Dr Nicholas Horrocks

Biography & Research

Dr Nicholas Horrocks

Nick Horrocks in the field during the dry season in Zambia.

I am broadly interested in how organisms cope with the challenges they face in life, whether that be from abiotic pressures such as temperature, biotic factors such as disease and pathogen pressure, or ecological factors such as intra- or interspecific competition.

I’ve been fortunate to be able to study some of these challenges by conducting fieldwork in Zambia, where I have focused on the breeding biology of greater and lesser honeyguides and their hosts – working especially with Luke McClean – and how ground-nesting birds (plovers, coursers and nightjars) cope with the extremes of temperature that they experience while incubating their eggs.

I joined the African Cuckoos team in 2013 on a two-year Marie Curie Intra-European Fellowship, having just completed my PhD at the University of Groningen, in the Netherlands. There, I studied the immune function and disease exposure of lark species in contrasting environments. I continued with a focus on ecoimmunology for my fellowship and took advantage of Claire Spottiswoode’s extensive knowledge of honeyguides in Zambia to study trade-offs between immunity and growth in these species. As virulent brood parasites, honeyguide chicks grow up potentially surrounded by the rotting carcasses of their dead nest mates. This presumably has consequences for immune investment, despite coming at a time when they must invest in growth. My research investigated how these birds manage to both stay healthy and grow at the same time.

As co-supervisor of Luke McClean’s PhD I have also been involved in some lovely studies with Luke and Claire that have investigated coevolution between honeyguides and their hosts. This has included investigating whether little bee-eaters use the dimensions of their nest tunnels as a defence against parasitism by greater honeyguides, and whether there are costs associated with the virulent egg puncturing behaviour of greater honeyguides. While chasing honeyguides during the dry season I became intrigued by the ground-nesting birds that were also breeding at that time, and was inspired by the work of Jolyon Troscianko and Jared Wilson-Aggarwal who were in the field examining camouflage efficacy and survival in plovers, coursers and nightjars. These species lay their eggs in exposed locations and rely on camouflage (either of their eggs – plovers and coursers, or themselves – nightjars) to remain undetected by predators. However, these exposed locations mean the eggs and incubating birds can be subjected to extremes of temperature, particularly during the middle of the day. Funded by a three-year Leverhulme Early Career Fellowship I have been investigating how these birds cope with the high temperatures they experience, how egg camouflage may interact with temperature, and whether birds must trade off predator avoidance behaviours with keeping their eggs protected from the sun.

While not in Zambia I have managed to combine both these research interests (interspecific interactions and temperature) by studying burying beetles (Nicrophorus) and their phoretic mites, in collaboration with Dr Syuan-Jyun Sun and Prof. Rebecca Kilner. Mites raise the body temperature of beetles, increasing their competitiveness in competitions over breeding resources. However, only small beetles, which would otherwise lose all competitive interactions, gain from the presence of mites, while larger beetles, which would win competitions anyway, lose reproductive success when breeding alongside mites. 

I have further probed the value of collaboration with Dr Jessica van der Wal and Prof. Rose Thorogood by examining how collaborative behaviour predicts career longevity and progression among behavioural ecologists.

Currently I am a Research Project Manager at the Cambridge Institute for Therapeutic Immunology & Infectious Disease. This mainly involves trying to overcome the administrative challenges of the University of Cambridge while attempting to drive forward projects to provide research facilities or collaborations to enhance research at this new institute. Projects related to COVID-19 have been a particular focus in the last months.

 

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Google Scholar Profile

News

Evolutionary Biology Crash Course

Tanmay Dixit was a member of a team organising and lecturing in the inaugural Evolutionary Biology Crash Course. This course, aimed at undergraduate or early-postgraduate students, teaches evolutionary principles to students who have had limited opportunities to be exposed to evolutionary ideas. The course is funded by the Equal Opportunities Initiative Fund of the European Society of Evolutionary Biology (ESEB). Tanmay presented lectures on behavioural ecology and evolution, focussing on kin selection, coevolution, and parasitism. Over 700 students, with the vast majority from the global South, attended the course, which was a resounding success!

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New paper on visual complexity & mimicry

Our paper “Visual complexity of egg patterns predicts egg rejection according to Weber’s Law” has just been published in the journal Proceedings of the Royal Society B. This research was led by Tanmay Dixit, and carried out together with Andrei Apostol, Kuan-Chi Chen, Tony Fulford, Chris Town and Claire Spottiswoode, in a collaboration between biologists and computer scientists. We used machine learning to compute a biologically-relevant measure of egg pattern complexity, and combined this with field experiments in Zambia to investigate how complexity evolves in an arms race between host egg signatures (by tawny-flanked prinias) and parasitic egg forgeries (by cuckoo finches).

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Fieldwork and teaching at APLORI, Nigeria

Dr Gabriel Jamie is continuing his fieldwork on the evolution of polymorphisms in cisticolas and prinias in Nigeria, where he is also a teaching fellow at the AP Leventis Ornithological Research Institute (APLORI). The image shows the 2022 APLORI MSc class during the Global Birding Big Day on 14 May. The team recorded 135 species while walking around the nature reserve surrounding the institute.

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New paper on the genetics of cuckoo finch egg mimicry

Our paper “Genetic architecture facilitates then constrains adaptation in a host-parasite coevolutionary arms race” has been published in the Proceedings of the National Academy of Sciences of the USA. In it, we address the long-standing puzzle of how exquisite mimicry of the eggs of several different host species can evolve within a single species of brood-parasitic bird. We show that in cuckoo finches in Zambia, egg mimicry of different host egg phenotypes is maternally inherited, which allows mothers to transmit host-specific adaptations to their daughters irrespective of which host species the father was raised by. This study was a team effort from colleagues at the University of Cambridge and University of Cape Town (Claire Spottiswoode, Wenfei Tong, Gabriel Jamie), at Boston University (Katherine Stryjewski, Jeff DaCosta, Evan Kuras and Michael Sorenson) and in the Choma community in Zambia (Ailsa Green, Silky Hamama, Ian Taylor and Collins Moya).

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