of the things that has made this less stressful is counting the red kites along the motorway. Last Saturday was a 12-kite day, my highest count yet.

To end, migration, mobility and the environment are inextricably linked. There is both natural and human assisted movement of species in the environment. Species can be both welcome and unwelcome depending on the context. It’s complicated, but it’s the everyday bread and butter of ecologists around the world. With alien plants bringing colour and bizazz to our gardens and swifts bringing happiness as they return to their second homes in the UK, there is a lot to like about migration and mobility in the environment.

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This blog is written by Cabot Institute for the Environment member, Jane Memmott, Professor of Community Ecology in the School of Biological Sciences, University of Bristol. Her research interests include pollination ecology, invasion ecology, biological control and restoration ecology. In each case she considers how ecological networks can be used as a tool to answer environmental questions.

Professor Jane Memmott

Urban gardens are crucial food sources for pollinators – here’s what to plant for every season

Posted on January 26, 2022March 29, 2023 by janet.crompton

A bumblebee visits a blooming honeysuckle plant.
Sidorova Mariya | Shutterstock

Pollinators are struggling to survive in the countryside, where flower-rich meadows, hedges and fields have been replaced by green monocultures, the result of modern industrialised farming. Yet an unlikely refuge could come in the form of city gardens.

Research has shown how the havens that urban gardeners create provide plentiful nectar, the energy-rich sugar solution that pollinators harvest from flowers to keep themselves flying.

In a city, flying insects like bees, butterflies and hoverflies, can flit from one garden to the next and by doing so ensure they find food whenever they need it.
These urban gardens produce some 85% of the nectar found in a city. Countryside nectar supplies, by contrast, have declined by one-third in Britain since the 1930s.

Our new research has found that this urban food supply for pollinators is also more diverse and continuous throughout the year than in farmland. Everyone with a garden, allotment or even a window box can create their own haven for pollinators. Here are tips on what to plant for each season.

Three people in wellington boots work on raised beds in a garden. — Community gardens, allotments, even window boxes can sustain pollinators throughout the year.
KOTOIMAGES | Shutterstock

What to plant in spring

The first queen bumblebees emerge from winter hibernation in February and March. They need food straight away.

At this time of year nectar-rich plants are vital energy sources for warming up cold flight muscles, with pollen providing the necessary protein for egg laying and larval growth. In early spring much of the countryside is still bleak and inhospitable.

Gardeners can help by planting borders of hellebore, Pulmonaria and grape hyacinth. Trees and shrubs such as willow, cherry and flowering currant are also fantastic for packing a lot of food into a small space.

A bee on a willow flower — Willow in bloom.
Ira Kalinicheva | Shutterstock

What to plant in summer

In late spring and early summer, pollinators have more food available – but there is also more competition for it. So it is crucial to ensure you have a diverse array of different flowering plants. This will guarantee there is attractive and accessible food to suit a wide range of insects and provide them with nutritionally balanced diets.

A great assortment of plants, including honeysuckle, Campanula and lavender, can provide floral resources in summer. Mowing the lawn a little less often will help too, giving the chance for important so-called weeds, such as clover and dandelion, to bloom.

Ivy in bloom with a red admiral.
Seepix | Shutterstock

What to plant in autumn

By late summer and autumn there are fewer species still flowering in gardens. A handful dominate the nectar supplies, particularly Fuchsia, Salvia and Crocosmia.

For many pollinators, however, these flowers are entirely useless. Their nectar is hidden away down a tube, only accessible to insects with long tongues, such as the garden bumblebee.

This means solitary bees and hoverflies may need to find other sources of food. The gardener can help by prioritising open and accessible flowers. Opt for species such as ivy, Sedum, Echinacea and oregano.

What to plant in winter

Few pollinators are still active in winter. Most species die off leaving the next generation behind as eggs, larvae or pupae.

