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Current Research Programmes

Understanding the ecological impacts of Pied Crows

Pied Crow Corvus albus numbers are increasing in many parts of South Africa. Recent work at the Fitz suggests that the increase in Pied Crow numbers is a result of global warming and other anthropogenic factors including the availability of nest sites on electrical infrastructure and increased food availability in urban areas and from road kill. In combination, these factors have seen the Pied Crow increase its abundance in some regions, expanding its range locally. Our project investigates the expansion of this species, now termed a ‘native invader’ species, and tries to understand what impacts these changes might have for other biodiversity.

As a generalist predator, Pied Crows may impose heavy predation pressure on a variety of prey species. Anecdotal evidence suggests that Pied Crows present a risk to threatened species, such as endangered breeding waders and range- restricted tortoises. Recently, researchers and conservation organisations have begun drawing attention to the knowledge gap with regards to the ecological impacts of Pied Crows, emphasizing the need for more studies. Indeed, there is little information about the basic life history of Pied Crows, which is an essential component for understanding the potential impacts of a predator. We aim to contribute to filling these knowledge gaps. The project specifically aims to address the impact of Pied Crows on potential prey species of conservation concern. Predation on tortoises and avian nest predation are currently being examined.

Activities in 2016

  • CB MSc student Carles Durà’s examined the extent of tortoise predation by breeding Pied Crows. Monitoring 125 active crow nests, he found evidence of tortoise predation at 26% of the nests, which were clumped in certain areas.
  • 2015 CB MSc student Angela Ferguson submitted a manuscript to Animal Conservation, demonstrating that in recently colonised areas, Pied Crows are the primary predator of wader nests. Additionally, Angela explored the use of conditioned food aversion as a management tool to mitigate crow predation of wader nests.
  • Rona van der Merwe started pilot work for a study on the ecology of Pied Crows. Rona will register for her Masters by dissertation with the Fitz in 2017.

Highlights:

  • A 2015 review paper on the impact of corvids to other bird species by CB MSc student Chrissie Madden and Arjun Amar was the most highly cited and the most downloaded paper from the journal Ibis in 2016.
  • Susie Cunningham, Arjun Amar and Chrissie Madden published an article that investigated the factors that explain the recent expansion of Pied Crows in western South Africa (Cunningham et al. 2016. Divers. Distrib).
  • Susie Cunningham and Arjun Amar also published an article in The Conversation entitled: “How climate change is causing Pied Crow numbers to soar”.
  • Grant Joseph and Colleen Seymour had an article accepted (published in early 2017) on the influence of road kill in explaining Pied Crow population increases (Joseph et al. 2017. Biol. Conserv.).

Impact of the project

This research aims to build our understanding of whether the increase in Pied Crows in certain regions of South Africa represents a conservation problem, and if so, what management actions might be most effective to deal with these concerns.

Key co-sponsors

DST-NRF CoE grant.

Research team

Dr Arjun Amar (FIAO, UCT)
Dr Susie Cunningham (FIAO, UCT)
Dr Robert Thomson (FIAO, UCT)
Dr Thomas Flower (FIAO, UCT and Simon Fraser University)
Dr Grant Joseph (FIAO, UCT and University of Venda)
Dr Colleen Seymour (FIAO, UCT and SANBI)
Dr Phoebe Barnard (SANBI)
Dr Beatriz Arroyo (CSIC, University of Castilla-La Mancha)

Students:  Carles Durà (CB MSc, UCT), Angela Ferguson (CB MSc, UCT)