Funding cutting-edge ornithology
The Brenda and Tony Gibbs Award is funded by a legacy left to the BOU to specifically fund ‘research on tracking and migration studies including the use of new technologies’.

Awards up to £20,000 are aimed at funding discovery science, technological advances, high-profile conservation and research with societal impact that delivers a step change in the understanding of the movements and migrations of birds.

2022 Award | £20,000

Natal dispersal in a riverine bird: using next-generation tracking to transform our understanding of juvenile movements

Principal Investigator
Dr Stuart Sharp
Lancaster Environment Centre, Lancaster University, UK

Team members
Dr David Jacoby, Lancaster University
Prof David Winkler, Conservation Science Global

Project background
Natal dispersal, the movement of individuals from their birthplace to the site at which they first reproduce, is a fundamental ecological process with profound consequences for individual fitness and population dynamics¹. It is also a key mechanism by which organisms respond to environmental change, and so understanding the causes and consequences of dispersal is of greater importance now than ever before^1-3. However, despite a vast literature on the topic, many crucial knowledge gaps persist, not least because of the well-documented spatial and observational biases that most field studies entail^4-6. Few topics in avian biology have received more attention while remaining so difficult to resolve. Recent advances in tracking technology have revolutionised the study of avian movement and offer the best opportunities for addressing these challenges, but with most tracking studies focusing on migration⁷, the potential to produce a step change in our understanding of natal dispersal is yet to be fully realised.

Natal dispersal is widely regarded as comprising three distinct, but interrelated stages: departure from the natal site, or emigration; movement between sites, or transience; and settlement in a new site, or immigration^2,5. Individuals vary in whether and when they leave the natal area, how they move through the landscape, and when and where they finally settle. Quantifying the causes and consequences of this variation remains a critical goal of research in ecology, evolution and conservation^1-3,5, but achieving this has long been undermined by the logistical difficulties of monitoring individuals throughout each stage. Most measures of dispersal in avian studies exhibit systematic bias imposed by study site boundaries; individuals that move further from their natal area are less likely to be detected, and distinguishing between mortality and dispersal out of the site is typically impossible^4-6. Indeed, the post-fledging period is something of a ‘black box’ in avian ecology. Relatively few researchers have investigated variation in the timing of emigration, despite the potential fitness consequences; transience is often overlooked altogether, with most models of dispersal simply assuming random movement through a heterogeneous environment; and robust measures of post-juvenile survival, so valuable for population modelling, are few and far between^8-9. To overcome these issues, there is an urgent need to develop studies in which cohorts of birds can be tracked and monitored throughout the dispersal process and beyond.

Project aims
This project will use next-generation tracking technology to establish automated, comprehensive monitoring of natal dispersal in a long-term study population of the White-throated Dipper (Cinclus cinclus). Dippers are aquatic passerines which live almost exclusively along fast-flowing rivers and streams, feeding predominantly on freshwater invertebrates¹⁰. They are the ideal model species for field research on dispersal because most individuals spend their entire lives along watercourses, meaning that their territories and non-breeding habitat are linear rather than polygonal. Individuals are therefore easy to locate, catch and track as they move along predictable trajectories, and the dispersal distances of juveniles are simple and meaningful to measure (i.e. by measuring the ‘instream’ distance between the natal and breeding sites). Furthermore, the dipper is an established indicator of water quality and an Amber-listed species of conservation concern^10-11, and so investigating how environmental factors shape the ecology of dispersal in these birds has great potential to inform their conservation.

An individually marked population of c.40 breeding pairs of dippers in Yorkshire Dales National Park, UK, has been the subject of intensive study since 2013¹². Each year, all nests are found and closely monitored, and a series of key life-history, behavioural and environmental data are collected. For this project, a network of Cellular Tracking Technologies (CTT) radio-tracking transmitters and receivers will be deployed across the study site to establish automated, real-time tracking of natal dispersal. CTT sensor stations will be sited on each river, together with a series of ‘nodes’ which relay signals to the sensor stations; signal data are uploaded to the cloud automatically. Juveniles will be fitted with tags which transmit a unique signal multiple times per minute over several kilometres. This network will therefore produce unprecedented fine-scale movement data which can be used to measure accurately the timing and distance of natal dispersal, the pattern of movements undertaken along the way, and the timing and location of death. By combining this information with the long-term data collected both in the year of birth and the year of first reproduction, this research will provide novel insights into each of the three stages of dispersal. The specific objectives are to:

1. Quantify the effect of phenotypic traits (e.g. sex, body size), early life conditions (e.g. natal brood size, parental investment) and environmental factors (e.g. food availability, river flow) on the timing and distance of natal dispersal;
2. Characterise individual behaviour, movement and survival during transience;
3. Measure the fitness consequences of the timing and distance of dispersal, and behaviour during transience, in the first year of reproduction.

This study will be among the first to produce direct measures of avian dispersal at the population scale and will address key knowledge gaps in the dispersal literature, with important implications for behavioural and population ecology. The work will also inform research that aims to predict and mitigate how birds respond to environmental change. Finally, this project aims to support the conservation of the UK’s river birds, most of which are in decline¹¹, by raising awareness of key issues among the different stakeholders of the national park and in the wider community; it therefore offers an excellent opportunity to promote river bird conservation and the work of the BOU.

References

1. Clobert, J, Baguette, M., Benton, T.G. & Bullock, J.M. 2012. Dispersal Ecology and Evolution. Oxford University Press.
2. Bonte, D. et al. 2012. Costs of dispersal. Biological Reviews 87: 290-312.
3. Driscoll, D.A. et al. 2014. The trajectory of dispersal research in conservation biology. PLoS ONE 9: e95053.
4. Koenig, W.D., Van Vuren, D. & Hooge P.N. 1996. Detectability, philopatry, and the distribution of dispersal distances in vertebrates. Trends in Ecology and Evolution 11: 514-517.
5. Bowler, D.E. & Benton, T.G. 2005. Causes and consequences of animal dispersal strategies: relating individual behaviour to spatial dynamics. Biological Reviews 80: 205-225.
6. Sharp, S.P., Baker, M.B., Hadfield, J.D., Simeoni, M. & Hatchwell, B.J. 2008. Natal dispersal and recruitment in a cooperatively breeding bird. Oikos 117: 1371-1379.
7. McKinnon, E.A. & Love, O.P. 2018. Ten years tracking the migrations of small landbirds: Lessons learned in the golden age of bio-logging. Auk 135: 834-856.
8. Cox, W.A., Thompson III, F.R., Cox, A.S. & Faaborg, J. 2014. Post-fledging survival in passerine birds and the value of post-fledging studies to conservation. Journal of Wildlife Management 78: 183-193.
9. Naef-Daenzer, B. & Grüebler, M.U. 2016. Post-fledging survival of altricial birds: ecological determinants and adaptation. Journal of Field Ornithology 87: 227-250.
10. Tyler, S.J. & Ormerod, S.J. 1994. The Dippers. T & AD Poyser.
11. Stanbury, A. et al. 2021. The status of our bird populations: the fifth Birds of Conservation Concern in the United Kingdom, Channel Islands and Isle of Man and second IUCN Red List assessment of extinction risk for Great Britain. British Birds 114: 723-747.
12. Crowther, W., Magoolagan, L., Mawby, P.J., Whitehead, F.A., Wright, P.M. & Sharp, S.P. 2018. Winter territoriality and its implications for the breeding ecology of White-throated Dippers Cinclus cinclus. Bird Study 65: 471-477.

Images
White-throated Dipper Cinclus cinclus Ron Knight CC BY 2.0 Wikimedia Commons