But bumblebees and honeybees remain in flight, taking advantage of the warmer climate and winter flowers that cities can provide. By vibrating their wings, bumblebees can warm up to forage in temperatures barely exceeding freezing point, but they need a lot of energy-rich nectar to do so. If you want to attract bees into your garden during the winter some of the best options are Mahonia, sweet box, winter honeysuckle and the strawberry tree.

Yellow Mahonia on a frosty morning. — Mahonia on a frosty morning.
Sally Wallis | Shutterstock

Urban gardens are small and numerous, with hundreds or even thousands packed into a single square kilometre of a residential neighbourhood. Each gardener is different, with individual preferences of what to plant, how regularly to mow the lawn and even how to decide what constitutes a weed.

This results in an enormous variation from garden to garden in the quantity of nectar, the timing of its production and the types of flowers producing it. But there is always room for improvement. Some gardens provide pollinators with hundreds of times less nectar than others.

So keep yours well stocked with nectar and free from toxic pesticides. You’ll be amazed by the impact you can have.

This blog is written by Caboteers Nicholas Tew, PhD Candidate in Community Ecology, University of Bristol; Jane Memmott, Professor of Ecology, University of Bristol, and Katherine Baldock, Senior Lecturer in Ecology, Northumbria University, Newcastle

This article is republished from The Conversation under a Creative Commons license. Read the original article.

‘Back in buzziness’

Posted on August 18, 2016April 6, 2023 by janet.crompton

Awareness of the plight of bees and other insect pollinators, both across the UK and globally, has grown in recent years. One of the main contributing factors is habitat loss and the decline in flowers that provide nectar and pollen, which are vital resources for pollinators. This was highlighted by research conducted by Mathilde Baude and colleagues from the University of Bristol, which featured on the cover of the journal Nature this February (Baude et al., 2016).

Image courtesy of Nature.

Facilitated by generous support from the Alumni Foundation and a Grow For It Award grant, a group of students at the University of Bristol initiated a project to address this issue. Using recycled scaffolding planks from the Bristol Wood Recycling Project, they constructed two raised beds to be sown with a highly diverse mixture of native wildflowers.

Raised beds created at the University of Bristol behind the Biomedical Sciences building using recycled scaffolding planks and native wildflowers.

Get Bristol Buzzing assisted in selecting the seed mix, which is made up of annuals and perennials of thirty-seven species (including some rare species). When complete, the planters will create over 30 m2 of rich urban pollinator habitat.

In June 2016, student volunteers prepared one of the planters with topsoil and recycled construction material from the local area. The meadow, which occupies a previously open concrete space behind the Biomedical Sciences building, is in now in bloom and buzzing with bees.

Next year, a group of student volunteers will prepare the remaining bed, ready for the summer. There are also plans to organise other events and workshops to continue to raise awareness amongst students, while sharing information on practical ways in which individuals can contribute to creating more pollinator habitat. Student volunteers will also be responsible for the ongoing maintenance of the beds.

The diverse meadows not only create habitat for pollinators and other insects, but also provide food for seed-eating birds and shelter for small animals. As well as promoting biodiversity within the campus, the meadows are sure to contribute positively to the wellbeing of staff, students and members of the public who use this space.

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This blog is written by Harry Wells, from the Bristol Hub, a student-led group offering practical volunteering, skilled placements, project incubation and events to help you shape a better world.

In defence of wasps: why squashing them comes with a sting in the tale

Posted on July 25, 2016April 6, 2023 by janet.crompton

Image credit: Trounce

They are one of the most unwelcome signs of summer. Buzzing through beer gardens, attacking innocent picnics, wasps arrive ominously with a sting in their tails. Universally disliked, they are swatted, trapped and cursed. But would a wasp-free world really be a better place?

Despite their poor public image, wasps are incredibly important for the world’s economy and ecosystems. Without them, the planet would be pest-ridden to biblical proportions, with much reduced biodiversity. They are a natural asset of a world dominated by humans, providing us with free services that contribute to our economy, society and ecology.

