Coevolution is the process by which two or more species influence each other’s evolution. Brood-parasitic birds, the cheats of the bird world, give us an ideal opportunity to study coevolution in the wild. Coevolutionary “arms races” arise when hosts evolve defences such as rejecting parasitic eggs, which imposes natural selection for parasitic counter-adaptations such as mimicry of host eggs, and in turn for ever more sophisticated defences from hosts. Three long-term projects in Zambia, the Western Cape of South Africa and Finland, address different aspects of this fascinating model system for coevolution.

Claire Spottiswoode and Gabriel Jamie’s team works on a variety of brood-parasitic systems in Zambia, focusing mainly on three broad questions. First, how do interactions between species generate diversity among individuals? Specifically, how do biological arms races between hosts and parasites shape phenotypic diversity in both parties? For example, parasites diversify to mimic multiple hosts, and in response hosts sometimes diversify with defensive adaptations to foil mimicry, such as visual 'signatures' of identity. Second, how is specialisation to different coevolutionary partners maintained? The genetic basis of signature-forgery arms races is almost entirely unknown. In collaboration with Prof. Michael Sorenson (Boston University), we are using genomic approaches to ask how specialised adaptations to different host species (mimicry of host eggs) are maintained within a single parasitic species (e.g. Cuckoo Finches Anomalospiza imberbis and Greater Honeyguides Indicator indicator) in the absence of parasite speciation. We are also interested in the genetic basis of host defences, and whether convergent genetic mechanisms have evolved in their parasitic mimics. Third, what is the role of phenotypic plasticity (such as developmental differences and learning) in coevolution, and how might such plasticity facilitate exploitation of new host species in the absence of appropriate genetic adaptations? We are addressing this question for indigobirds, whydahs and honeyguides

Fitz Research Associate Jessie Walton has been studying Brown-backed Honeybirds Prodotiscus regulus, which parasitise Karoo Prinias Prinia maculosa at a high rate in the Bot River area of the Western Cape. Brown-backed Honeybirds have blue eggs, highly unusual in piciform birds, broadly mimic the blue eggs of their hosts. Moreover, up to three honeybird chicks are raised in the same host nest, despite killing host young with their bill hooks. How honeybirds escape being killed by their nestmates remains an intriguing mystery.

Robert Thomson’s team works in Finland, where their research focuses on how host pairs of Common Redstarts Phoenicurus phoenicurus can decrease the chance of a Common Cuckoo Cuculus canorus parasitising their nest. Hosts that are able to avoid parasites decrease the fitness costs of parasitism; the earlier that avoidance occurs during the breeding cycle, the lower the cost. Therefore, host adaptations before egg laying should be especially beneficial. The Finnish project investigates the redstart’s frontline defences (nest site choice, habitat selection, nest building decisions) and the cuckoo’s counter-adaptations, including prospecting and laying strategies, which have received little attention to date. Redstarts are the only regular cuckoo host that breed in cavities, which makes it difficult for female cuckoos to lay eggs and for their newly-hatched chicks to evict host eggs/chicks. This project also studies whether cuckoo females use behaviour and physiology to enhance the manipulative signals that cuckoo nestlings use to extract as much care as possible from their foster parents

Activities in 2024

  • We carried out two seasons of fieldwork in Zambia: rainy season fieldwork in January–March on cuckoo finches and their hosts (Tanmay Dixit), and dry season fieldwork in September–November (Jess Lund and Mairenn Attwood) on Greater Indicator indicator and Lesser I. minor Honeyguides and African cuckoos Cuculus gularis and their hosts, together with our local field team led by Collins Moya, Silky Hamama and Onest Siakwasia.
  • Gabriel Jamie conducted fieldwork in Angola (Jan–Feb) with Michael Mills on several poorly known cisticola taxa. Gabriel also conducted whole-genome sequencing on a wide range of cisticolid species collected during fieldwork in Nigeria, DRC, Angola, Zambia and South Africa over the past several years, to track the inheritance and diversification of anti-parasitic egg signatures across the cisticola family.
  • Maggie Mwale began the process of curating the remarkable ornithological collection of Zambian birds made by John Colebrook-Robjent, now housed at Livingstone Museum, and supported by the new Max Planck–UCT Centre for Behaviour and Coevolution. Maggie is Curator of Ornithology at the Livingstone Museum as well as a recent CB MSc graduate at the Fitz.
  • Joel Radue started his MSc studies on the ecology and evolution of fire-dependence in birds, with a special focus on Bronze-winged Coursers Rhinoptilus chalcopterus studied at our long-term study site in Zambia, where, as well as brood parasites, we study the thermal ecology of ground-nesting birds. Joel is supervised by Claire Spottiswoode, Eunbi Kwon and Sally Archibald.

