Global change and urban birds
Urban environments create novel challenges and opportunities for birds. Understanding why and how some birds are able to adapt to urban landscapes, and others are not, is important to predict how ongoing urbanisation is likely to impact birds. This project aims to understand how birds in human-altered landscapes cope with the opportunities and pressures of human life.
Red-winged Starlings Onychognathus morio have developed a reputation amongst the UCT community for being sly, lunch-thieving pests. Since 2017 we have studied how these birds cope with highly variable food quality and quantity in urban environments, the stresses of sharing their space with large numbers of people, and of high summer temperatures as Cape Town’s climate warms. Early correlative work showed that adult starlings benefit from high availability of anthropogenic food, gaining more weight on weekdays than on weekends, but that chicks seem to suffer, with those experiencing many high presence human days while in the nest showing reduced growth compared to those raised during lower human presence days. Miqkayla Stofberg’s supplementary feeding experiment showed less clear morphological differences between nestlings fed different diets, but there were differences in the fatty acid profiles, with “junk food” chicks having lower omega-6, lower polyunsaturated fatty acid and higher saturated fatty acid blood profiles.
Miqkayla also assessed how urban environments might affect the starlings’ ability to manage high temperatures. She found that, while starlings respond to high temperatures by increased panting and reduced foraging time, they did not lose body mass on hot days. This result contrasts with birds in natural environments, which lose mass at high air temperatures, and suggests the abundant food resources in urban environments may buffer some of the impacts of foraging-thermoregulation trade-offs.
Jessleena Suri’s PhD focuses on how urban land cover affects bird communities in South Africa. Based at SEEC, most of her research involves occupancy modelling of SABAP2 data, and she is ground-truthing these data with finer-scale point counts around Cape Town.
Activities in 2020
- Mikayla Stofberg completed analyses of supplementary-feeding experiments and temperature-related behaviour and is currently writing up the results of both for publication.
- Before the first COVID lockdown, Taylyn Risi showed that the availability of anthropogenic food discards to Red-winged Starlings was almost five-fold greater on weekdays versus weekends and vacation days. She submitted a paper to Ostrich based on her Honours project, showing that larger starlings in better body condition occupy more heavily built-up areas on campus.
- To understand the impacts of the COVID-19 lockdown, Susie Cunningham obtained permission to return to campus in June to collect weekly body mass data. Two interesting patterns emerged: first, during the hard lockdowns over winter, starlings vacated campus in the morning, returning in the afternoon to feed in flocks on fruiting fig trees. Second, birds weighed on average 4% less during winter 2020 than in 2019 or 2018. The 2020/21 breeding season is currently in full swing on campus, and we look forward to discovering whether the lockdowns have any effect on productivity. There are currently 204 colour-ringed adults and 108 juveniles and subadults on campus. Five ringed chicks have been recruited to the breeding population, with the youngest being two years old at first breeding.
- The COVID-19 lockdown prevented Jessleena from conducting her urban bird counts, but she more than offset this loss by asking homebound bird-watchers to conduct 10-minute point counts in their gardens. More than 280 birders contributed counts, some daily for over four months! These data will be valuable to determine how gardens contribute to green space and habitat for biodiversity in urban areas, as well as assess the impact of the lockdown on bird behaviour.
- Former Fitz post-doc Petra Sumasgutner moved to the Konrad Lorenz Centre (KLF) at the University of Vienna. Together, we have built a collaboration with the KLF including Dr Thomas Bugnyer, a specialist in avian cognition. CB MSc student Varalika Jain analysed movement patterns of Ravens Corvus corax in the Austrian Alps, using data collected over the last few years, co-supervised by Petra, Thomas and Matthias Loretto. In addition, starling volunteer Mila Truter will use an experimental approach to test whether urban starlings have the cognitive capacity to recognise individual people as dangerous, neutral or beneficial and generalise this recognition across contexts for her Honours project in 2021.
- Taylyn Risi graduated with her BSc (Hons), and submitted her Honours work for publication in a special issue of Ostrich on urban birds.
- The Red-winged Starling project collaborated in the PAN-Environment Working Group, an international team of >300 authors assessing the impact of humans on the biosphere by comparing datasets collected before, during and after COVID lockdown measures.
- Jessleena Suri’s lockdown garden surveys generated considerable public awareness of her research. She contributed to a commentary on the effect of lockdown on citizen science that was published in Ostrich.
- We formed a collaboration with the Konrad Lorenz Centre, Vienna and look forward to working with them on starling cognition and ravens in the Austrian Alps.
Impact of the project
Studying the starlings on campus has allowed us to involve the wider university community in a citizen science project, making our 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.
DSI-NRF CoE grant; NRF-STINT South Africa-Sweden Research Collaboration; NRF ACESS grant.
Research team 2020
A/Prof. Arjun Amar (FIAO, UCT)
A/Prof. Res Altwegg (SEEC, UCT)
Dr Pippin Anderson (EGS, UCT)
Dr Martin Andersson (MEEL, Lund University)
Dr Thomas Bugnyer (KLF, University of Vienna)
Dr Susan Cunningham (FIAO, UCT)
Dr Arne Hegemann (MEEL, Lund University)
Dr Sally Hofmeyr (FIAO, UCT)
A/Prof. Caroline Isaksson (MEEL, Lund University)
Dr Matthias Loretto (Max Planck Institute of Animal Behaviour, Germany)
Dr Johan Nilsson (OIKOS office, Lund University)
Dr Petra Sumasgutner (KLF, University of Vienna)
Dr Robert Thomson (FIAO, UCT)
Dr Hannah Watson (MEEL, Lund University)
Students: Miqkayla Stofberg (PhD, UCT); Jessleena Suri (PhD, UCT); Varalika Jain (CB MSc, UCT); Taylyn Risi (BSc Hons, UCT)
Volunteers: Mila Truter, Chima Nwaogu, Emmanuel Adekola, Emma Swann, Carla du Toit, Rowan Hickman, Jono Plaistowe, Timothy Aikins, Anthony Lowney and many others.