Nest Camouflage in Nightjars & Other Birds

Introduction

Fiery-necked Nightjar

A Fiery-necked Nightjar brooding two chicks among leaf litter in Zambia.

Nesting nightjars (and other ground-nesting birds such as plovers and coursers) are a particularly neat system for studying the evolution of camouflage in the wild: they don’t build any kind of nest structure but just lay their eggs directly on the natural background, which means they depend completely on the appearance of their eggs or their own bodies for concealment. It’s also important that nests by definition are in a fixed location – so you know the bird has chosen that spot rather than happening to have landed there after being disturbed. At our study site in Zambia we have several species of nightjar, plover and courser breed out in the open in the baking heat of the late dry season. They need to make sure that their eggs (and themselves) are protected not only from predators but also dangerously high temperatures out in the sun at midday.

Jolyon and Jared

Jolyon Troscianko and Jared Wilson-Aggarwal in the field in Zambia, photographing an incubating Fiery-necked Nightjar using a UV-sensitive camera.

We’ve been studying nightjars, coursers and plovers in the field in Zambia since 2011. These birds are currently the focus of Dr Nick Horrocks‘s work on thermal ecology. They were previously the focus of a BBSRC-funded research project in collaboration with the Sensory Ecology Group Exeter University, co-led by Exeter’s Dr Martin Stevens and carried out by Dr Jolyon Troscianko and Jared Wilson-Aggarwal. Please read more about our work on the ProjectNightjar website, help us with our research by posing as a predator in an online computer game and exerting some natural selection on ever-evolving populations of virtual eggs, have a look at the photo galleries below of real nightjars and coursers in the field, and join nearly half a million others in watching this very short video that our funders, the BBSRC, made using our film footage from Zambia:

Publications

  • Stevens, M., Troscianko, J., Wilson-Aggarwal, J.K. & Spottiswoode, C.N. 2017 Improvement of individual camouflage through background choice in ground-nesting birds. Nature Ecology & Evolution 1: 1325-1333. Read on journal website [Open Access]
  • Troscianko, J. Wilson-Aggarwal, J., Griffiths, D., Spottiswoode, C.N. & Stevens, M. (2017) Relative advantages of dichromatic and trichromatic color vision in camouflage breaking. Behavioral Ecology 28: 556-564. Read on journal website [Open Access]
  • Troscianko, J., Wilson-Aggarwal, J., Spottiswoode, C.N. & Stevens, M. (2016) Nest covering in plovers: how modifying the visual environment influences egg camouflage. Ecology and Evolution doi: 10.1002/ece3.2494 Read on journal website [Open Access]
  • Wilson-Aggarwal, J., Troscianko, J., Stevens, M. & Spottiswoode, C.N. (2016) Escape distance in ground-nesting birds differs with level of individual camouflage. American Naturalist 188: 231–239. Read on journal website [Open Access]
  • Troscianko, J., Wilson-Aggarwal, J., Stevens, M. & Spottiswoode, C.N. (2016) Camouflage directly predicts the survival probability of ground-nesting birds. Scientific Reports 6: 19966. Read on journal website [Open Access]

Nightjar Photo Gallery

Coursers Photo Gallery

News

New paper on imperfect egg mimicry

Our paper “Combined measures of mimetic fidelity explain imperfect mimicry in a brood parasite-host system” has just been published in the journal Biology Letters. This study was led by Tanmay Dixit, and carried out together with Gary Choi, Salem al-Mosleh, Jess Lund, Jolyon Troscianko, Collins Moya, L Mahadevan, and Claire Spottiswoode, as part of a collaboration between our group and Prof. Mahadevan and his lab at Harvard University. Together we combined mathematical tools and field experiments in Zambia to quantify a key difference – “squiggle” markings – between the eggs of hosts (tawny-flanked prinias) and parasites (cuckoo finches). We showed that suboptimal behaviour on the part of prinias allows cuckoo finches to get by with an imperfect copy of prinia eggs.

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New paper on host aggression and hawk mimicry

Our paper “Aggressive hosts are undeterred by a cuckoo’s hawk mimicry, but probably make good foster parents” has just been published in the journal Proceedings of the Royal Society B. In the paper, we investigate the costs and benefits to the African cuckoo of specializing on a highly aggressive host species, the fork-tailed drongo.

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African Cuckoos Team at the Pan-African Ornithological Congress

The African Cuckoos Team had a fantastic time at the Pan-African Ornithological Congress (PAOC15), this year held in Vic Falls, Zimbabwe. Dr Chima Nwaogu gave a plenary talk on “Differing Priorities in the Timing of Annual Life History Events”, while Professor Claire Spottiswoode and Silky Hamama presented during a roundtable session on communities in conservation and research. Silky also presented a poster, with Claire, Jess Lund, Mairenn Attwood and Cameron Blair each giving research talks as well. 

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