Highlights

  • Project co-leader, Gabriel Jamie, was appointed as a Lecturer at the Fitz, supported by the Max Planck-UCT Centre for Behaviour and Coevolution. Gabriel moved to UCT from his research fellowship at the University of Cambridge in September. 
  • Gabriel gave a talk for the “Network on the Integration of Speciation” seminar series entitled “Imprinting, speciation and host-specific adaptation in Africa’s brood-parasitic finches”.
  • PhD graduate Angela Moreras was awarded the 2023 Purcell Prize for best thesis with a zoological subject in the Department of Biological Sciences, UCT. Her thesis was entitled “Frontline strategies in the arms-race between hosts and their brood parasites: the case of the common redstart and the common cuckoo.”
  • Mairenn Attwood, Cameron Blair, Tanmay Dixit and Jess Lund all gave talks on their brood parasite research at the International Society for Behavioural Ecology conference in Melbourne, Australia. Additionally, Tanmay gave a seminar entitled “Cryptography in the bird world” at the University of Oxford.
  • Teresa Abaurrea represented the redstart-cuckoo project by giving two talks: to the Animal Behaviour Live Conference entitled “No transmission of mites from host to brood parasite: Do carotenoids protect nestlings from nest mites?” and an invited seminar to the Experimental Station for Arid Zones, National Council for Scientific Research in Spain entitled “Parent-offspring coadaptation without parental care: Common cuckoos vs Common redstarts.”
  • Several members of the brood parasite research team presented research talks at the opening workshop of the Max Planck–UCT Centre for Behaviour and Coevolution in Seewiesen, Germany, in June: Mairenn Attwood, Tanmay Dixit, Gabriel Jamie, Jess Lund, Maggie Mwale and Chima Nwaogu, as well as our long-standing collaborators Moses Chibesa from Copperbelt University; Michael Sorenson from Boston University, and Shannon Conradie, now at Wits University.
  • Cameron Blair’s MSc thesis entitled “Begging call mimicry and host manipulation by brood-parasitic honeyguides” was awarded with Distinction. The degree will be conferred at the graduation ceremony in April 2025. Cameron was supervised by Claire Spottiswoode and Jess Lund.
  • Maggie Mwale received a distinction for her MSc thesis (and for the degree overall) for her thesis entitled “Have birds’ eggs become paler as the climate warms?”, involving research conducted at our long-term study site in Zambia. Maggie was supervised by Claire Spottiswoode, Shannon Conradie and Nick Horrocks.
  • Tanmay Dixit was awarded a Certificate of Commendation by the Zoological Society of London’s Scientific Awards Committee for his PhD thesis ‘Signatures and Forgeries: optimality in a coevolutionary arms race’ (at the University of Cambridge, supervised by Claire Spottiswoode).
  • Jess Lund, Tanmay Dixit, Silky Hamama, Luke McClean and Claire Spottiswoode co-authored a paper with colleagues from the University of London entitled “Virulent brood parasites show elevated embryonic metabolic rates at specific incubation stages compared to less virulent and non-parasitic species”, published in Biology Letters.
  • Angela Moreras, Jere Tolvanen, Robert Thomson and their collaborators from various institutions in Czechia authored a paper entitled “Can nest design hinder brood parasitism success?”, published in Journal of Avian Biology.
  • The Zambia brood parasite team continued their diverse outreach and collaborative activities internationally, including presenting talks to schools in both Zambia and the UK.
  • Two members of the team, Gabriel Jamie and Maggie Mwale, were married in a joyful ceremony in Cape Town in August.

Key co-supporters
Biotechnology and Biological Sciences Research Council; The Leverhulme Trust; Natural Environment Research Council; Societas pro Fauna et Flora Fennica; Finnish Cultural Foundation; LUOVA Doctoral Programme in Wildlife Biology at the University of Helsinki.

Research team 2023
Prof. Claire Spottiswoode (FIAO, UCT / U. Cambridge)
A/Prof. Robert Thomson (FIAO, UCT)
Dr Gabriel Jamie (U. Cambridge/FIAO, UCT)
Prof. Michael Sorenson (Boston University)
Prof. L. Mahadevan (Harvard University)
Dr Nicholas Horrocks (University of Cambridge)
Dr Christopher Town (University of Cambridge)
A/Prof. Rose Thorogood (U. Helsinki, Finland)
Dr Angela Moreras (Université Laval, Canada)
Dr Jere Tolvanen (U. Oulu, Finland)
Jessie Walton (FIAO, UCT)

Students: Teresa Abaurrea (PhD, U. Helsinki); Mairenn Attwood (PhD, Cambridge); Jess Lund (PhD, Cambridge); Cameron Blair (MSc, UCT); Joel Radue (MSc, UCT); Maggie Mwale (CB MSc, UCT)

Research assistants: 
Zambia: Silky Hamama, Collins Moya, Onest Siakwasia, Sylvester Munkonko, Sanigo Mwanza, Oscar Siakwasia, Iness Liteta, Milton Simanunki, Aron Muntanga and many others.