Award details

Predator Vision and Avian Egg Camouflage

Reference	BB/J018309/1
Principal Investigator / Supervisor	Professor Martin Stevens
Co-Investigators / Co-Supervisors
Institution	University of Cambridge
Department	Zoology
Funding type	Research
Value (£)	418,613
Status	Completed
Type	Research Grant
Start date	01/08/2012
End date	14/01/2013
Duration	5 months

Abstract

Avoiding predation is a crucial aspect of many animals' fitness. A widespread defence is camouflage, which is a textbook example of natural selection. Animal camouflage has also influenced human applications and culture, including the military, art and fashion. In nature, many types of camouflage may exist. These include background matching, where the animal matches the appearance of its environment, disruptive coloration, where the body outline is broken up by contrasting markings, and masquerade, where animals resemble an unimportant object such as a leaf or stone. In the last decade a resurgent research agenda has investigated the types of camouflage that may exist and how they work in terms of predator vision. Studies of camouflage have been undertaken by evolutionary, sensory, and molecular biologists, psychologists, and computer scientists. However, we know little about camouflage in real animals because theoretical work has almost entirely been undertaken in artificial systems. Here, we use camouflage in bird eggs as a model system to test key questions about camouflage. Avian egg camouflage is a perfect system because the backgrounds on which species nest is well-known, and substantial information about breeding biology and predators exist. We will conduct research in South Africa and Zambia, using several groups of birds (mainly plovers and nightjars). We will locate nests and use computer models of animal vision and image analysis to quantify the level and type of camouflage present. In addition, we will obtain survival analysis of nests over time and record predation events to determine the main predator groups. Using these data, we will answer: 1) how the level and type of camouflage affects survival, 2) how background structure influences the type of camouflage that evolves, and 3) how species that nest on multiple backgrounds optimise concealment. Our study addresses fundamental issues about how camouflage influences survival in natural environments.

Summary

Few things are more important to an animal than avoiding predation. As soon as Darwin and Wallace presented their theory of evolution by natural selection, around 150 years ago, the numerous ways of avoiding predation provided crucial examples for illustrating and defending natural selection and adaptation. Animal coloration has also influenced many areas of human applications and culture. For example, camouflage is of great importance in military applications and has influenced peaceful areas of culture such as art and fashion. Camouflage is one of the most important anti-predator adaptations in nature and crucial to the survival of individuals in countless species. It is a textbook example of natural selection. Given the importance of camouflage, it is unsurprising that many different types exist. These include background matching, where the animal matches the general appearance of its environment, and disruptive coloration, where the outline of the animal's body is broken up by strongly contrasting markings. In addition, some animals may use masquerade, where they resemble an apparently unimportant object in the environment such as a leaf or stone. Within the last decade substantial research has investigated the different types of camouflage that may exist and how they may work in terms of predator vision. Studies of camouflage have been undertaken by evolutionary, sensory, molecular, and behavioural biologists, experimental psychologists, artists and computer scientists. Camouflage research is consequently a vibrant and interdisciplinary area and a model system for investigating animal behaviour, vision, and evolutionary biology. However, numerous gaps in our knowledge remain. Remarkably, given how important camouflage is, we still know little about it in real animals. While recent theoretical breakthroughs have been numerous, work has almost entirely been undertaken in artificial systems. Consequently, we know little of how such findings relate to the natural world. In short, camouflage theory from artificial systems greatly outstrips our understanding in real species and habitats. However, we can now use this theory to make a range of predictions about camouflage and its evolution in the wild. In this project, we use camouflage in birds eggs as a model system to test several key questions about concealment, its value and evolution. Avian egg camouflage makes a wonderful system because the backgrounds on which many species nest is well known, substantial information about breeding biology exists, predators are often well documented, and bird eggs in many species have impressive camouflage. We will conduct research in South Africa and Zambia over two field seasons, using several groups of birds (mainly plovers and nightjars). We will locate nests of various species and undertake analyses of the colour and pattern of the eggs against the background on which they were laid. Using mathematical models of animal vision and techniques from computer science, we will analyse how camouflaged the different egg types are against the different available backgrounds, and determine the camouflage type that is present. In addition, we will check nests at regular intervals over the incubation period and determine which nests are eaten by predators and how long the different eggs survived. We will record predation events to determine the main predator groups for each species so that we can model egg appearance in terms of predator vision. Using these data, we will answer several key questions: 1) how does the level and type of camouflage affect the survival of an individual's eggs, 2) does the background structure influence the type of camouflage that evolves, and 3) how do species that nest on multiple background types optimise their level of concealment over evolution? Our study will reveal fundamental answers about how the type and level of camouflage influences survival in complex natural environments.

Impact Summary

(1) Public Outreach, Education and Learning Animal coloration, including camouflage can readily attract significant media attention and captivate public interest. It is highly visual, and the concepts of predation and animal coloration are widely appealing and understandable. Such concepts generally receive coverage in popular science books, newspapers, television and radio, and exhibitions. Animal coloration and camouflage has inspired areas of art and fashion, including exhibitions at various galleries and museums. The PI has appeared on and helped with radio programmes and TV series, and his research has been covered on various occasions in the media, including National Geographic, New Scientist, the BBC, and the New York Times. He has dealt with journalists and press offices regularly including issuing press releases and interviews. As well as being ideal to appeal to both to the general public and media, the project also represents a key example of natural selection that can be used to illustrate a range of key concepts regarding evolution and natural history to children and young adults. It is a key aim of ours to communicate our work and its principles to these audiences. To this end, we will enrol as Science and Engineering Ambassadors to present our work at schools/colleges, and present displays and interactive encounters at the Cambridge Science Festival and the Royal Society Summer Science Exhibition. We will also set up a website containing high-quality images and videos and an educational game illustrating key principles of camouflage, predation, and evolution using visual aids from our fieldwork. We will also acquire a database of images and videos for use by the media, teachers, and artists. Finally, the digital imaging methods in our project would also allow the production of photographs showing how non-human animals (e.g. predators), 'see' the world around them. Our images and videos will also be valuable to go alongside press releases. (2) Economic Camouflage has long had significant application in the military, plus in human recreation and commerce (e.g. hunting and wildlife watching). The PI has organised a conference on animal vision and camouflage, which was attended by members of the military, and is cosupervising a CASE PhD project partly funded by the Ministry of Defence. In addition to designing camouflage, there is also a need for camouflage breaking. To do this, requires an understanding of how camouflage works in natural environments, and often utilises imaging approaches. There is also an increasing effort to disguise unattractive but functional human made objects, such as mobile phone transmission masts and satellite dishes, and successful ways of doing so would yield financial rewards. Once we have acquired and analysed sufficient data to have obtained preliminary findings, we will coordinate with relevant departments and organisations about the application and exploitation of our work. The key insights our project will give is information about what types of camouflage work best against different background and habitat types, and how camouflage can be optimised in complex real world systems (natural or anthropogenic).

Committee	Research Committee A (Animal disease, health and welfare)
Research Topics	Animal Welfare
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

Associated awards:

BB/J018309/2 Predator Vision and Avian Egg Camouflage

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