Parental responses to variation in egg odour during incubation

Avian parents directly affect the rate and success of embryonic development by determining the onset of incubation, temperature during incubation, nest microclimate and the rate of egg turning. However, unlike in viviparous animals, where developing embryos can potentially communicate their developmental requirements to their parent (e.g. via hormones), resulting in beneficial changes to their developmental environment, this is not so easy for egg-bound embryos. Indeed, until the embryonic vocalisation system develops towards the end of the incubation period, there would appear little opportunity for embryos to convey their developmental requirements to incubating parents and therefore little opportunity for embryos to influence their microenvironment (e.g. to make it warmer or cooler) by manipulating parental behaviour.

Based on pilot data showing that (a) eggs release odour throughout incubation that is sufficient to provide information on their viability and thermal requirements, and (b) that birds can detect these odours, this proposal aims to test the novel hypothesis that embryo requirements during incubation can be determined via olfactory cues produced by eggs, and that parents not only detect these cues, but alter their behaviour accordingly. Specifically, using artificial eggs that can release synthetic odours that match those produced by real eggs, I will test whether (i) parents pay less attention to eggs that show no olfactory signs of development (i.e., 'smell' infertile) compared to 'fertile' controls (Experiment 1), and (ii) parents respond to olfactory cues consistent with hypothermic eggs with behaviours intended to increase egg temperature (Experiment 2).

This work will not only be an extremely novel contribution to the work on avian olfaction, which is still very much in its infancy, but will be the first step in understanding embryo-parent interactions during early incubation. The results of the proposed experiments will lead directly to further NERC funding applications to explore the fitness consequences of these interactions for embryos and their parent(s) and how these processes operate in natural nests and across species. In the longer term, it may also lead to the development of odour-based systems to monitor egg development both commercially and during captive breeding programmes.

The question of whether birds have a functional sense of smell has recently started to receive concerted research interest, and the notion that olfactory behaviour plays little or no role in their daily lives has largely been overturned. However, we are still far from understanding the functions of olfaction in most avian species. This curiosity-driven study is focussed on understanding whether the odorous compounds released by birds' eggs during incubation play any role in the incubation process, perhaps by allowing incubating parents to detect the developmental requirements of the embryo long before they can communicate directly (e.g. using in ovo vocalisations) and so modify their incubation behaviour accordingly. This is not only a question of fundamental importance for behavioural ecologists, but the approaches used and techniques developed will have wider applications in studying this and related phenomena; for example, incubation specialists would be extremely interested in non-invasive ways of assessing egg viability and development. We intend to focus our specific-user activity on scientific advancement, skills and knowledge. Specifically, we will engage in the following activities:

(i) Disseminate information to incubation specialists. We will provide information for those involved in the artificial incubation of avian eggs, both commercially (e.g. commercial poultry breeders, of which there are many in and around Lincolnshire), and as part of captive breeding programmes (e.g. those undertaken in zoos), on the possibility of using egg-odours for the assessment of embryo development and viability. This will have the aim of looking for possible avenues for commercial development.

(ii) Training for the PDRA. The project provide excellent training for the PDRA in a range of different experimental and analytical techniques and methodologies, experimental design and analysis, and paper writing. They will also be encouraged to apply for an independent fellowship at the end of the project. Moreover, as a standard activity within the University, we will ensure that the PDRA selected is provided with the opportunity to develop their awareness of, and skills in, knowledge transfer so that we can contribute to training the 'next generation of scientists'.

(iii) Public understanding of science. The applicant is committed to the public understanding of science, and the Department of Biological Sciences at the University of Lincoln has been very successful in publicizing its work in the national and international media. Our work has been publicised in the national and international media and we will continue to ensure that the work we do is disseminated widely. We will also disseminate the research on personal and university web pages, and where possible will engage in public communication such as television and radio programmes and by contributing to popular science magazines.