IAP-25-074

From preferences to pollination: do hummingbirds and bees differ in how they choose flowers?

Our society and our ecosystems rely on pollinators. And so there is increasing interest in the factors that shape pollinator behaviour. Although traditional models of pollination assume that pollinators move randomly through the environment, this picture is now changing. Behavioural ecologists and movement ecologists are currently working to integrate cognitive processes, such as learning and memory, into models of pollinator movement to better predict how pollinators might behave in different environments. By including the capacity to learn and remember into our models of pollinator movements, we can gain a better understanding of how plant-pollinator communities can adapt to rapid changes in environmental conditions, such as those caused by climate change.

But there is a problem. The term “pollinator” covers a diverse range of different animal species, including invertebrate pollinators such as bees, and vertebrates such as hummingbirds. Some of these species fill quite similar ecological niches. Both bumblebees and hummingbirds, for example, primarily feed on nectar from flowers and show several similar strategies, such as forming “trapline” routes between different flowers. This can lead to these species being considered interchangeable in models of pollination. But the underlying biology of hummingbirds and bumblebees, from brains to senses to evolutionary history, is very different and these differences are potentially very important for understanding patterns of pollination. If bees and hummingbirds differ in how they decide on which flower to visit, based on differences in sensing, or learning, or memory, then this can lead to different patterns of movement thought the environment and, ultimately, different patterns of gene flow between plant communities.

Despite their clear biological differences, we know surprisingly little about whether hummingbirds and bees 1) differ in what they learn and remember about flowers: 2) differ in how what they learn and remember affects the flowers they visit, and 3) whether or not these differences lead to different patterns of movement and pollination.

The aim of this project is to directly compare insect and vertebrate pollinators by running experiments with captive bumblebees and wild hummingbirds. These experiments will provide hummingbirds and bumblebees with sets of artificial flowers that differ in various properties, such as their nectar concentration, how long they take to refill, and their spatial distribution, and test how these properties affect patterns of flower choices, how choices change as animals learn, and how choices differ between species. Using probe-tests we will examine what information, if any, animals learn about the flowers they visit, and test for differences in e.g. how long flowers are held in memory. Outside of experimental work, there will also be an opportunity to apply movement ecology models to pollinator movements, to test for differences in movement decisions between species and model the landscape-level impact of movement differences.

This project will include annual fieldwork in the Canadian Rockies, as well as experience working with bees in the laboratory, and opportunities to visit to cutting edge Centre for Research into Ecological and Environmental Modelling (CREEM) in St Andrews. Successful students will also have the opportunity to present the resulting research in international and domestic conferences.

Field experiments in the Canadian Rockies between May-July in years 1 and 2, bumblebee experiments every year in Newcastle, UK, and the opportunity to develop modelling skills by visiting CREEM in year 3.

Year 1

Year 1 will involve familiarisation with the topic through reading the literature. Initial bumblebee experiments between January-March and a field season in Canada between May-July.

Year 2

Year 2 will involve analysis of the previous season’s data, experiments with bumblebees January-March and a field season in Canada between May-July.

Year 3

Year 3 will involve analysis and modelling of the previous season’s data, including during a visit to CREEM in St Andrews, as well as a final set of experiments with bumblebees between January-March.

Year 3.5

The final 6 months will be focussed on writing up the projects, preparing publications, and submitting the final thesis.

Training in experimental design, field skills, data analysis, writing papers, presenting data in lab groups (Dr Pritchard has a regular lab meeting in Newcastle), and presenting at national and international conferences. Will also provide the opportunity to develop knowledge in behavioural ecology and movement ecology, neuroscience, comparative psychology, and pollination ecology.