Global change and urban birds
Anyone who has spent time at the University of Cape Town will know about the Red-winged Starlings Onychognathus morio on Upper Campus. These birds have developed a reputation amongst the UCT community for being sly, lunch-thieving pests and many students can recount a story of having a starling swoop past their heads on Jammie Plaza in pursuit of a Super Sandwich or some other treat. Since 2017 we have been conducting research on our favourite campus mascots, looking at how city-slicking birds such as these cope with highly variable food quality and quantity in urban environments and under increasing heat stress as Cape Town’s climate warms.
Red-winged Starlings are an excellent example of a species that has taken advantage of the opportunities offered by urban environments. While many birds avoid urban areas due to disturbance, pollution, habitat transformation and other threats that they pose, some actively exploit cities. In their natural environment, Red-winged Starlings nest on cliffs in rocky and mountainous areas, but in cities they nest on buildings. Similarly, while they would normally feed primarily on fruit and insects, they have learned that cities offer rich opportunities for scavenging on anthropogenic food.
Understanding the consequences they face as a result of replacing their natural diet with this “junk-food” is one of the aims of our research on the campus starlings. A second aim is to investigate how they cope with the lack of food on campus over weekends and holidays. Finally, we are interested in how heat stress, promoted both by the urban “heat island” effect in an already warm climate, and ongoing climate warming, interacts with urbanisation to affect the birds.
Through intensive trapping efforts in 2017 and 2018, we now have a core population of >250 individually colour-ringed starlings on campus. This has allowed us to identify that the campus starling community includes both breeding residents and a large “floating” population whose presence fluctuates with time of day. “Floater” birds ringed on campus also use areas in Rondebosch and Observatory, and gather in large numbers on parts of campus in the early evenings, for reasons which currently remain mysterious. Colour-ringing has also allowed us to monitor breeding pairs and their productivity; frequent mate changes; and toassess whether the ratio of anthropogenic to natural food fed to chicks matches that of the adult diet. The laboratory-based component of the project is being carried out in collaboration with Lund University, Sweden, as part of a bilateral project funded by the NRF and STINT (Swedish Foundation for International Cooperation in Research and Higher Education).
Activities in 2018
- The colour ringed population consists of 208 adults and 53 chicks that were ringed in 2017 and 2018.
- Through a prolonged process of habituation, we have trained several birds to jump onto a scale and “weigh themselves”, allowing us to obtain daily mass gain data and to conduct a supplementary feeding experiment conducted by Miqkayla Stofberg and Johan Jensen.
- Miqkayla Stofberg’s BSc Hons project found dietary changes on weekends and weekdays in non-breeding birds, with a near-significant knock-on effect on mass gain but surprisingly few implications for daily time-activity budgets. The manuscript is currently under review in Urban Ecosystems.
- We received funding from the NRF and STINT for a three-year joint South Africa-Sweden Research Collaboration focusing on urban avian ecology (Swedish PI: Assoc. Prof. Caroline Isaksson, Lund University). The mid-term seminar was held in De Hoop Nature Reserve in October 2018 where we worked on a review paper within the joint research team and advised joint students on their research projects.
- In collaboration with a computer science project we established an app “Starling Stalker” to record the resightings of our colour ringed birds. The app can be downloaded from: https://play.google.com/store/apps/ details?id=fitzpatrick.redwingstarlingapp
Impact of the project
Studying a resident and high-profile population of starlings that are well-known on campus has allowed us to involve the wider university community in a citizen science project, makingour research more visible and relevant. The accessibility of the project and its fieldwork has also resulted in an ideal training opportunity for younger students wanting to gain experience in behavioural research and bird observation/ handling under careful supervision. Through the help of such volunteers, the project has managed to collect a large volume of data in its first two years.
DST-NRF CoE grant; NRF-STINT South Africa-Sweden Research Collaboration; Claude Leon Foundation.
A/Prof. Arjun Amar (FIAO, UCT)
Dr Martin Andersson (MEEL, Lund University)
Dr Susan Cunningham (FIAO, UCT)
Dr Arne Hegemann (MEEL, Lund University)
A/Prof. Caroline Isaksson (MEEL, Lund University)
Dr Johan Nilsson (OIKOS office, Lund University)
Dr Petra Sumasgutner (FIAO, UCT)
Dr Robert Thomson (FIAO, UCT
Dr Hannah Watson (MEEL, Lund University)
Students: Johan Jensen (MSc, Lund); Miqkayla Stofberg (MSc, UCT); Sarah Catto (CB MSc, UCT).
Research Assistants: Dr Sally Hofmeyr; Natasha Pindral; Jessleena Suri.
Volunteers: Adam Begg, Laura Figenschou, Tsilavo Razafimanantsoa, UCT Mountain and Ski Club, Olivia Venter, Vince Ward, and many others.