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 kills. In combination, these factors have seen the Pied Crow increase its abundance in some regions and expand its range locally. Our project investigates the expansion of this species, sometimes 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, emphasising 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. Previous Fitz research has focused on quantifying predation on tortoises and avian nest predation. Our current research builds on that research, which suggested that crows may benefit from scavenging on the carcasses of road kills. To test this idea, we are exploring whether nesting densities or breeding demography differ depending on proximity to roads of different types (tar or gravel) and their associated levels of road kills. Our research is focussed in the Hantam Karoo (Succulent Karoo), where crow densities are known to have increased substantially.
Activities in 2021
- Temitope Abisoye and Kyle Walker drove road transects throughout the Karoo collecting data on road-kill and Pied Crow abundance. This work added broad spatial data to be used in conjunction with long-term temporal data previously collected by Rona van der Merwe.
- Angela Ferguson’s MSc thesis was published in the Journal for Nature Conservation. The paper, with co-authors Tom Flower and Robert Thomson, tested the efficacy of using conditioned food aversion to decrease pied crow predation on plover nests in the Berg River IBA. The paper also provides a detailed framework for CFA trials, aimed at avoiding potential pitfalls.
Impact of the project
This research aims to build on our understanding of drivers of increasing Pied Crow abundances in certain regions of South Africa and determine the associated conservation problem, and if so, what management actions might be most effective to deal with these concerns.
DSI-NRF CoE grant; Mastercard Foundation
Research team 2021
Dr Robert Thomson (FIAO, UCT)
A/Prof. Arjun Amar (FIAO, UCT)
Rona van der Merwe
Dr Thomas Flower (FIAO, UCT / Capilano University)
Students: Temitope Abisoye (MSc, UCT)
Research Assistant: Kyle Walker