Wasps, as we know, turn up everywhere. More than 110,000 species have been identified, and it is estimated there are still another 100,000 waiting to be discovered. One recent study described 186 new wasp species in one small corner of Costa Rican rainforest alone. In contrast there are only around 5,400 species of mammals, and 14,000 recorded species of ant.

This huge and diverse assemblage belongs to the order Hymenoptera and is divided into two groups, the Parasitica and the Aculeata. Almost 80,000 species of wasps belong to the Parasitica group, which lay their eggs in or on their prey or plants using elongated tubular organs called ovipositors. The remaining 33,000 species are Aculeates, most of which are predators, and the ones whose ovipositors have been modified through evolution to form a sting.

Both parasitic and predatory wasps have a massive impact on the abundance of arthropods, the largest phylum in the animal kingdom, which includes spiders, mites, insects, and centipedes. They are right at the top of the invertebrate food chain. Through the regulation of both carnivorous and plant-feeding arthropod populations, wasps protect lower invertebrate species and plants. This regulation of populations is arguably their most important role, both ecologically and economically.

Although the majority of wasps lead solitary lives, it is the 1,000 or so species of social wasps which make the biggest impression on insect populations. Social wasp queens share their nests with thousands of offspring workers, who raise upwards of 10,000 sibling larvae during the colony cycle. This means a single nest provides a whopping bang for buck in terms of ecosystem services, killing vast numbers of spiders, millipedes and crop-devouring insects.

Pest control. shutterstock

Many social wasps are generalist predators too, which means they control populations of a wide range of species, but rarely wipe any single species out. This makes them an extremely useful, minimising the need for toxic pesticides, but unlikely to threaten prey biodiversity. It is not yet possible to accurately quantify their huge economic value in this regard, but their diet of agricultural pests such as caterpillars, aphids and whiteflies makes a massive contribution to global food security.

Wasps also play a crucial role in ecosystems as specialist pollinators. The relationship between figs and fig wasps is arguably the most interdependent pollination symbiosis known to man. Without one another, neither the fig nor fig wasp can complete their life-cycle – a textbook example of co-evolution which is estimated to have been ongoing for at least 60m years. Figs are keystone species in tropical regions worldwide – their fruit supports the diets of at least 1,274 mammals and birds. The extinction of fig wasps would therefore be catastrophic in tropical ecosystems.

The birds and the bees … and the wasp

Almost 100 species of orchids are solely reliant on the action of wasps for pollination. The plants mimic the appearance and chemical profile of female wasps, tricking males into attempting to mate with them, so that as the male wasps attempt to copulate with the flower they are loaded with pollen which is then transferred to the next male-seducing orchid. Without the wasp, these orchids would be extinct.

Working wasp. Shutterstock

Wasps also function as generalist pollinators, inadvertently transferring pollen between flowers they visit for nectar collection. One type even provide their larvae with pollen instead of insect prey. These “pollen-wasps” are considered to perform the same ecological roles as bees, pollinating a diverse array of plants. Unfortunately, while bees are credited with contributing at least €100 billion a year to the global economy through their acts of pollination, the works of wasps in the same sector is often ignored.

Even the wasps’ sting could have a positive impact on the human population. Medical researchers are exploring the potential use of biologically active molecules found within wasp venom for cancer therapy. A chemical found in the venom of the tropical social wasp Polybia paulista, has been shown to selectively destroy various types of cancerous cells.

Since they protect our crops, make ecosystems thrive, sustain fruit and flowers, and might help us fight disease, perhaps we should appreciate the wonderful work of wasps before we next swipe at them with a rolled up newspaper. They may be a nuisance on a sunny afternoon – but a world without wasps would be an ecological and economic disaster.

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This blog is written by Cabot Institute member, Seirian Sumner, a Senior Lecturer in Behavioural Biology, University of Bristol and Ryan Brock, MRes candidate, University of Bristol. This article was originally published on The Conversation. Read the original article.