Understanding how urbanisation impacts diet and fitness of a well-known garden bird, the Blue Tit

Overview

Urbanisation has transformed habitats across much of the world, leading to altered local environmental conditions, increased pollution, changes in community composition, and altered food availability. Some species are able to exploit these habitats (“winnersâ€), while some are able to cope or adjust to a degree (“adaptersâ€), and others are forced to either disperse away or suffer local population extinction (“avoidersâ€). Overall, a general pattern of lower species richness in urban areas has emerged. It is becoming increasingly important to understand what factors influence species’ success (or failure) in these ubiquitous environments in order to maintain biodiversity in a rapidly urbanising world.

The widely known garden bird, the blue tit (Cyanistes caeruleus), may initially appear to be a winner at successfully exploiting urban environments. Indeed, adult birds may benefit from warmer winter temperatures and supplemental food resources provided by humans. However, during the breeding season, cities may actually become “ecological trapsâ€ for blue tits because they have limited availability of fat and protein-rich caterpillars required in the specialist diets of rapidly growing chicks. Several studies have demonstrated that blue tits breeding in cities actually have lower reproductive success than birds breeding in forested sites, yet the causes of this pattern remain unclear. Previous studies have suggested that there are fewer caterpillars in cities, and that parents have to fly further to find them, so they may switch to provisioning young with lower quality but easier-to-find food resources, potentially including anthropogenic foods. Parents might also be in worse condition due to pollutants or disease. These factors might all influence winter survival of adults as well as their reproductive success in the following summer.

In this project, the student will work closely with collaborators from Glasgow University at long-term ecological research sites along an urbanisation gradient from the heart of urban Glasgow to an undisturbed oak forested research station. The goals of this study are to examine:

1) How the diets of nestling blue tits change along the urbanisation gradient;
2) How the diets and condition of parents varies along the gradient and throughout the year;
3) Whether changing diets along the gradient predict survival and reproductive success.

Because of the previous difficulty in analysing diets in high resolution (e.g., diet items fed to chicks on video can only be crudely classified as caterpillar vs. non-caterpillar), hypotheses about the impacts of food availability on urban species’ reproductive success have largely been unexplored, and diet may provide a missing link in understanding species’ persistence and extirpation in cities.

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Image Captions

Blue tit with a caterpillar. Photo by Mark Philpott, under the Creative Commons license (CC BY-NC 2.0). https://www.flickr.com/photos/fftang/5723077523/sizes/l/

Methodology

This project will provide the student comprehensive experience in both the field and the lab. In collaboration with Dr. Davide Dominoni, (s)he will participate in fieldwork in Scotland. This will involve mist netting birds, collecting morphometric data, conducting telemetry to investigate foraging effort, and video surveillance to roughly document food provisioned to chicks. Video and behavioural data will be analysed using sophisticated statistical models. In the lab, the student will conduct diet DNA metabarcoding of samples collected from both the parents and the chicks. In this approach, DNA from diet items is extracted from faecal samples of the birds, and then sequenced on a next-generation, high throughput platform, to obtain the sequences of hundreds of diet items from up to 200 birds simultaneously. This will provide high-resolution detail of the diets consumed by the birds both during the breeding season and throughout the year. Powerful bioinformatics approaches will identify the taxonomy of the diet items and potentially information about abundance, and then statistical analyses will be carried out to identify significant differences between sites and through time.

Project Timeline

Year 1

Fieldwork (primarily spring breeding season but also at intervals throughout the year), metabarcoding lab work, preliminary bioinformatics

Year 2

Fieldwork, metabarcoding lab work, attendance of a workshop on metabarcoding approaches for ecology, including bioinformatics/programming, and data analysis; complete bioinformatics and continue on data analysis, manuscript preparation

Year 3

Data analysis, manuscript preparation, international scientific meeting attendance

Year 3.5

Finalize manuscripts and submit/defend thesis

Training
& Skills

Through this project the student will develop many highly desired and transferrable skills. From Dr Davide Dominoni in Glasgow, the student will gain experience planning a field season, skills in ethical handling and use of animals in research, current technologies for monitoring animal behaviour and movements, and training in advanced statistical analyses. The Welch lab at Durham is part of a large, vibrant Molecular Ecology group using genetic techniques to study the ecology and evolution of animals and plants. Situated within the larger Ecology, Evolution, and Environment research theme, the student will have the opportunity to attend seminars from leading researchers and take part in reading and discussion groups. In the lab, he or she will learn general skills (e.g. preparing solutions) as well as new cutting-edge DNA sequencing skills that will be important for a research career in ecological and evolutionary genetics, but also provide a strong foundation for careers in environmental testing, molecular biology, agricultural biotechnology, and medical testing/research. Numeracy and computer programming, two widely desired traits, will be well developed through use of sophisticated bioinformatics approaches and implementation of rigorous statistical analyses. Scientific writing and attendance at professional meetings will aid in development of key networking and communication skills. Additionally, organisation and time management skills necessary for this project are widely applicable in all industries.

References & further reading

1) Pollock et al. (2017) Integrated behavioural and stable isotope data reveal altered diet linked to low breeding success in urban-dwelling blue tits (Cyanistes caeruleus). Scientific Reports 7:5014
2) Narango et al. (2018) Nonnative plants reduce population growth of an insectivorous bird. PNAS 115:11549-11554
3) Murray et al. (2015) Poor health is associated with use of anthropogenic resources in an urban carnivore. Proceedings of the Royal Society B 282: 20150009
4) Sumasgutner et al. (2014) Hard times in the city – attractive nest sites but insufficient food supply lead to low reproduction rates in a bird of prey. Frontiers in Zoology 11:48
5) Jones et al. (2008) Feeding birds in our towns and cities: A global research opportunity. Journal of Avian Biology 39:265-271
6) Tremblay et al. (2003) Variation in Blue Tit breeding performance across gradients in habitat richness. Ecology 84:3033-3043
7) Deiner et al. (2017) Environmental DNA metabarcoding: Transforming how we survey animal and plant communities Molecular Ecology 26:5872-5895

Further Information

This project is in competition with others for funding, and success will depend on the quality of applicants, relative to those for competing projects.

Funding includes tuition fee waiver for Durham University, a competitive stipend, and research support.

To express interest in applying, or for further information, you should contact Dr. Andreanna Welch at a.j.welch@durham.ac.uk by early January 2020. In your email include: 1) a few sentences detailing your reasons for applying and how your experiences fit with the project, 2) your CV with marks earned for previous degrees and 3) contact information for at least two references. Only the best applicants will be asked to submit a full application, including two reference letters, by 16:00 on the 10th of January 2020.

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