Ecological and behavioural constraints on range expansion in migratory birds

Lead Research Organisation: University of East Anglia
Department Name: Biological Sciences

Abstract

For many species, changing climatic conditions are altering the suitability of the landscapes that they currently inhabit. The future success of such species may depend on their ability to shift their distribution to areas where conditions are suitable, which will require individuals to disperse to new sites. Migratory birds might be expected to be most capable of such dispersal, given the vast distances over which they travel. However, individual birds are typically highly site-faithful to their breeding and winter sites, and so dispersal events can be rare. The success of dispersal events will also depend on the quality of the habitat available to dispersing individuals. Individual dispersal behaviour and habitat availability can therefore help or hinder a species' capacity to shift distribution in response to climate change. Exploring the relative importance of these ecological and behavioural constraints for migratory birds requires a system in which 1. habitat quality has been identified, 2. changes in range size and distribution have been documented and 3. individual dispersal decisions can be tracked. Icelandic black-tailed godwits have been increasing in number and range in recent decades and expanding into poorer quality habitats in summer and winter. Our long-term marking and tracking of these godwits has shown that birds in new breeding sites tend to also use new winter sites, and that they tend to be larger than birds in traditional breeding sites. Larger birds may be more common on new sites either because they can cope better with conditions in these sites or because these are less successful individuals that are more likely to disperse to try and find a mate. This study therefore provides a unique opportunity to explore the consequences of range expansion in a migratory species, by measuring the quality of new sites and the probability of birds in new sites breeding successfully. This study will greatly improve our understanding of the potential for migratory species to expand their ranges, and of the demographic and evolutionary consequences of such range shifts.

Publications

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Description For many species, changing climatic conditions are altering the suitability of the landscapes that they currently inhabit. The future success of such species may depend on their ability to shift their distribution to areas where conditions are suitable, which will require individuals to disperse to new sites. Migratory birds might be expected to be most capable of such dispersal, given the vast distances over which they travel. However, individual birds are typically highly site-faithful to their breeding and winter sites, and so dispersal events can be rare. The success of dispersal events will also depend on the quality of the habitat available to dispersing individuals. Individual dispersal behaviour and habitat availability can therefore help or hinder a species' capacity to shift distribution in response to climate change.



To explore the importance of these ecological and behavioural constraints for migratory birds, we have developed a study system in which 1. habitat quality has been identified, 2. changes in range size and distribution have been documented and 3. individual dispersal decisions can be tracked. Icelandic black-tailed godwits have been increasing in number and range in recent decades. Our long-term marking and tracking of these godwits throughout their migratory range has shown that birds in new breeding sites tend to also use new winter sites, and that they tend to be larger than birds in traditional breeding sites. Our research has shown that the rate of range expansion in this species can be strongly influenced by habitat quality and seasonal interactions, as breeding success, survival and energetic benefits in winter are all lower in more recently occupied sites. However, in addition to this, agricultural expansion in Iceland appears to be altering the quality of the breeding habitat, particularly in more recently occupied areas. Land use change in Iceland may therefore be facilitating the rate of range expansion, particularly for individuals occupying more recently colonised sites, but strong seasonal interactions mean that conditions in the non-breeding season can potentially constrain the benefits of these changes.
Exploitation Route Our findings can directly inform the development of conservation strategies to facilitate range expansion in species of conservation concern
Sectors Environment

 
Description Development of International Species Action Plans
Geographic Reach Asia 
Policy Influence Type Membership of a guidance committee
 
Description Collaboration between universities and citizen scientists 
Organisation University of Iceland
Country Iceland 
Sector Academic/University 
PI Contribution This research involves collaboration between the Universities of East Anglia, Cambridge and Iceland, with substantial collaboration and contributions from volunteer 'citizen scientists' from across Europe who collect data for the research.
Start Year 2000
 
Description Blog series - wadertales 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact We work closely with a professional science communicator to produce blogs describing our research
Year(s) Of Engagement Activity 2015,2016,2017,2018
URL https://wadertales.wordpress.com/
 
Description Public communication 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Regular communication with volunteers who contribute data to the study, and frequent presentations of research findings to the public

We regularly give public presentations (2-3 per year) on our research in order to foster public understanding of science and to encourage direct involvement in the study by volunteer citizen scientists
Year(s) Of Engagement Activity Pre-2006,2006,2007,2008,