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

Dr Gabriel Jamie awarded a Leverhulme Early Career Fellowship

Dr Gabriel Jamie has been awarded a Leverhulme Early Career Fellowship based at University of Cambridge. For the fellowship Gabriel will build on his previous work on brood parasitism and the evolution of polymorphisms to understand the incredible diversity of egg...

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New paper published on Weber’s Law and mimicry

Our paper ‘Why and how to apply Weber’s Law to coevolution and mimicry’ has been published in the journal Evolution. This perspectives paper, written by Tanmay Dixit, Eleanor Caves, Claire Spottiswoode, and Nicholas Horrocks, argues that Weber’s Law of proportional processing can lead to otherwise counterintuitive predictions about the evolutionary trajectories of mimicry systems.  Weber’s Law states that when the magnitude of a stimulus is large, it is more difficult to discriminate a change or difference from that stimulus. In other words, relative differences are more salient than absolute differences. We show that Weber’s Law could have implications for mimicry: when stimulus magnitudes are high, it should be more difficult to discriminate a model from a mimic. This leads to testable predictions about evolutionary trajectories of models and mimics. We also present a framework for testing Weber’s Law and its implications for coevolution. 

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New paper on evolution of egg signatures

Our paper “Hosts elevate either within-clutch consistency or between-clutch distinctiveness of egg phenotypes in defence against brood parasites” has just been published in the journal Proceedings of the Royal Society of London B. In this study, led by Eleanor Caves, we asked how host eggs evolve adaptations that allow them better to discriminate their own eggs from parasitic eggs. Theoretically, hosts can generate their own individually-distinctive egg ‘signatures’ by laying eggs that appear similar to one another (consistency) but look very different from other individuals’ eggs (distinctiveness). In this new study, we show that host species of two African brood parasites deploy either consistency or distinctiveness, but not both, as defences, and achieve distinctiveness by combining egg colours and patterns in unpredictable combinations.

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Mairenn Attwood awarded Cambridge teaching prize

Congratulations to Mairenn Attwood for being awarded the Janet Moore Prize for teaching in the Department of Zoology at the University of Cambridge, for her outstanding tutorial supervision of final-year undergraduate students, who praised her breadth and depth of knowledge, enthusiasm, and friendliness.  Mairenn follows in the footsteps of Tanmay Dixit who was awarded the Janet Moore Prize in 2020. Well done both for inspiring the next generation of behavioural ecologists!

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